Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1 | .TH DNSMASQ 8 |
| 2 | .SH NAME |
| 3 | dnsmasq \- A lightweight DHCP and caching DNS server. |
| 4 | .SH SYNOPSIS |
| 5 | .B dnsmasq |
| 6 | .I [OPTION]... |
| 7 | .SH "DESCRIPTION" |
| 8 | .BR dnsmasq |
Simon Kelley | 34d0a36 | 2013-01-02 11:40:56 +0000 | [diff] [blame] | 9 | is a lightweight DNS, TFTP, PXE, router advertisement and DHCP server. It is intended to provide |
Simon Kelley | 5aabfc7 | 2007-08-29 11:24:47 +0100 | [diff] [blame] | 10 | coupled DNS and DHCP service to a LAN. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 11 | .PP |
| 12 | Dnsmasq accepts DNS queries and either answers them from a small, local, |
| 13 | cache or forwards them to a real, recursive, DNS server. It loads the |
| 14 | contents of /etc/hosts so that local hostnames |
| 15 | which do not appear in the global DNS can be resolved and also answers |
Simon Kelley | ee41586 | 2014-02-11 11:07:22 +0000 | [diff] [blame] | 16 | DNS queries for DHCP configured hosts. It can also act as the |
| 17 | authoritative DNS server for one or more domains, allowing local names |
| 18 | to appear in the global DNS. It can be configured to do DNSSEC |
| 19 | validation. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 20 | .PP |
Simon Kelley | 73a08a2 | 2009-02-05 20:28:08 +0000 | [diff] [blame] | 21 | The dnsmasq DHCP server supports static address assignments and multiple |
| 22 | networks. It automatically |
Simon Kelley | 3be3454 | 2004-09-11 19:12:13 +0100 | [diff] [blame] | 23 | sends a sensible default set of DHCP options, and can be configured to |
Simon Kelley | f2621c7 | 2007-04-29 19:47:21 +0100 | [diff] [blame] | 24 | send any desired set of DHCP options, including vendor-encapsulated |
Simon Kelley | 1b7ecd1 | 2007-02-05 14:57:57 +0000 | [diff] [blame] | 25 | options. It includes a secure, read-only, |
Simon Kelley | 34d0a36 | 2013-01-02 11:40:56 +0000 | [diff] [blame] | 26 | TFTP server to allow net/PXE boot of DHCP hosts and also supports BOOTP. The PXE support is full featured, and includes a proxy mode which supplies PXE information to clients whilst DHCP address allocation is done by another server. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 27 | .PP |
Simon Kelley | 81925ab | 2013-04-10 11:43:58 +0100 | [diff] [blame] | 28 | The dnsmasq DHCPv6 server provides the same set of features as the |
| 29 | DHCPv4 server, and in addition, it includes router advertisements and |
| 30 | a neat feature which allows nameing for clients which use DHCPv4 and |
Simon Kelley | 834f36f | 2013-04-17 13:52:49 +0100 | [diff] [blame] | 31 | stateless autoconfiguration only for IPv6 configuration. There is support for doing address allocation (both DHCPv6 and RA) from subnets which are dynamically delegated via DHCPv6 prefix delegation. |
Simon Kelley | 34d0a36 | 2013-01-02 11:40:56 +0000 | [diff] [blame] | 32 | .PP |
| 33 | Dnsmasq is coded with small embedded systems in mind. It aims for the smallest possible memory footprint compatible with the supported functions, and allows uneeded functions to be omitted from the compiled binary. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 34 | .SH OPTIONS |
| 35 | Note that in general missing parameters are allowed and switch off |
Simon Kelley | 832af0b | 2007-01-21 20:01:28 +0000 | [diff] [blame] | 36 | functions, for instance "--pid-file" disables writing a PID file. On |
Simon Kelley | 33820b7 | 2004-04-03 21:10:00 +0100 | [diff] [blame] | 37 | BSD, unless the GNU getopt library is linked, the long form of the |
| 38 | options does not work on the command line; it is still recognised in |
| 39 | the configuration file. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 40 | .TP |
Simon Kelley | 7622fc0 | 2009-06-04 20:32:05 +0100 | [diff] [blame] | 41 | .B --test |
| 42 | Read and syntax check configuration file(s). Exit with code 0 if all |
| 43 | is OK, or a non-zero code otherwise. Do not start up dnsmasq. |
| 44 | .TP |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 45 | .B \-h, --no-hosts |
| 46 | Don't read the hostnames in /etc/hosts. |
| 47 | .TP |
| 48 | .B \-H, --addn-hosts=<file> |
| 49 | Additional hosts file. Read the specified file as well as /etc/hosts. If -h is given, read |
Simon Kelley | fd9fa48 | 2004-10-21 20:24:00 +0100 | [diff] [blame] | 50 | only the specified file. This option may be repeated for more than one |
Simon Kelley | 7622fc0 | 2009-06-04 20:32:05 +0100 | [diff] [blame] | 51 | additional hosts file. If a directory is given, then read all the files contained in that directory. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 52 | .TP |
Simon Kelley | 3d04f46 | 2015-01-31 21:59:13 +0000 | [diff] [blame] | 53 | .B --hostsdir=<path> |
| 54 | Read all the hosts files contained in the directory. New or changed files |
| 55 | are read automatically. See --dhcp-hostsdir for details. |
| 56 | .TP |
Simon Kelley | 832af0b | 2007-01-21 20:01:28 +0000 | [diff] [blame] | 57 | .B \-E, --expand-hosts |
| 58 | Add the domain to simple names (without a period) in /etc/hosts |
Simon Kelley | 1f15b81 | 2009-10-13 17:49:32 +0100 | [diff] [blame] | 59 | in the same way as for DHCP-derived names. Note that this does not |
| 60 | apply to domain names in cnames, PTR records, TXT records etc. |
Simon Kelley | 832af0b | 2007-01-21 20:01:28 +0000 | [diff] [blame] | 61 | .TP |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 62 | .B \-T, --local-ttl=<time> |
| 63 | When replying with information from /etc/hosts or the DHCP leases |
| 64 | file dnsmasq by default sets the time-to-live field to zero, meaning |
Simon Kelley | c72daea | 2012-01-05 21:33:27 +0000 | [diff] [blame] | 65 | that the requester should not itself cache the information. This is |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 66 | the correct thing to do in almost all situations. This option allows a |
| 67 | time-to-live (in seconds) to be given for these replies. This will |
| 68 | reduce the load on the server at the expense of clients using stale |
| 69 | data under some circumstances. |
| 70 | .TP |
Simon Kelley | 824af85 | 2008-02-12 20:43:05 +0000 | [diff] [blame] | 71 | .B --neg-ttl=<time> |
| 72 | Negative replies from upstream servers normally contain time-to-live |
| 73 | information in SOA records which dnsmasq uses for caching. If the |
| 74 | replies from upstream servers omit this information, dnsmasq does not |
| 75 | cache the reply. This option gives a default value for time-to-live |
| 76 | (in seconds) which dnsmasq uses to cache negative replies even in |
| 77 | the absence of an SOA record. |
| 78 | .TP |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 79 | .B --max-ttl=<time> |
| 80 | Set a maximum TTL value that will be handed out to clients. The specified |
| 81 | maximum TTL will be given to clients instead of the true TTL value if it is |
| 82 | lower. The true TTL value is however kept in the cache to avoid flooding |
| 83 | the upstream DNS servers. |
| 84 | .TP |
Simon Kelley | 1d86041 | 2012-09-20 20:48:04 +0100 | [diff] [blame] | 85 | .B --max-cache-ttl=<time> |
| 86 | Set a maximum TTL value for entries in the cache. |
| 87 | .TP |
RinSatsuki | 28de387 | 2015-01-10 15:22:21 +0000 | [diff] [blame] | 88 | .B --min-cache-ttl=<time> |
| 89 | Extend short TTL values to the time given when caching them. Note that |
| 90 | artificially extending TTL values is in general a bad idea, do not do it |
| 91 | unless you have a good reason, and understand what you are doing. |
| 92 | Dnsmasq limits the value of this option to one hour, unless recompiled. |
| 93 | .TP |
Simon Kelley | 333b2ce | 2013-01-07 21:46:03 +0000 | [diff] [blame] | 94 | .B --auth-ttl=<time> |
| 95 | Set the TTL value returned in answers from the authoritative server. |
| 96 | .TP |
Simon Kelley | 3be3454 | 2004-09-11 19:12:13 +0100 | [diff] [blame] | 97 | .B \-k, --keep-in-foreground |
| 98 | Do not go into the background at startup but otherwise run as |
Simon Kelley | 3d8df26 | 2005-08-29 12:19:27 +0100 | [diff] [blame] | 99 | normal. This is intended for use when dnsmasq is run under daemontools |
| 100 | or launchd. |
Simon Kelley | 3be3454 | 2004-09-11 19:12:13 +0100 | [diff] [blame] | 101 | .TP |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 102 | .B \-d, --no-daemon |
| 103 | Debug mode: don't fork to the background, don't write a pid file, |
| 104 | don't change user id, generate a complete cache dump on receipt on |
Simon Kelley | 3be3454 | 2004-09-11 19:12:13 +0100 | [diff] [blame] | 105 | SIGUSR1, log to stderr as well as syslog, don't fork new processes |
Simon Kelley | 83b2198 | 2012-11-12 21:07:44 +0000 | [diff] [blame] | 106 | to handle TCP queries. Note that this option is for use in debugging |
| 107 | only, to stop dnsmasq daemonising in production, use |
| 108 | .B -k. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 109 | .TP |
| 110 | .B \-q, --log-queries |
Simon Kelley | 25cf5e3 | 2015-01-09 15:53:03 +0000 | [diff] [blame] | 111 | Log the results of DNS queries handled by dnsmasq. Enable a full cache dump on receipt of SIGUSR1. If the argument "extra" is supplied, ie |
| 112 | .B --log-queries=extra |
| 113 | then the log has extra information at the start of each line. |
| 114 | This consists of a serial number which ties together the log lines associated with an individual query, and the IP address of the requestor. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 115 | .TP |
Simon Kelley | 849a835 | 2006-06-09 21:02:31 +0100 | [diff] [blame] | 116 | .B \-8, --log-facility=<facility> |
| 117 | Set the facility to which dnsmasq will send syslog entries, this |
Simon Kelley | f2621c7 | 2007-04-29 19:47:21 +0100 | [diff] [blame] | 118 | defaults to DAEMON, and to LOCAL0 when debug mode is in operation. If |
Simon Kelley | 9e03894 | 2008-05-30 20:06:34 +0100 | [diff] [blame] | 119 | the facility given contains at least one '/' character, it is taken to |
Simon Kelley | f2621c7 | 2007-04-29 19:47:21 +0100 | [diff] [blame] | 120 | be a filename, and dnsmasq logs to the given file, instead of |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 121 | syslog. If the facility is '-' then dnsmasq logs to stderr. |
| 122 | (Errors whilst reading configuration will still go to syslog, |
Simon Kelley | f2621c7 | 2007-04-29 19:47:21 +0100 | [diff] [blame] | 123 | but all output from a successful startup, and all output whilst |
Simon Kelley | 5aabfc7 | 2007-08-29 11:24:47 +0100 | [diff] [blame] | 124 | running, will go exclusively to the file.) When logging to a file, |
| 125 | dnsmasq will close and reopen the file when it receives SIGUSR2. This |
| 126 | allows the log file to be rotated without stopping dnsmasq. |
Simon Kelley | f2621c7 | 2007-04-29 19:47:21 +0100 | [diff] [blame] | 127 | .TP |
| 128 | .B --log-async[=<lines>] |
| 129 | Enable asynchronous logging and optionally set the limit on the |
| 130 | number of lines |
| 131 | which will be queued by dnsmasq when writing to the syslog is slow. |
| 132 | Dnsmasq can log asynchronously: this |
| 133 | allows it to continue functioning without being blocked by syslog, and |
| 134 | allows syslog to use dnsmasq for DNS queries without risking deadlock. |
| 135 | If the queue of log-lines becomes full, dnsmasq will log the |
| 136 | overflow, and the number of messages lost. The default queue length is |
| 137 | 5, a sane value would be 5-25, and a maximum limit of 100 is imposed. |
Simon Kelley | 849a835 | 2006-06-09 21:02:31 +0100 | [diff] [blame] | 138 | .TP |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 139 | .B \-x, --pid-file=<path> |
| 140 | Specify an alternate path for dnsmasq to record its process-id in. Normally /var/run/dnsmasq.pid. |
| 141 | .TP |
| 142 | .B \-u, --user=<username> |
| 143 | Specify the userid to which dnsmasq will change after startup. Dnsmasq must normally be started as root, but it will drop root |
Simon Kelley | b8187c8 | 2005-11-26 21:46:27 +0000 | [diff] [blame] | 144 | privileges after startup by changing id to another user. Normally this user is "nobody" but that |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 145 | can be over-ridden with this switch. |
| 146 | .TP |
| 147 | .B \-g, --group=<groupname> |
| 148 | Specify the group which dnsmasq will run |
| 149 | as. The defaults to "dip", if available, to facilitate access to |
| 150 | /etc/ppp/resolv.conf which is not normally world readable. |
| 151 | .TP |
| 152 | .B \-v, --version |
| 153 | Print the version number. |
| 154 | .TP |
| 155 | .B \-p, --port=<port> |
Simon Kelley | 824af85 | 2008-02-12 20:43:05 +0000 | [diff] [blame] | 156 | Listen on <port> instead of the standard DNS port (53). Setting this |
| 157 | to zero completely disables DNS function, leaving only DHCP and/or TFTP. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 158 | .TP |
Simon Kelley | feba5c1 | 2004-07-27 20:28:58 +0100 | [diff] [blame] | 159 | .B \-P, --edns-packet-max=<size> |
| 160 | Specify the largest EDNS.0 UDP packet which is supported by the DNS |
Simon Kelley | 316e273 | 2010-01-22 20:16:09 +0000 | [diff] [blame] | 161 | forwarder. Defaults to 4096, which is the RFC5625-recommended size. |
Simon Kelley | feba5c1 | 2004-07-27 20:28:58 +0100 | [diff] [blame] | 162 | .TP |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 163 | .B \-Q, --query-port=<query_port> |
Simon Kelley | 1a6bca8 | 2008-07-11 11:11:42 +0100 | [diff] [blame] | 164 | Send outbound DNS queries from, and listen for their replies on, the |
| 165 | specific UDP port <query_port> instead of using random ports. NOTE |
| 166 | that using this option will make dnsmasq less secure against DNS |
| 167 | spoofing attacks but it may be faster and use less resources. Setting this option |
| 168 | to zero makes dnsmasq use a single port allocated to it by the |
| 169 | OS: this was the default behaviour in versions prior to 2.43. |
| 170 | .TP |
| 171 | .B --min-port=<port> |
| 172 | Do not use ports less than that given as source for outbound DNS |
| 173 | queries. Dnsmasq picks random ports as source for outbound queries: |
| 174 | when this option is given, the ports used will always to larger |
| 175 | than that specified. Useful for systems behind firewalls. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 176 | .TP |
| 177 | .B \-i, --interface=<interface name> |
Simon Kelley | feba5c1 | 2004-07-27 20:28:58 +0100 | [diff] [blame] | 178 | Listen only on the specified interface(s). Dnsmasq automatically adds |
| 179 | the loopback (local) interface to the list of interfaces to use when |
| 180 | the |
| 181 | .B \--interface |
| 182 | option is used. If no |
| 183 | .B \--interface |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 184 | or |
Simon Kelley | feba5c1 | 2004-07-27 20:28:58 +0100 | [diff] [blame] | 185 | .B \--listen-address |
| 186 | options are given dnsmasq listens on all available interfaces except any |
| 187 | given in |
| 188 | .B \--except-interface |
Simon Kelley | 309331f | 2006-04-22 15:05:01 +0100 | [diff] [blame] | 189 | options. IP alias interfaces (eg "eth1:0") cannot be used with |
Simon Kelley | 8a911cc | 2004-03-16 18:35:52 +0000 | [diff] [blame] | 190 | .B --interface |
| 191 | or |
| 192 | .B --except-interface |
Simon Kelley | 49333cb | 2013-03-15 20:30:51 +0000 | [diff] [blame] | 193 | options, use --listen-address instead. A simple wildcard, consisting |
| 194 | of a trailing '*', can be used in |
| 195 | .B \--interface |
| 196 | and |
| 197 | .B \--except-interface |
| 198 | options. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 199 | .TP |
| 200 | .B \-I, --except-interface=<interface name> |
Simon Kelley | feba5c1 | 2004-07-27 20:28:58 +0100 | [diff] [blame] | 201 | Do not listen on the specified interface. Note that the order of |
| 202 | .B \--listen-address |
| 203 | .B --interface |
| 204 | and |
| 205 | .B --except-interface |
| 206 | options does not matter and that |
| 207 | .B --except-interface |
| 208 | options always override the others. |
Simon Kelley | 34d0a36 | 2013-01-02 11:40:56 +0000 | [diff] [blame] | 209 | .TP |
| 210 | .B --auth-server=<domain>,<interface>|<ip-address> |
Simon Kelley | 81925ab | 2013-04-10 11:43:58 +0100 | [diff] [blame] | 211 | Enable DNS authoritative mode for queries arriving at an interface or address. Note that the interface or address |
Simon Kelley | 34d0a36 | 2013-01-02 11:40:56 +0000 | [diff] [blame] | 212 | need not be mentioned in |
| 213 | .B --interface |
| 214 | or |
| 215 | .B --listen-address |
| 216 | configuration, indeed |
| 217 | .B --auth-server |
Simon Kelley | f25e6c6 | 2013-11-17 12:23:42 +0000 | [diff] [blame] | 218 | will overide these and provide a different DNS service on the |
| 219 | specified interface. The <domain> is the "glue record". It should |
| 220 | resolve in the global DNS to a A and/or AAAA record which points to |
| 221 | the address dnsmasq is listening on. When an interface is specified, |
| 222 | it may be qualified with "/4" or "/6" to specify only the IPv4 or IPv6 |
| 223 | addresses associated with the interface. |
Simon Kelley | c8a8048 | 2014-03-05 14:29:54 +0000 | [diff] [blame] | 224 | .TP |
| 225 | .B --local-service |
| 226 | Accept DNS queries only from hosts whose address is on a local subnet, |
| 227 | ie a subnet for which an interface exists on the server. This option |
| 228 | only has effect is there are no --interface --except-interface, |
| 229 | --listen-address or --auth-server options. It is intended to be set as |
| 230 | a default on installation, to allow unconfigured installations to be |
| 231 | useful but also safe from being used for DNS amplification attacks. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 232 | .TP |
Simon Kelley | 3d8df26 | 2005-08-29 12:19:27 +0100 | [diff] [blame] | 233 | .B \-2, --no-dhcp-interface=<interface name> |
Simon Kelley | 832af0b | 2007-01-21 20:01:28 +0000 | [diff] [blame] | 234 | Do not provide DHCP or TFTP on the specified interface, but do provide DNS service. |
Simon Kelley | 3d8df26 | 2005-08-29 12:19:27 +0100 | [diff] [blame] | 235 | .TP |
Simon Kelley | 44a2a31 | 2004-03-10 20:04:35 +0000 | [diff] [blame] | 236 | .B \-a, --listen-address=<ipaddr> |
Simon Kelley | feba5c1 | 2004-07-27 20:28:58 +0100 | [diff] [blame] | 237 | Listen on the given IP address(es). Both |
| 238 | .B \--interface |
| 239 | and |
| 240 | .B \--listen-address |
| 241 | options may be given, in which case the set of both interfaces and |
| 242 | addresses is used. Note that if no |
| 243 | .B \--interface |
| 244 | option is given, but |
| 245 | .B \--listen-address |
| 246 | is, dnsmasq will not automatically listen on the loopback |
| 247 | interface. To achieve this, its IP address, 127.0.0.1, must be |
| 248 | explicitly given as a |
| 249 | .B \--listen-address |
| 250 | option. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 251 | .TP |
Simon Kelley | 44a2a31 | 2004-03-10 20:04:35 +0000 | [diff] [blame] | 252 | .B \-z, --bind-interfaces |
| 253 | On systems which support it, dnsmasq binds the wildcard address, |
| 254 | even when it is listening on only some interfaces. It then discards |
| 255 | requests that it shouldn't reply to. This has the advantage of |
| 256 | working even when interfaces come and go and change address. This |
| 257 | option forces dnsmasq to really bind only the interfaces it is |
| 258 | listening on. About the only time when this is useful is when |
Simon Kelley | f6b7dc4 | 2005-01-23 12:06:08 +0000 | [diff] [blame] | 259 | running another nameserver (or another instance of dnsmasq) on the |
Simon Kelley | 309331f | 2006-04-22 15:05:01 +0100 | [diff] [blame] | 260 | same machine. Setting this option also enables multiple instances of |
Simon Kelley | f6b7dc4 | 2005-01-23 12:06:08 +0000 | [diff] [blame] | 261 | dnsmasq which provide DHCP service to run in the same machine. |
| 262 | .TP |
Simon Kelley | 54dd393 | 2012-06-20 11:23:38 +0100 | [diff] [blame] | 263 | .B --bind-dynamic |
| 264 | Enable a network mode which is a hybrid between |
| 265 | .B --bind-interfaces |
Simon Kelley | a2ce6fc | 2012-08-06 20:05:48 +0100 | [diff] [blame] | 266 | and the default. Dnsmasq binds the address of individual interfaces, |
Simon Kelley | 54dd393 | 2012-06-20 11:23:38 +0100 | [diff] [blame] | 267 | allowing multiple dnsmasq instances, but if new interfaces or |
| 268 | addresses appear, it automatically listens on those (subject to any |
| 269 | access-control configuration). This makes dynamically created |
| 270 | interfaces work in the same way as the default. Implementing this |
Simon Kelley | a2ce6fc | 2012-08-06 20:05:48 +0100 | [diff] [blame] | 271 | option requires non-standard networking APIs and it is only available |
Simon Kelley | 05ff1ed | 2012-06-26 16:58:12 +0100 | [diff] [blame] | 272 | under Linux. On other platforms it falls-back to --bind-interfaces mode. |
Simon Kelley | 54dd393 | 2012-06-20 11:23:38 +0100 | [diff] [blame] | 273 | .TP |
Simon Kelley | f6b7dc4 | 2005-01-23 12:06:08 +0000 | [diff] [blame] | 274 | .B \-y, --localise-queries |
| 275 | Return answers to DNS queries from /etc/hosts which depend on the interface over which the query was |
Simon Kelley | b8187c8 | 2005-11-26 21:46:27 +0000 | [diff] [blame] | 276 | received. If a name in /etc/hosts has more than one address associated with |
Simon Kelley | f6b7dc4 | 2005-01-23 12:06:08 +0000 | [diff] [blame] | 277 | it, and at least one of those addresses is on the same subnet as the |
| 278 | interface to which the query was sent, then return only the |
| 279 | address(es) on that subnet. This allows for a server to have multiple |
| 280 | addresses in /etc/hosts corresponding to each of its interfaces, and |
| 281 | hosts will get the correct address based on which network they are |
| 282 | attached to. Currently this facility is limited to IPv4. |
Simon Kelley | 44a2a31 | 2004-03-10 20:04:35 +0000 | [diff] [blame] | 283 | .TP |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 284 | .B \-b, --bogus-priv |
| 285 | Bogus private reverse lookups. All reverse lookups for private IP ranges (ie 192.168.x.x, etc) |
Simon Kelley | feba5c1 | 2004-07-27 20:28:58 +0100 | [diff] [blame] | 286 | which are not found in /etc/hosts or the DHCP leases file are answered |
| 287 | with "no such domain" rather than being forwarded upstream. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 288 | .TP |
Simon Kelley | 73a08a2 | 2009-02-05 20:28:08 +0000 | [diff] [blame] | 289 | .B \-V, --alias=[<old-ip>]|[<start-ip>-<end-ip>],<new-ip>[,<mask>] |
Simon Kelley | 1cff166 | 2004-03-12 08:12:58 +0000 | [diff] [blame] | 290 | Modify IPv4 addresses returned from upstream nameservers; old-ip is |
| 291 | replaced by new-ip. If the optional mask is given then any address |
| 292 | which matches the masked old-ip will be re-written. So, for instance |
| 293 | .B --alias=1.2.3.0,6.7.8.0,255.255.255.0 |
| 294 | will map 1.2.3.56 to 6.7.8.56 and 1.2.3.67 to 6.7.8.67. This is what |
Simon Kelley | 73a08a2 | 2009-02-05 20:28:08 +0000 | [diff] [blame] | 295 | Cisco PIX routers call "DNS doctoring". If the old IP is given as |
| 296 | range, then only addresses in the range, rather than a whole subnet, |
| 297 | are re-written. So |
| 298 | .B --alias=192.168.0.10-192.168.0.40,10.0.0.0,255.255.255.0 |
| 299 | maps 192.168.0.10->192.168.0.40 to 10.0.0.10->10.0.0.40 |
Simon Kelley | 1cff166 | 2004-03-12 08:12:58 +0000 | [diff] [blame] | 300 | .TP |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 301 | .B \-B, --bogus-nxdomain=<ipaddr> |
| 302 | Transform replies which contain the IP address given into "No such |
| 303 | domain" replies. This is intended to counteract a devious move made by |
Simon Kelley | b8187c8 | 2005-11-26 21:46:27 +0000 | [diff] [blame] | 304 | Verisign in September 2003 when they started returning the address of |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 305 | an advertising web page in response to queries for unregistered names, |
| 306 | instead of the correct NXDOMAIN response. This option tells dnsmasq to |
| 307 | fake the correct response when it sees this behaviour. As at Sept 2003 |
Simon Kelley | b8187c8 | 2005-11-26 21:46:27 +0000 | [diff] [blame] | 308 | the IP address being returned by Verisign is 64.94.110.11 |
Glen Huang | 32fc6db | 2014-12-27 15:28:12 +0000 | [diff] [blame] | 309 | .TP |
| 310 | .B \-B, --ignore-address=<ipaddr> |
| 311 | Ignore replies to A-record queries which include the specified address. |
| 312 | No error is generated, dnsmasq simply continues to listen for another reply. |
| 313 | This is useful to defeat blocking strategies which rely on quickly supplying a |
| 314 | forged answer to a DNS request for certain domain, before the correct answer can arrive. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 315 | .TP |
| 316 | .B \-f, --filterwin2k |
| 317 | Later versions of windows make periodic DNS requests which don't get sensible answers from |
| 318 | the public DNS and can cause problems by triggering dial-on-demand links. This flag turns on an option |
| 319 | to filter such requests. The requests blocked are for records of types SOA and SRV, and type ANY where the |
| 320 | requested name has underscores, to catch LDAP requests. |
| 321 | .TP |
| 322 | .B \-r, --resolv-file=<file> |
| 323 | Read the IP addresses of the upstream nameservers from <file>, instead of |
| 324 | /etc/resolv.conf. For the format of this file see |
Simon Kelley | 7de060b | 2011-08-26 17:24:52 +0100 | [diff] [blame] | 325 | .BR resolv.conf (5). |
| 326 | The only lines relevant to dnsmasq are nameserver ones. Dnsmasq can |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 327 | be told to poll more than one resolv.conf file, the first file name specified |
| 328 | overrides the default, subsequent ones add to the list. This is only |
| 329 | allowed when polling; the file with the currently latest modification |
| 330 | time is the one used. |
| 331 | .TP |
| 332 | .B \-R, --no-resolv |
| 333 | Don't read /etc/resolv.conf. Get upstream servers only from the command |
Simon Kelley | b49644f | 2004-01-30 21:36:24 +0000 | [diff] [blame] | 334 | line or the dnsmasq configuration file. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 335 | .TP |
Simon Kelley | ad09427 | 2012-08-10 17:10:54 +0100 | [diff] [blame] | 336 | .B \-1, --enable-dbus[=<service-name>] |
Simon Kelley | 3d8df26 | 2005-08-29 12:19:27 +0100 | [diff] [blame] | 337 | Allow dnsmasq configuration to be updated via DBus method calls. The |
| 338 | configuration which can be changed is upstream DNS servers (and |
Simon Kelley | b8187c8 | 2005-11-26 21:46:27 +0000 | [diff] [blame] | 339 | corresponding domains) and cache clear. Requires that dnsmasq has |
Simon Kelley | ad09427 | 2012-08-10 17:10:54 +0100 | [diff] [blame] | 340 | been built with DBus support. If the service name is given, dnsmasq |
| 341 | provides service at that name, rather than the default which is |
| 342 | .B uk.org.thekelleys.dnsmasq |
Simon Kelley | 3d8df26 | 2005-08-29 12:19:27 +0100 | [diff] [blame] | 343 | .TP |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 344 | .B \-o, --strict-order |
| 345 | By default, dnsmasq will send queries to any of the upstream servers |
Simon Kelley | 824af85 | 2008-02-12 20:43:05 +0000 | [diff] [blame] | 346 | it knows about and tries to favour servers that are known to |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 347 | be up. Setting this flag forces dnsmasq to try each query with each |
| 348 | server strictly in the order they appear in /etc/resolv.conf |
| 349 | .TP |
Simon Kelley | 824af85 | 2008-02-12 20:43:05 +0000 | [diff] [blame] | 350 | .B --all-servers |
| 351 | By default, when dnsmasq has more than one upstream server available, |
| 352 | it will send queries to just one server. Setting this flag forces |
| 353 | dnsmasq to send all queries to all available servers. The reply from |
Simon Kelley | c72daea | 2012-01-05 21:33:27 +0000 | [diff] [blame] | 354 | the server which answers first will be returned to the original requester. |
Simon Kelley | 824af85 | 2008-02-12 20:43:05 +0000 | [diff] [blame] | 355 | .TP |
Simon Kelley | b5ea1cc | 2014-07-29 16:34:14 +0100 | [diff] [blame] | 356 | .B --dns-loop-detect |
| 357 | Enable code to detect DNS forwarding loops; ie the situation where a query sent to one |
| 358 | of the upstream server eventually returns as a new query to the dnsmasq instance. The |
| 359 | process works by generating TXT queries of the form <hex>.test and sending them to |
| 360 | each upstream server. The hex is a UID which encodes the instance of dnsmasq sending the query |
| 361 | and the upstream server to which it was sent. If the query returns to the server which sent it, then |
| 362 | the upstream server through which it was sent is disabled and this event is logged. Each time the |
| 363 | set of upstream servers changes, the test is re-run on all of them, including ones which |
| 364 | were previously disabled. |
| 365 | .TP |
Simon Kelley | 824af85 | 2008-02-12 20:43:05 +0000 | [diff] [blame] | 366 | .B --stop-dns-rebind |
| 367 | Reject (and log) addresses from upstream nameservers which are in the |
| 368 | private IP ranges. This blocks an attack where a browser behind a |
| 369 | firewall is used to probe machines on the local network. |
| 370 | .TP |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 371 | .B --rebind-localhost-ok |
| 372 | Exempt 127.0.0.0/8 from rebinding checks. This address range is |
| 373 | returned by realtime black hole servers, so blocking it may disable |
| 374 | these services. |
| 375 | .TP |
| 376 | .B --rebind-domain-ok=[<domain>]|[[/<domain>/[<domain>/] |
| 377 | Do not detect and block dns-rebind on queries to these domains. The |
| 378 | argument may be either a single domain, or multiple domains surrounded |
| 379 | by '/', like the --server syntax, eg. |
| 380 | .B --rebind-domain-ok=/domain1/domain2/domain3/ |
| 381 | .TP |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 382 | .B \-n, --no-poll |
| 383 | Don't poll /etc/resolv.conf for changes. |
| 384 | .TP |
Simon Kelley | 1697269 | 2006-10-16 20:04:18 +0100 | [diff] [blame] | 385 | .B --clear-on-reload |
Simon Kelley | d9fb0be | 2013-07-25 21:47:17 +0100 | [diff] [blame] | 386 | Whenever /etc/resolv.conf is re-read or the upstream servers are set |
| 387 | via DBus, clear the DNS cache. |
Simon Kelley | 1697269 | 2006-10-16 20:04:18 +0100 | [diff] [blame] | 388 | This is useful when new nameservers may have different |
| 389 | data than that held in cache. |
| 390 | .TP |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 391 | .B \-D, --domain-needed |
Simon Kelley | 7de060b | 2011-08-26 17:24:52 +0100 | [diff] [blame] | 392 | Tells dnsmasq to never forward A or AAAA queries for plain names, without dots |
Simon Kelley | 3d8df26 | 2005-08-29 12:19:27 +0100 | [diff] [blame] | 393 | or domain parts, to upstream nameservers. If the name is not known |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 394 | from /etc/hosts or DHCP then a "not found" answer is returned. |
| 395 | .TP |
Simon Kelley | 824af85 | 2008-02-12 20:43:05 +0000 | [diff] [blame] | 396 | .B \-S, --local, --server=[/[<domain>]/[domain/]][<ipaddr>[#<port>][@<source-ip>|<interface>[#<port>]] |
Simon Kelley | 5aabfc7 | 2007-08-29 11:24:47 +0100 | [diff] [blame] | 397 | Specify IP address of upstream servers directly. Setting this flag does |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 398 | not suppress reading of /etc/resolv.conf, use -R to do that. If one or |
| 399 | more |
| 400 | optional domains are given, that server is used only for those domains |
| 401 | and they are queried only using the specified server. This is |
| 402 | intended for private nameservers: if you have a nameserver on your |
| 403 | network which deals with names of the form |
| 404 | xxx.internal.thekelleys.org.uk at 192.168.1.1 then giving the flag |
Simon Kelley | b8187c8 | 2005-11-26 21:46:27 +0000 | [diff] [blame] | 405 | .B -S /internal.thekelleys.org.uk/192.168.1.1 |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 406 | will send all queries for |
| 407 | internal machines to that nameserver, everything else will go to the |
| 408 | servers in /etc/resolv.conf. An empty domain specification, |
| 409 | .B // |
| 410 | has the special meaning of "unqualified names only" ie names without any |
| 411 | dots in them. A non-standard port may be specified as |
| 412 | part of the IP |
| 413 | address using a # character. |
| 414 | More than one -S flag is allowed, with |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 415 | repeated domain or ipaddr parts as required. |
| 416 | |
| 417 | More specific domains take precendence over less specific domains, so: |
| 418 | .B --server=/google.com/1.2.3.4 |
| 419 | .B --server=/www.google.com/2.3.4.5 |
| 420 | will send queries for *.google.com to 1.2.3.4, except *www.google.com, |
| 421 | which will go to 2.3.4.5 |
| 422 | |
| 423 | The special server address '#' means, "use the standard servers", so |
| 424 | .B --server=/google.com/1.2.3.4 |
| 425 | .B --server=/www.google.com/# |
| 426 | will send queries for *.google.com to 1.2.3.4, except *www.google.com which will |
| 427 | be forwarded as usual. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 428 | |
| 429 | Also permitted is a -S |
| 430 | flag which gives a domain but no IP address; this tells dnsmasq that |
| 431 | a domain is local and it may answer queries from /etc/hosts or DHCP |
| 432 | but should never forward queries on that domain to any upstream |
| 433 | servers. |
| 434 | .B local |
| 435 | is a synonym for |
| 436 | .B server |
| 437 | to make configuration files clearer in this case. |
| 438 | |
Simon Kelley | 7de060b | 2011-08-26 17:24:52 +0100 | [diff] [blame] | 439 | IPv6 addresses may include a %interface scope-id, eg |
| 440 | fe80::202:a412:4512:7bbf%eth0. |
| 441 | |
Simon Kelley | 824af85 | 2008-02-12 20:43:05 +0000 | [diff] [blame] | 442 | The optional string after the @ character tells |
| 443 | dnsmasq how to set the source of the queries to this |
| 444 | nameserver. It should be an ip-address, which should belong to the machine on which |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 445 | dnsmasq is running otherwise this server line will be logged and then |
Simon Kelley | 824af85 | 2008-02-12 20:43:05 +0000 | [diff] [blame] | 446 | ignored, or an interface name. If an interface name is given, then |
| 447 | queries to the server will be forced via that interface; if an |
| 448 | ip-address is given then the source address of the queries will be set |
| 449 | to that address. |
| 450 | The query-port flag is ignored for any servers which have a |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 451 | source address specified but the port may be specified directly as |
Simon Kelley | 824af85 | 2008-02-12 20:43:05 +0000 | [diff] [blame] | 452 | part of the source address. Forcing queries to an interface is not |
| 453 | implemented on all platforms supported by dnsmasq. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 454 | .TP |
Simon Kelley | de73a49 | 2014-02-17 21:43:27 +0000 | [diff] [blame] | 455 | .B --rev-server=<ip-address>/<prefix-len>,<ipaddr>[#<port>][@<source-ip>|<interface>[#<port>]] |
| 456 | This is functionally the same as |
| 457 | .B --server, |
| 458 | but provides some syntactic sugar to make specifying address-to-name queries easier. For example |
| 459 | .B --rev-server=1.2.3.0/24,192.168.0.1 |
| 460 | is exactly equivalent to |
| 461 | .B --server=/3.2.1.in-addr.arpa/192.168.0.1 |
| 462 | .TP |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 463 | .B \-A, --address=/<domain>/[domain/]<ipaddr> |
| 464 | Specify an IP address to return for any host in the given domains. |
| 465 | Queries in the domains are never forwarded and always replied to |
| 466 | with the specified IP address which may be IPv4 or IPv6. To give |
| 467 | both IPv4 and IPv6 addresses for a domain, use repeated -A flags. |
| 468 | Note that /etc/hosts and DHCP leases override this for individual |
| 469 | names. A common use of this is to redirect the entire doubleclick.net |
Simon Kelley | a222641 | 2004-05-13 20:27:08 +0100 | [diff] [blame] | 470 | domain to some friendly local web server to avoid banner ads. The |
| 471 | domain specification works in the same was as for --server, with the |
| 472 | additional facility that /#/ matches any domain. Thus |
| 473 | --address=/#/1.2.3.4 will always return 1.2.3.4 for any query not |
| 474 | answered from /etc/hosts or DHCP and not sent to an upstream |
| 475 | nameserver by a more specific --server directive. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 476 | .TP |
Jason A. Donenfeld | 13d86c7 | 2013-02-22 18:20:53 +0000 | [diff] [blame] | 477 | .B --ipset=/<domain>/[domain/]<ipset>[,<ipset>] |
| 478 | Places the resolved IP addresses of queries for the specified domains |
| 479 | in the specified netfilter ip sets. Domains and subdomains are matched |
| 480 | in the same way as --address. These ip sets must already exist. See |
| 481 | ipset(8) for more details. |
| 482 | .TP |
Simon Kelley | f6b7dc4 | 2005-01-23 12:06:08 +0000 | [diff] [blame] | 483 | .B \-m, --mx-host=<mx name>[[,<hostname>],<preference>] |
Simon Kelley | de37951 | 2004-06-22 20:23:33 +0100 | [diff] [blame] | 484 | Return an MX record named <mx name> pointing to the given hostname (if |
| 485 | given), or |
| 486 | the host specified in the --mx-target switch |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 487 | or, if that switch is not given, the host on which dnsmasq |
Simon Kelley | f6b7dc4 | 2005-01-23 12:06:08 +0000 | [diff] [blame] | 488 | is running. The default is useful for directing mail from systems on a LAN |
| 489 | to a central server. The preference value is optional, and defaults to |
| 490 | 1 if not given. More than one MX record may be given for a host. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 491 | .TP |
| 492 | .B \-t, --mx-target=<hostname> |
Simon Kelley | f6b7dc4 | 2005-01-23 12:06:08 +0000 | [diff] [blame] | 493 | Specify the default target for the MX record returned by dnsmasq. See |
| 494 | --mx-host. If --mx-target is given, but not --mx-host, then dnsmasq |
| 495 | returns a MX record containing the MX target for MX queries on the |
| 496 | hostname of the machine on which dnsmasq is running. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 497 | .TP |
| 498 | .B \-e, --selfmx |
| 499 | Return an MX record pointing to itself for each local |
| 500 | machine. Local machines are those in /etc/hosts or with DHCP leases. |
| 501 | .TP |
| 502 | .B \-L, --localmx |
| 503 | Return an MX record pointing to the host given by mx-target (or the |
| 504 | machine on which dnsmasq is running) for each |
| 505 | local machine. Local machines are those in /etc/hosts or with DHCP |
| 506 | leases. |
| 507 | .TP |
Simon Kelley | f6b7dc4 | 2005-01-23 12:06:08 +0000 | [diff] [blame] | 508 | .B \-W, --srv-host=<_service>.<_prot>.[<domain>],[<target>[,<port>[,<priority>[,<weight>]]]] |
| 509 | Return a SRV DNS record. See RFC2782 for details. If not supplied, the |
| 510 | domain defaults to that given by |
| 511 | .B --domain. |
| 512 | The default for the target domain is empty, and the default for port |
| 513 | is one and the defaults for |
| 514 | weight and priority are zero. Be careful if transposing data from BIND |
| 515 | zone files: the port, weight and priority numbers are in a different |
| 516 | order. More than one SRV record for a given service/domain is allowed, |
Simon Kelley | 3d8df26 | 2005-08-29 12:19:27 +0100 | [diff] [blame] | 517 | all that match are returned. |
Simon Kelley | f6b7dc4 | 2005-01-23 12:06:08 +0000 | [diff] [blame] | 518 | .TP |
Thiébaud Weksteen | d36b732 | 2015-02-02 21:37:27 +0000 | [diff] [blame^] | 519 | .B --host-record=<name>[,<name>....],[<IPv4-address>],[<IPv6-address>] |
Simon Kelley | e759d42 | 2012-03-16 13:18:57 +0000 | [diff] [blame] | 520 | Add A, AAAA and PTR records to the DNS. This adds one or more names to |
| 521 | the DNS with associated IPv4 (A) and IPv6 (AAAA) records. A name may |
| 522 | appear in more than one |
| 523 | .B host-record |
| 524 | and therefore be assigned more than one address. Only the first |
| 525 | address creates a PTR record linking the address to the name. This is |
| 526 | the same rule as is used reading hosts-files. |
| 527 | .B host-record |
| 528 | options are considered to be read before host-files, so a name |
| 529 | appearing there inhibits PTR-record creation if it appears in |
Simon Kelley | e46164e | 2012-04-16 16:39:38 +0100 | [diff] [blame] | 530 | hosts-file also. Unlike hosts-files, names are not expanded, even when |
Simon Kelley | e759d42 | 2012-03-16 13:18:57 +0000 | [diff] [blame] | 531 | .B expand-hosts |
| 532 | is in effect. Short and long names may appear in the same |
Simon Kelley | e46164e | 2012-04-16 16:39:38 +0100 | [diff] [blame] | 533 | .B host-record, |
| 534 | eg. |
| 535 | .B --host-record=laptop,laptop.thekelleys.org,192.168.0.1,1234::100 |
Simon Kelley | e759d42 | 2012-03-16 13:18:57 +0000 | [diff] [blame] | 536 | .TP |
Simon Kelley | 0a85254 | 2005-03-23 20:28:59 +0000 | [diff] [blame] | 537 | .B \-Y, --txt-record=<name>[[,<text>],<text>] |
| 538 | Return a TXT DNS record. The value of TXT record is a set of strings, |
Simon Kelley | 28866e9 | 2011-02-14 20:19:14 +0000 | [diff] [blame] | 539 | so any number may be included, delimited by commas; use quotes to put |
| 540 | commas into a string. Note that the maximum length of a single string |
| 541 | is 255 characters, longer strings are split into 255 character chunks. |
Simon Kelley | 0a85254 | 2005-03-23 20:28:59 +0000 | [diff] [blame] | 542 | .TP |
Simon Kelley | 832af0b | 2007-01-21 20:01:28 +0000 | [diff] [blame] | 543 | .B --ptr-record=<name>[,<target>] |
| 544 | Return a PTR DNS record. |
| 545 | .TP |
Simon Kelley | 1a6bca8 | 2008-07-11 11:11:42 +0100 | [diff] [blame] | 546 | .B --naptr-record=<name>,<order>,<preference>,<flags>,<service>,<regexp>[,<replacement>] |
| 547 | Return an NAPTR DNS record, as specified in RFC3403. |
| 548 | .TP |
Simon Kelley | 9009d74 | 2008-11-14 20:04:27 +0000 | [diff] [blame] | 549 | .B --cname=<cname>,<target> |
| 550 | Return a CNAME record which indicates that <cname> is really |
| 551 | <target>. There are significant limitations on the target; it must be a |
| 552 | DNS name which is known to dnsmasq from /etc/hosts (or additional |
Simon Kelley | d56a604 | 2013-10-11 14:39:03 +0100 | [diff] [blame] | 553 | hosts files), from DHCP, from --interface-name or from another |
Simon Kelley | 611ebc5 | 2012-07-16 16:23:46 +0100 | [diff] [blame] | 554 | .B --cname. |
| 555 | If the target does not satisfy this |
Simon Kelley | 9009d74 | 2008-11-14 20:04:27 +0000 | [diff] [blame] | 556 | criteria, the whole cname is ignored. The cname must be unique, but it |
| 557 | is permissable to have more than one cname pointing to the same target. |
| 558 | .TP |
Simon Kelley | 9f7f3b1 | 2012-05-28 21:39:57 +0100 | [diff] [blame] | 559 | .B --dns-rr=<name>,<RR-number>,[<hex data>] |
| 560 | Return an arbitrary DNS Resource Record. The number is the type of the |
| 561 | record (which is always in the C_IN class). The value of the record is |
Simon Kelley | a2ce6fc | 2012-08-06 20:05:48 +0100 | [diff] [blame] | 562 | given by the hex data, which may be of the form 01:23:45 or 01 23 45 or |
Simon Kelley | 9f7f3b1 | 2012-05-28 21:39:57 +0100 | [diff] [blame] | 563 | 012345 or any mixture of these. |
| 564 | .TP |
Simon Kelley | f7029f5 | 2013-11-21 15:09:09 +0000 | [diff] [blame] | 565 | .B --interface-name=<name>,<interface>[/4|/6] |
Simon Kelley | f2621c7 | 2007-04-29 19:47:21 +0100 | [diff] [blame] | 566 | Return a DNS record associating the name with the primary address on |
Simon Kelley | f7029f5 | 2013-11-21 15:09:09 +0000 | [diff] [blame] | 567 | the given interface. This flag specifies an A or AAAA record for the given |
Simon Kelley | f2621c7 | 2007-04-29 19:47:21 +0100 | [diff] [blame] | 568 | name in the same way as an /etc/hosts line, except that the address is |
Simon Kelley | f7029f5 | 2013-11-21 15:09:09 +0000 | [diff] [blame] | 569 | not constant, but taken from the given interface. The interface may be |
| 570 | followed by "/4" or "/6" to specify that only IPv4 or IPv6 addresses |
| 571 | of the interface should be used. If the interface is |
Simon Kelley | 9e03894 | 2008-05-30 20:06:34 +0100 | [diff] [blame] | 572 | down, not configured or non-existent, an empty record is returned. The |
Simon Kelley | f2621c7 | 2007-04-29 19:47:21 +0100 | [diff] [blame] | 573 | matching PTR record is also created, mapping the interface address to |
| 574 | the name. More than one name may be associated with an interface |
| 575 | address by repeating the flag; in that case the first instance is used |
| 576 | for the reverse address-to-name mapping. |
| 577 | .TP |
Simon Kelley | 48fd1c4 | 2013-04-25 09:49:38 +0100 | [diff] [blame] | 578 | .B --synth-domain=<domain>,<address range>[,<prefix>] |
Simon Kelley | 2bb73af | 2013-04-24 17:38:19 +0100 | [diff] [blame] | 579 | Create artificial A/AAAA and PTR records for an address range. The |
| 580 | records use the address, with periods (or colons for IPv6) replaced |
| 581 | with dashes. |
| 582 | |
| 583 | An example should make this clearer. |
Simon Kelley | 48fd1c4 | 2013-04-25 09:49:38 +0100 | [diff] [blame] | 584 | .B --synth-domain=thekelleys.org.uk,192.168.0.0/24,internal- |
| 585 | will result in a query for internal-192-168-0-56.thekelleys.org.uk returning |
| 586 | 192.168.0.56 and a reverse query vice versa. The same applies to IPv6, |
| 587 | but IPv6 addresses may start with '::' |
| 588 | but DNS labels may not start with '-' so in this case if no prefix is |
| 589 | configured a zero is added in front of the label. ::1 becomes 0--1. |
Simon Kelley | 2bb73af | 2013-04-24 17:38:19 +0100 | [diff] [blame] | 590 | |
| 591 | The address range can be of the form |
| 592 | <ip address>,<ip address> or <ip address>/<netmask> |
| 593 | .TP |
Simon Kelley | 28866e9 | 2011-02-14 20:19:14 +0000 | [diff] [blame] | 594 | .B --add-mac |
| 595 | Add the MAC address of the requestor to DNS queries which are |
| 596 | forwarded upstream. This may be used to DNS filtering by the upstream |
| 597 | server. The MAC address can only be added if the requestor is on the same |
| 598 | subnet as the dnsmasq server. Note that the mechanism used to achieve this (an EDNS0 option) |
| 599 | is not yet standardised, so this should be considered |
| 600 | experimental. Also note that exposing MAC addresses in this way may |
Simon Kelley | ed4c076 | 2013-10-08 20:46:34 +0100 | [diff] [blame] | 601 | have security and privacy implications. The warning about caching |
| 602 | given for --add-subnet applies to --add-mac too. |
| 603 | .TP |
| 604 | .B --add-subnet[[=<IPv4 prefix length>],<IPv6 prefix length>] |
| 605 | Add the subnet address of the requestor to the DNS queries which are |
| 606 | forwarded upstream. The amount of the address forwarded depends on the |
| 607 | prefix length parameter: 32 (128 for IPv6) forwards the whole address, |
| 608 | zero forwards none of it but still marks the request so that no |
| 609 | upstream nameserver will add client address information either. The |
| 610 | default is zero for both IPv4 and IPv6. Note that upstream nameservers |
| 611 | may be configured to return different results based on this |
| 612 | information, but the dnsmasq cache does not take account. If a dnsmasq |
| 613 | instance is configured such that different results may be encountered, |
| 614 | caching should be disabled. |
Simon Kelley | 28866e9 | 2011-02-14 20:19:14 +0000 | [diff] [blame] | 615 | .TP |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 616 | .B \-c, --cache-size=<cachesize> |
| 617 | Set the size of dnsmasq's cache. The default is 150 names. Setting the cache size to zero disables caching. |
| 618 | .TP |
| 619 | .B \-N, --no-negcache |
| 620 | Disable negative caching. Negative caching allows dnsmasq to remember |
| 621 | "no such domain" answers from upstream nameservers and answer |
Simon Kelley | 5aabfc7 | 2007-08-29 11:24:47 +0100 | [diff] [blame] | 622 | identical queries without forwarding them again. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 623 | .TP |
Simon Kelley | 1697269 | 2006-10-16 20:04:18 +0100 | [diff] [blame] | 624 | .B \-0, --dns-forward-max=<queries> |
| 625 | Set the maximum number of concurrent DNS queries. The default value is |
| 626 | 150, which should be fine for most setups. The only known situation |
| 627 | where this needs to be increased is when using web-server log file |
| 628 | resolvers, which can generate large numbers of concurrent queries. |
Simon Kelley | 208b65c | 2006-08-05 21:41:37 +0100 | [diff] [blame] | 629 | .TP |
Simon Kelley | 70b4a81 | 2014-01-27 22:38:48 +0000 | [diff] [blame] | 630 | .B --dnssec |
| 631 | Validate DNS replies and cache DNSSEC data. When forwarding DNS queries, dnsmasq requests the |
| 632 | DNSSEC records needed to validate the replies. The replies are validated and the result returned as |
| 633 | the Authenticated Data bit in the DNS packet. In addition the DNSSEC records are stored in the cache, making |
| 634 | validation by clients more efficient. Note that validation by clients is the most secure DNSSEC mode, but for |
| 635 | clients unable to do validation, use of the AD bit set by dnsmasq is useful, provided that the network between |
| 636 | the dnsmasq server and the client is trusted. Dnsmasq must be compiled with HAVE_DNSSEC enabled, and DNSSEC |
| 637 | trust anchors provided, see |
Simon Kelley | ee41586 | 2014-02-11 11:07:22 +0000 | [diff] [blame] | 638 | .B --trust-anchor. |
Simon Kelley | d588ab5 | 2014-03-02 14:30:05 +0000 | [diff] [blame] | 639 | Because the DNSSEC validation process uses the cache, it is not |
| 640 | permitted to reduce the cache size below the default when DNSSEC is |
| 641 | enabled. The nameservers upstream of dnsmasq must be DNSSEC-capable, |
| 642 | ie capable of returning DNSSEC records with data. If they are not, |
| 643 | then dnsmasq will not be able to determine the trusted status of |
| 644 | answers. In the default mode, this menas that all replies will be |
| 645 | marked as untrusted. If |
| 646 | .B --dnssec-check-unsigned |
| 647 | is set and the upstream servers don't support DNSSEC, then DNS service will be entirely broken. |
Simon Kelley | 70b4a81 | 2014-01-27 22:38:48 +0000 | [diff] [blame] | 648 | .TP |
Simon Kelley | ee41586 | 2014-02-11 11:07:22 +0000 | [diff] [blame] | 649 | .B --trust-anchor=[<class>],<domain>,<key-tag>,<algorithm>,<digest-type>,<digest> |
| 650 | Provide DS records to act a trust anchors for DNSSEC |
| 651 | validation. Typically these will be the DS record(s) for Zone Signing |
| 652 | key(s) of the root zone, |
| 653 | but trust anchors for limited domains are also possible. The current |
| 654 | root-zone trust anchors may be donwloaded from https://data.iana.org/root-anchors/root-anchors.xml |
Simon Kelley | 70b4a81 | 2014-01-27 22:38:48 +0000 | [diff] [blame] | 655 | .TP |
Simon Kelley | 00a5b5d | 2014-02-28 18:10:55 +0000 | [diff] [blame] | 656 | .B --dnssec-check-unsigned |
| 657 | As a default, dnsmasq does not check that unsigned DNS replies are |
| 658 | legitimate: they are assumed to be valid and passed on (without the |
| 659 | "authentic data" bit set, of course). This does not protect against an |
| 660 | attacker forging unsigned replies for signed DNS zones, but it is |
| 661 | fast. If this flag is set, dnsmasq will check the zones of unsigned |
| 662 | replies, to ensure that unsigned replies are allowed in those |
Simon Kelley | d588ab5 | 2014-03-02 14:30:05 +0000 | [diff] [blame] | 663 | zones. The cost of this is more upstream queries and slower |
| 664 | performance. See also the warning about upstream servers in the |
| 665 | section on |
| 666 | .B --dnssec |
Simon Kelley | 00a5b5d | 2014-02-28 18:10:55 +0000 | [diff] [blame] | 667 | .TP |
Simon Kelley | e98bd52 | 2014-03-28 20:41:23 +0000 | [diff] [blame] | 668 | .B --dnssec-no-timecheck |
| 669 | DNSSEC signatures are only valid for specified time windows, and should be rejected outside those windows. This generates an |
| 670 | interesting chicken-and-egg problem for machines which don't have a hardware real time clock. For these machines to determine the correct |
| 671 | time typically requires use of NTP and therefore DNS, but validating DNS requires that the correct time is already known. Setting this flag |
| 672 | removes the time-window checks (but not other DNSSEC validation.) only until the dnsmasq process receives SIGHUP. The intention is |
| 673 | that dnsmasq should be started with this flag when the platform determines that reliable time is not currently available. As soon as |
| 674 | reliable time is established, a SIGHUP should be sent to dnsmasq, which enables time checking, and purges the cache of DNS records |
| 675 | which have not been throughly checked. |
| 676 | .TP |
Simon Kelley | 28866e9 | 2011-02-14 20:19:14 +0000 | [diff] [blame] | 677 | .B --proxy-dnssec |
Simon Kelley | 70b4a81 | 2014-01-27 22:38:48 +0000 | [diff] [blame] | 678 | Copy the DNSSEC Authenticated Data bit from upstream servers to downstream clients and cache it. This is an |
| 679 | alternative to having dnsmasq validate DNSSEC, but it depends on the security of the network between |
| 680 | dnsmasq and the upstream servers, and the trustworthiness of the upstream servers. |
| 681 | .TP |
| 682 | .B --dnssec-debug |
| 683 | Set debugging mode for the DNSSEC validation, set the Checking Disabled bit on upstream queries, |
Simon Kelley | ee41586 | 2014-02-11 11:07:22 +0000 | [diff] [blame] | 684 | and don't convert replies which do not validate to responses with |
| 685 | a return code of SERVFAIL. Note that |
| 686 | setting this may affect DNS behaviour in bad ways, it is not an |
| 687 | extra-logging flag and should not be set in production. |
Simon Kelley | 28866e9 | 2011-02-14 20:19:14 +0000 | [diff] [blame] | 688 | .TP |
Simon Kelley | baa80ae | 2013-05-29 16:32:07 +0100 | [diff] [blame] | 689 | .B --auth-zone=<domain>[,<subnet>[/<prefix length>][,<subnet>[/<prefix length>].....]] |
Simon Kelley | 34d0a36 | 2013-01-02 11:40:56 +0000 | [diff] [blame] | 690 | Define a DNS zone for which dnsmasq acts as authoritative server. Locally defined DNS records which are in the domain |
Simon Kelley | c50f25a | 2013-11-21 11:29:27 +0000 | [diff] [blame] | 691 | will be served. If subnet(s) are given, A and AAAA records must be in one of the |
| 692 | specified subnets. |
| 693 | |
| 694 | As alternative to directly specifying the subnets, it's possible to |
Simon Kelley | 376d48c | 2013-11-13 13:04:30 +0000 | [diff] [blame] | 695 | give the name of an interface, in which case the subnets implied by |
| 696 | that interface's configured addresses and netmask/prefix-length are |
| 697 | used; this is useful when using constructed DHCP ranges as the actual |
| 698 | address is dynamic and not known when configuring dnsmasq. The |
| 699 | interface addresses may be confined to only IPv6 addresses using |
| 700 | <interface>/6 or to only IPv4 using <interface>/4. This is useful when |
| 701 | an interface has dynamically determined global IPv6 addresses which should |
| 702 | appear in the zone, but RFC1918 IPv4 addresses which should not. |
| 703 | Interface-name and address-literal subnet specifications may be used |
| 704 | freely in the same --auth-zone declaration. |
| 705 | |
| 706 | The subnet(s) are also used to define in-addr.arpa and |
Lutz Preßler | 1d7e0a3 | 2014-04-07 22:06:23 +0100 | [diff] [blame] | 707 | ip6.arpa domains which are served for reverse-DNS queries. If not |
Simon Kelley | baa80ae | 2013-05-29 16:32:07 +0100 | [diff] [blame] | 708 | specified, the prefix length defaults to 24 for IPv4 and 64 for IPv6. |
| 709 | For IPv4 subnets, the prefix length should be have the value 8, 16 or 24 |
| 710 | unless you are familiar with RFC 2317 and have arranged the |
Simon Kelley | c50f25a | 2013-11-21 11:29:27 +0000 | [diff] [blame] | 711 | in-addr.arpa delegation accordingly. Note that if no subnets are |
| 712 | specified, then no reverse queries are answered. |
Simon Kelley | 333b2ce | 2013-01-07 21:46:03 +0000 | [diff] [blame] | 713 | .TP |
| 714 | .B --auth-soa=<serial>[,<hostmaster>[,<refresh>[,<retry>[,<expiry>]]]] |
| 715 | Specify fields in the SOA record associated with authoritative |
| 716 | zones. Note that this is optional, all the values are set to sane defaults. |
| 717 | .TP |
| 718 | .B --auth-sec-servers=<domain>[,<domain>[,<domain>...]] |
| 719 | Specify any secondary servers for a zone for which dnsmasq is |
| 720 | authoritative. These servers must be configured to get zone data from |
| 721 | dnsmasq by zone transfer, and answer queries for the same |
Simon Kelley | 6f130de | 2013-04-15 14:47:14 +0100 | [diff] [blame] | 722 | authoritative zones as dnsmasq. |
Simon Kelley | 333b2ce | 2013-01-07 21:46:03 +0000 | [diff] [blame] | 723 | .TP |
| 724 | .B --auth-peer=<ip-address>[,<ip-address>[,<ip-address>...]] |
| 725 | Specify the addresses of secondary servers which are allowed to |
| 726 | initiate zone transfer (AXFR) requests for zones for which dnsmasq is |
Simon Kelley | 6f130de | 2013-04-15 14:47:14 +0100 | [diff] [blame] | 727 | authoritative. If this option is not given, then AXFR requests will be |
Simon Kelley | 333b2ce | 2013-01-07 21:46:03 +0000 | [diff] [blame] | 728 | accepted from any secondary. |
| 729 | .TP |
Simon Kelley | 7de060b | 2011-08-26 17:24:52 +0100 | [diff] [blame] | 730 | .B --conntrack |
| 731 | Read the Linux connection track mark associated with incoming DNS |
| 732 | queries and set the same mark value on upstream traffic used to answer |
| 733 | those queries. This allows traffic generated by dnsmasq to be |
| 734 | associated with the queries which cause it, useful for bandwidth |
| 735 | accounting and firewalling. Dnsmasq must have conntrack support |
| 736 | compiled in and the kernel must have conntrack support |
| 737 | included and configured. This option cannot be combined with |
| 738 | --query-port. |
| 739 | .TP |
Simon Kelley | 49dc570 | 2013-04-02 20:27:07 +0100 | [diff] [blame] | 740 | .B \-F, --dhcp-range=[tag:<tag>[,tag:<tag>],][set:<tag>,]<start-addr>[,<end-addr>][,<mode>][,<netmask>[,<broadcast>]][,<lease time>] |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 741 | .TP |
Simon Kelley | 83f28be | 2013-04-03 14:46:46 +0100 | [diff] [blame] | 742 | .B \-F, --dhcp-range=[tag:<tag>[,tag:<tag>],][set:<tag>,]<start-IPv6addr>[,<end-IPv6addr>|constructor:<interface>][,<mode>][,<prefix-len>][,<lease time>] |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 743 | |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 744 | Enable the DHCP server. Addresses will be given out from the range |
Simon Kelley | 44a2a31 | 2004-03-10 20:04:35 +0000 | [diff] [blame] | 745 | <start-addr> to <end-addr> and from statically defined addresses given |
| 746 | in |
| 747 | .B dhcp-host |
| 748 | options. If the lease time is given, then leases |
Simon Kelley | b8187c8 | 2005-11-26 21:46:27 +0000 | [diff] [blame] | 749 | will be given for that length of time. The lease time is in seconds, |
Simon Kelley | 7622fc0 | 2009-06-04 20:32:05 +0100 | [diff] [blame] | 750 | or minutes (eg 45m) or hours (eg 1h) or "infinite". If not given, |
| 751 | the default lease time is one hour. The |
Simon Kelley | c825754 | 2012-03-28 21:15:41 +0100 | [diff] [blame] | 752 | minimum lease time is two minutes. For IPv6 ranges, the lease time |
| 753 | maybe "deprecated"; this sets the preferred lifetime sent in a DHCP |
| 754 | lease or router advertisement to zero, which causes clients to use |
| 755 | other addresses, if available, for new connections as a prelude to renumbering. |
| 756 | |
| 757 | This option may be repeated, with different addresses, to enable DHCP |
Simon Kelley | 44a2a31 | 2004-03-10 20:04:35 +0000 | [diff] [blame] | 758 | service to more than one network. For directly connected networks (ie, |
| 759 | networks on which the machine running dnsmasq has an interface) the |
Simon Kelley | 7de060b | 2011-08-26 17:24:52 +0100 | [diff] [blame] | 760 | netmask is optional: dnsmasq will determine it from the interface |
| 761 | configuration. For networks which receive DHCP service via a relay |
| 762 | agent, dnsmasq cannot determine the netmask itself, so it should be |
| 763 | specified, otherwise dnsmasq will have to guess, based on the class (A, B or |
| 764 | C) of the network address. The broadcast address is |
Simon Kelley | 7622fc0 | 2009-06-04 20:32:05 +0100 | [diff] [blame] | 765 | always optional. It is always |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 766 | allowed to have more than one dhcp-range in a single subnet. |
| 767 | |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 768 | For IPv6, the parameters are slightly different: instead of netmask |
Vladislav Grishenko | 4c82efc | 2013-12-03 16:05:30 +0000 | [diff] [blame] | 769 | and broadcast address, there is an optional prefix length which must |
| 770 | be equal to or larger then the prefix length on the local interface. If not |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 771 | given, this defaults to 64. Unlike the IPv4 case, the prefix length is not |
| 772 | automatically derived from the interface configuration. The mimimum |
| 773 | size of the prefix length is 64. |
| 774 | |
Simon Kelley | 34d0a36 | 2013-01-02 11:40:56 +0000 | [diff] [blame] | 775 | IPv6 (only) supports another type of range. In this, the start address and optional end address contain only the network part (ie ::1) and they are followed by |
| 776 | .B constructor:<interface>. |
| 777 | This forms a template which describes how to create ranges, based on the addresses assigned to the interface. For instance |
| 778 | |
Simon Kelley | 83f28be | 2013-04-03 14:46:46 +0100 | [diff] [blame] | 779 | .B --dhcp-range=::1,::400,constructor:eth0 |
Simon Kelley | 34d0a36 | 2013-01-02 11:40:56 +0000 | [diff] [blame] | 780 | |
Simon Kelley | 861c891 | 2013-09-25 15:30:30 +0100 | [diff] [blame] | 781 | will look for addresses on |
Simon Kelley | 429805d | 2013-05-31 13:47:26 +0100 | [diff] [blame] | 782 | eth0 and then create a range from <network>::1 to <network>::400. If |
| 783 | the interface is assigned more than one network, then the |
| 784 | corresponding ranges will be automatically created, and then |
| 785 | deprecated and finally removed again as the address is deprecated and |
| 786 | then deleted. The interface name may have a final "*" wildcard. Note |
Simon Kelley | 861c891 | 2013-09-25 15:30:30 +0100 | [diff] [blame] | 787 | that just any address on eth0 will not do: it must not be an |
| 788 | autoconfigured or privacy address, or be deprecated. |
Simon Kelley | 34d0a36 | 2013-01-02 11:40:56 +0000 | [diff] [blame] | 789 | |
Vladislav Grishenko | e4cdbbf | 2013-08-19 16:20:31 +0100 | [diff] [blame] | 790 | If a dhcp-range is only being used for stateless DHCP and/or SLAAC, |
| 791 | then the address can be simply :: |
| 792 | |
| 793 | .B --dhcp-range=::,constructor:eth0 |
| 794 | |
Vladislav Grishenko | e4cdbbf | 2013-08-19 16:20:31 +0100 | [diff] [blame] | 795 | |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 796 | The optional |
| 797 | .B set:<tag> |
| 798 | sets an alphanumeric label which marks this network so that |
Simon Kelley | 0a85254 | 2005-03-23 20:28:59 +0000 | [diff] [blame] | 799 | dhcp options may be specified on a per-network basis. |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 800 | When it is prefixed with 'tag:' instead, then its meaning changes from setting |
Simon Kelley | c5ad4e7 | 2012-02-24 16:06:20 +0000 | [diff] [blame] | 801 | a tag to matching it. Only one tag may be set, but more than one tag |
| 802 | may be matched. |
| 803 | |
Simon Kelley | e8ca69e | 2012-03-26 21:23:26 +0100 | [diff] [blame] | 804 | The optional <mode> keyword may be |
Simon Kelley | 33820b7 | 2004-04-03 21:10:00 +0100 | [diff] [blame] | 805 | .B static |
| 806 | which tells dnsmasq to enable DHCP for the network specified, but not |
Simon Kelley | 7622fc0 | 2009-06-04 20:32:05 +0100 | [diff] [blame] | 807 | to dynamically allocate IP addresses: only hosts which have static |
Simon Kelley | 33820b7 | 2004-04-03 21:10:00 +0100 | [diff] [blame] | 808 | addresses given via |
| 809 | .B dhcp-host |
Simon Kelley | 5200205 | 2012-10-26 11:39:02 +0100 | [diff] [blame] | 810 | or from /etc/ethers will be served. A static-only subnet with address |
| 811 | all zeros may be used as a "catch-all" address to enable replies to all |
| 812 | Information-request packets on a subnet which is provided with |
| 813 | stateless DHCPv6, ie |
Moritz Warning | e62e9b6 | 2014-03-20 15:32:22 +0000 | [diff] [blame] | 814 | .B --dhcp-range=::,static |
Simon Kelley | c5ad4e7 | 2012-02-24 16:06:20 +0000 | [diff] [blame] | 815 | |
Simon Kelley | e46164e | 2012-04-16 16:39:38 +0100 | [diff] [blame] | 816 | For IPv4, the <mode> may be |
Simon Kelley | 7622fc0 | 2009-06-04 20:32:05 +0100 | [diff] [blame] | 817 | .B proxy |
| 818 | in which case dnsmasq will provide proxy-DHCP on the specified |
| 819 | subnet. (See |
| 820 | .B pxe-prompt |
| 821 | and |
| 822 | .B pxe-service |
Simon Kelley | e8ca69e | 2012-03-26 21:23:26 +0100 | [diff] [blame] | 823 | for details.) |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 824 | |
Simon Kelley | e8ca69e | 2012-03-26 21:23:26 +0100 | [diff] [blame] | 825 | For IPv6, the mode may be some combination of |
Simon Kelley | 7ea3d3f | 2014-04-25 22:04:05 +0100 | [diff] [blame] | 826 | .B ra-only, slaac, ra-names, ra-stateless, ra-advrouter. |
Simon Kelley | e8ca69e | 2012-03-26 21:23:26 +0100 | [diff] [blame] | 827 | |
Simon Kelley | c5ad4e7 | 2012-02-24 16:06:20 +0000 | [diff] [blame] | 828 | .B ra-only |
Simon Kelley | e8ca69e | 2012-03-26 21:23:26 +0100 | [diff] [blame] | 829 | tells dnsmasq to offer Router Advertisement only on this subnet, |
| 830 | and not DHCP. |
| 831 | |
| 832 | .B slaac |
| 833 | tells dnsmasq to offer Router Advertisement on this subnet and to set |
| 834 | the A bit in the router advertisement, so that the client will use |
| 835 | SLAAC addresses. When used with a DHCP range or static DHCP address |
| 836 | this results in the client having both a DHCP-assigned and a SLAAC |
| 837 | address. |
| 838 | |
| 839 | .B ra-stateless |
| 840 | sends router advertisements with the O and A bits set, and provides a |
| 841 | stateless DHCP service. The client will use a SLAAC address, and use |
| 842 | DHCP for other configuration information. |
| 843 | |
Simon Kelley | 7023e38 | 2012-03-09 12:05:49 +0000 | [diff] [blame] | 844 | .B ra-names |
Simon Kelley | e8ca69e | 2012-03-26 21:23:26 +0100 | [diff] [blame] | 845 | enables a mode |
Simon Kelley | 7023e38 | 2012-03-09 12:05:49 +0000 | [diff] [blame] | 846 | which gives DNS names to dual-stack hosts which do SLAAC for |
Simon Kelley | 884a6df | 2012-03-20 16:20:22 +0000 | [diff] [blame] | 847 | IPv6. Dnsmasq uses the host's IPv4 lease to derive the name, network |
Simon Kelley | 7023e38 | 2012-03-09 12:05:49 +0000 | [diff] [blame] | 848 | segment and MAC address and assumes that the host will also have an |
Simon Kelley | e46164e | 2012-04-16 16:39:38 +0100 | [diff] [blame] | 849 | IPv6 address calculated using the SLAAC algorithm, on the same network |
Simon Kelley | 884a6df | 2012-03-20 16:20:22 +0000 | [diff] [blame] | 850 | segment. The address is pinged, and if a reply is received, an AAAA |
| 851 | record is added to the DNS for this IPv6 |
Simon Kelley | 7023e38 | 2012-03-09 12:05:49 +0000 | [diff] [blame] | 852 | address. Note that this is only happens for directly-connected |
Simon Kelley | 884a6df | 2012-03-20 16:20:22 +0000 | [diff] [blame] | 853 | networks, (not one doing DHCP via a relay) and it will not work |
| 854 | if a host is using privacy extensions. |
Simon Kelley | e8ca69e | 2012-03-26 21:23:26 +0100 | [diff] [blame] | 855 | .B ra-names |
| 856 | can be combined with |
| 857 | .B ra-stateless |
| 858 | and |
| 859 | .B slaac. |
Simon Kelley | c5ad4e7 | 2012-02-24 16:06:20 +0000 | [diff] [blame] | 860 | |
Simon Kelley | 7ea3d3f | 2014-04-25 22:04:05 +0100 | [diff] [blame] | 861 | .B ra-advrouter |
| 862 | enables a mode where router address(es) rather than prefix(es) are included in the advertisements. |
| 863 | This is described in RFC-3775 section 7.2 and is used in mobile IPv6. In this mode the interval option |
| 864 | is also included, as described in RFC-3775 section 7.3. |
| 865 | |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 866 | .TP |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 867 | .B \-G, --dhcp-host=[<hwaddr>][,id:<client_id>|*][,set:<tag>][,<ipaddr>][,<hostname>][,<lease_time>][,ignore] |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 868 | Specify per host parameters for the DHCP server. This allows a machine |
| 869 | with a particular hardware address to be always allocated the same |
| 870 | hostname, IP address and lease time. A hostname specified like this |
| 871 | overrides any supplied by the DHCP client on the machine. It is also |
Simon Kelley | c72daea | 2012-01-05 21:33:27 +0000 | [diff] [blame] | 872 | allowable to omit the hardware address and include the hostname, in |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 873 | which case the IP address and lease times will apply to any machine |
| 874 | claiming that name. For example |
| 875 | .B --dhcp-host=00:20:e0:3b:13:af,wap,infinite |
| 876 | tells dnsmasq to give |
Simon Kelley | cdeda28 | 2006-03-16 20:16:06 +0000 | [diff] [blame] | 877 | the machine with hardware address 00:20:e0:3b:13:af the name wap, and |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 878 | an infinite DHCP lease. |
| 879 | .B --dhcp-host=lap,192.168.0.199 |
| 880 | tells |
| 881 | dnsmasq to always allocate the machine lap the IP address |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 882 | 192.168.0.199. |
| 883 | |
| 884 | Addresses allocated like this are not constrained to be |
| 885 | in the range given by the --dhcp-range option, but they must be in |
| 886 | the same subnet as some valid dhcp-range. For |
| 887 | subnets which don't need a pool of dynamically allocated addresses, |
| 888 | use the "static" keyword in the dhcp-range declaration. |
| 889 | |
Simon Kelley | 89500e3 | 2013-09-20 16:29:20 +0100 | [diff] [blame] | 890 | It is allowed to use client identifiers (called client |
| 891 | DUID in IPv6-land rather than |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 892 | hardware addresses to identify hosts by prefixing with 'id:'. Thus: |
| 893 | .B --dhcp-host=id:01:02:03:04,..... |
| 894 | refers to the host with client identifier 01:02:03:04. It is also |
| 895 | allowed to specify the client ID as text, like this: |
Simon Kelley | a84fa1d | 2004-04-23 22:21:21 +0100 | [diff] [blame] | 896 | .B --dhcp-host=id:clientidastext,..... |
Simon Kelley | 9009d74 | 2008-11-14 20:04:27 +0000 | [diff] [blame] | 897 | |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 898 | A single |
| 899 | .B dhcp-host |
| 900 | may contain an IPv4 address or an IPv6 address, or both. IPv6 addresses must be bracketed by square brackets thus: |
| 901 | .B --dhcp-host=laptop,[1234::56] |
Simon Kelley | 3039310 | 2013-01-17 16:34:16 +0000 | [diff] [blame] | 902 | IPv6 addresses may contain only the host-identifier part: |
| 903 | .B --dhcp-host=laptop,[::56] |
Simon Kelley | 6f130de | 2013-04-15 14:47:14 +0100 | [diff] [blame] | 904 | in which case they act as wildcards in constructed dhcp ranges, with |
Simon Kelley | 3039310 | 2013-01-17 16:34:16 +0000 | [diff] [blame] | 905 | the appropriate network part inserted. |
Simon Kelley | 89500e3 | 2013-09-20 16:29:20 +0100 | [diff] [blame] | 906 | Note that in IPv6 DHCP, the hardware address may not be |
| 907 | available, though it normally is for direct-connected clients, or |
| 908 | clients using DHCP relays which support RFC 6939. |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 909 | |
Simon Kelley | 89500e3 | 2013-09-20 16:29:20 +0100 | [diff] [blame] | 910 | |
| 911 | For DHCPv4, the special option id:* means "ignore any client-id |
Simon Kelley | a84fa1d | 2004-04-23 22:21:21 +0100 | [diff] [blame] | 912 | and use MAC addresses only." This is useful when a client presents a client-id sometimes |
| 913 | but not others. |
Simon Kelley | 9009d74 | 2008-11-14 20:04:27 +0000 | [diff] [blame] | 914 | |
Simon Kelley | 1ab84e2 | 2004-01-29 16:48:35 +0000 | [diff] [blame] | 915 | If a name appears in /etc/hosts, the associated address can be |
| 916 | allocated to a DHCP lease, but only if a |
| 917 | .B --dhcp-host |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 918 | option specifying the name also exists. Only one hostname can be |
| 919 | given in a |
| 920 | .B dhcp-host |
| 921 | option, but aliases are possible by using CNAMEs. (See |
| 922 | .B --cname |
| 923 | ). |
| 924 | |
| 925 | The special keyword "ignore" |
Simon Kelley | 33820b7 | 2004-04-03 21:10:00 +0100 | [diff] [blame] | 926 | tells dnsmasq to never offer a DHCP lease to a machine. The machine |
| 927 | can be specified by hardware address, client ID or hostname, for |
| 928 | instance |
| 929 | .B --dhcp-host=00:20:e0:3b:13:af,ignore |
| 930 | This is |
| 931 | useful when there is another DHCP server on the network which should |
Simon Kelley | 9009d74 | 2008-11-14 20:04:27 +0000 | [diff] [blame] | 932 | be used by some machines. |
| 933 | |
Tomas Hozza | a66d36e | 2013-04-22 15:08:07 +0100 | [diff] [blame] | 934 | The set:<tag> construct sets the tag |
Simon Kelley | 9009d74 | 2008-11-14 20:04:27 +0000 | [diff] [blame] | 935 | whenever this dhcp-host directive is in use. This can be used to |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 936 | selectively send DHCP options just for this host. More than one tag |
| 937 | can be set in a dhcp-host directive (but not in other places where |
| 938 | "set:<tag>" is allowed). When a host matches any |
Simon Kelley | 5aabfc7 | 2007-08-29 11:24:47 +0100 | [diff] [blame] | 939 | dhcp-host directive (or one implied by /etc/ethers) then the special |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 940 | tag "known" is set. This allows dnsmasq to be configured to |
Simon Kelley | 5aabfc7 | 2007-08-29 11:24:47 +0100 | [diff] [blame] | 941 | ignore requests from unknown machines using |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 942 | .B --dhcp-ignore=tag:!known |
Simon Kelley | 0a85254 | 2005-03-23 20:28:59 +0000 | [diff] [blame] | 943 | Ethernet addresses (but not client-ids) may have |
| 944 | wildcard bytes, so for example |
| 945 | .B --dhcp-host=00:20:e0:3b:13:*,ignore |
Simon Kelley | cdeda28 | 2006-03-16 20:16:06 +0000 | [diff] [blame] | 946 | will cause dnsmasq to ignore a range of hardware addresses. Note that |
Simon Kelley | 0a85254 | 2005-03-23 20:28:59 +0000 | [diff] [blame] | 947 | the "*" will need to be escaped or quoted on a command line, but not |
Simon Kelley | 9009d74 | 2008-11-14 20:04:27 +0000 | [diff] [blame] | 948 | in the configuration file. |
| 949 | |
| 950 | Hardware addresses normally match any |
Simon Kelley | cdeda28 | 2006-03-16 20:16:06 +0000 | [diff] [blame] | 951 | network (ARP) type, but it is possible to restrict them to a single |
| 952 | ARP type by preceding them with the ARP-type (in HEX) and "-". so |
| 953 | .B --dhcp-host=06-00:20:e0:3b:13:af,1.2.3.4 |
| 954 | will only match a |
| 955 | Token-Ring hardware address, since the ARP-address type for token ring |
Simon Kelley | 9009d74 | 2008-11-14 20:04:27 +0000 | [diff] [blame] | 956 | is 6. |
| 957 | |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 958 | As a special case, in DHCPv4, it is possible to include more than one |
Simon Kelley | 73a08a2 | 2009-02-05 20:28:08 +0000 | [diff] [blame] | 959 | hardware address. eg: |
| 960 | .B --dhcp-host=11:22:33:44:55:66,12:34:56:78:90:12,192.168.0.2 |
| 961 | This allows an IP address to be associated with |
Simon Kelley | 9009d74 | 2008-11-14 20:04:27 +0000 | [diff] [blame] | 962 | multiple hardware addresses, and gives dnsmasq permission to abandon a |
| 963 | DHCP lease to one of the hardware addresses when another one asks for |
| 964 | a lease. Beware that this is a dangerous thing to do, it will only |
| 965 | work reliably if only one of the hardware addresses is active at any |
Simon Kelley | 73a08a2 | 2009-02-05 20:28:08 +0000 | [diff] [blame] | 966 | time and there is no way for dnsmasq to enforce this. It is, for instance, |
| 967 | useful to allocate a stable IP address to a laptop which |
Simon Kelley | 9009d74 | 2008-11-14 20:04:27 +0000 | [diff] [blame] | 968 | has both wired and wireless interfaces. |
Simon Kelley | 5aabfc7 | 2007-08-29 11:24:47 +0100 | [diff] [blame] | 969 | .TP |
Simon Kelley | 28866e9 | 2011-02-14 20:19:14 +0000 | [diff] [blame] | 970 | .B --dhcp-hostsfile=<path> |
| 971 | Read DHCP host information from the specified file. If a directory |
| 972 | is given, then read all the files contained in that directory. The file contains |
Simon Kelley | 5aabfc7 | 2007-08-29 11:24:47 +0100 | [diff] [blame] | 973 | information about one host per line. The format of a line is the same |
| 974 | as text to the right of '=' in --dhcp-host. The advantage of storing DHCP host information |
| 975 | in this file is that it can be changed without re-starting dnsmasq: |
| 976 | the file will be re-read when dnsmasq receives SIGHUP. |
Simon Kelley | 824af85 | 2008-02-12 20:43:05 +0000 | [diff] [blame] | 977 | .TP |
Simon Kelley | 28866e9 | 2011-02-14 20:19:14 +0000 | [diff] [blame] | 978 | .B --dhcp-optsfile=<path> |
| 979 | Read DHCP option information from the specified file. If a directory |
| 980 | is given, then read all the files contained in that directory. The advantage of |
Simon Kelley | 824af85 | 2008-02-12 20:43:05 +0000 | [diff] [blame] | 981 | using this option is the same as for --dhcp-hostsfile: the |
Simon Kelley | 1f15b81 | 2009-10-13 17:49:32 +0100 | [diff] [blame] | 982 | dhcp-optsfile will be re-read when dnsmasq receives SIGHUP. Note that |
| 983 | it is possible to encode the information in a |
Simon Kelley | 5f4dc5c | 2015-01-20 20:51:02 +0000 | [diff] [blame] | 984 | .TP |
| 985 | .B --dhcp-hostsdir=<path> |
Simon Kelley | 3d04f46 | 2015-01-31 21:59:13 +0000 | [diff] [blame] | 986 | This is equivalent to dhcp-hostsfile, except for the following. The path MUST be a |
Simon Kelley | 5f4dc5c | 2015-01-20 20:51:02 +0000 | [diff] [blame] | 987 | directory, and not an individual file. Changed or new files within |
| 988 | the directory are read automatically, without the need to send SIGHUP. |
| 989 | If a file is deleted for changed after it has been read by dnsmasq, then the |
| 990 | host record it contained will remain until dnsmasq recieves a SIGHUP, or |
| 991 | is restarted; ie host records are only added dynamically. |
Simon Kelley | 3d04f46 | 2015-01-31 21:59:13 +0000 | [diff] [blame] | 992 | .B --dhcp-optsdir=<path> |
| 993 | This is equivalent to dhcp-optsfile, with the differences noted for --dhcp-hostsdir. |
Simon Kelley | 5f4dc5c | 2015-01-20 20:51:02 +0000 | [diff] [blame] | 994 | .TP |
Simon Kelley | 1f15b81 | 2009-10-13 17:49:32 +0100 | [diff] [blame] | 995 | .B --dhcp-boot |
| 996 | flag as DHCP options, using the options names bootfile-name, |
| 997 | server-ip-address and tftp-server. This allows these to be included |
| 998 | in a dhcp-optsfile. |
Simon Kelley | 44a2a31 | 2004-03-10 20:04:35 +0000 | [diff] [blame] | 999 | .TP |
| 1000 | .B \-Z, --read-ethers |
| 1001 | Read /etc/ethers for information about hosts for the DHCP server. The |
| 1002 | format of /etc/ethers is a hardware address, followed by either a |
| 1003 | hostname or dotted-quad IP address. When read by dnsmasq these lines |
| 1004 | have exactly the same effect as |
| 1005 | .B --dhcp-host |
Simon Kelley | 5aabfc7 | 2007-08-29 11:24:47 +0100 | [diff] [blame] | 1006 | options containing the same information. /etc/ethers is re-read when |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1007 | dnsmasq receives SIGHUP. IPv6 addresses are NOT read from /etc/ethers. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1008 | .TP |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1009 | .B \-O, --dhcp-option=[tag:<tag>,[tag:<tag>,]][encap:<opt>,][vi-encap:<enterprise>,][vendor:[<vendor-class>],][<opt>|option:<opt-name>|option6:<opt>|option6:<opt-name>],[<value>[,<value>]] |
Simon Kelley | b8187c8 | 2005-11-26 21:46:27 +0000 | [diff] [blame] | 1010 | Specify different or extra options to DHCP clients. By default, |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1011 | dnsmasq sends some standard options to DHCP clients, the netmask and |
| 1012 | broadcast address are set to the same as the host running dnsmasq, and |
| 1013 | the DNS server and default route are set to the address of the machine |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1014 | running dnsmasq. (Equivalent rules apply for IPv6.) If the domain name option has been set, that is sent. |
Simon Kelley | f2621c7 | 2007-04-29 19:47:21 +0100 | [diff] [blame] | 1015 | This configuration allows these defaults to be overridden, |
| 1016 | or other options specified. The option, to be sent may be given as a |
| 1017 | decimal number or as "option:<option-name>" The option numbers are |
| 1018 | specified in RFC2132 and subsequent RFCs. The set of option-names |
| 1019 | known by dnsmasq can be discovered by running "dnsmasq --help dhcp". |
| 1020 | For example, to set the default route option to |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1021 | 192.168.4.4, do |
Simon Kelley | f2621c7 | 2007-04-29 19:47:21 +0100 | [diff] [blame] | 1022 | .B --dhcp-option=3,192.168.4.4 |
| 1023 | or |
| 1024 | .B --dhcp-option = option:router, 192.168.4.4 |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1025 | and to set the time-server address to 192.168.0.4, do |
Simon Kelley | f2621c7 | 2007-04-29 19:47:21 +0100 | [diff] [blame] | 1026 | .B --dhcp-option = 42,192.168.0.4 |
| 1027 | or |
| 1028 | .B --dhcp-option = option:ntp-server, 192.168.0.4 |
Simon Kelley | c3a0408 | 2014-01-11 22:18:19 +0000 | [diff] [blame] | 1029 | The special address 0.0.0.0 is taken to mean "the address of the |
| 1030 | machine running dnsmasq". |
| 1031 | |
| 1032 | Data types allowed are comma separated |
| 1033 | dotted-quad IPv4 addresses, []-wrapped IPv6 addresses, a decimal number, colon-separated hex digits |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1034 | and a text string. If the optional tags are given then |
| 1035 | this option is only sent when all the tags are matched. |
Simon Kelley | 91dccd0 | 2005-03-31 17:48:32 +0100 | [diff] [blame] | 1036 | |
Simon Kelley | cdeda28 | 2006-03-16 20:16:06 +0000 | [diff] [blame] | 1037 | Special processing is done on a text argument for option 119, to |
Simon Kelley | 832af0b | 2007-01-21 20:01:28 +0000 | [diff] [blame] | 1038 | conform with RFC 3397. Text or dotted-quad IP addresses as arguments |
| 1039 | to option 120 are handled as per RFC 3361. Dotted-quad IP addresses |
| 1040 | which are followed by a slash and then a netmask size are encoded as |
| 1041 | described in RFC 3442. |
Simon Kelley | cdeda28 | 2006-03-16 20:16:06 +0000 | [diff] [blame] | 1042 | |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1043 | IPv6 options are specified using the |
| 1044 | .B option6: |
| 1045 | keyword, followed by the option number or option name. The IPv6 option |
| 1046 | name space is disjoint from the IPv4 option name space. IPv6 addresses |
| 1047 | in options must be bracketed with square brackets, eg. |
| 1048 | .B --dhcp-option=option6:ntp-server,[1234::56] |
Simon Kelley | c3a0408 | 2014-01-11 22:18:19 +0000 | [diff] [blame] | 1049 | For IPv6, [::] means "the global address of |
| 1050 | the machine running dnsmasq", whilst [fd00::] is replaced with the |
| 1051 | ULA, if it exists, and [fe80::] with the link-local address. |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1052 | |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1053 | Be careful: no checking is done that the correct type of data for the |
Simon Kelley | 26128d2 | 2004-11-14 16:43:54 +0000 | [diff] [blame] | 1054 | option number is sent, it is quite possible to |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1055 | persuade dnsmasq to generate illegal DHCP packets with injudicious use |
Simon Kelley | 91dccd0 | 2005-03-31 17:48:32 +0100 | [diff] [blame] | 1056 | of this flag. When the value is a decimal number, dnsmasq must determine how |
| 1057 | large the data item is. It does this by examining the option number and/or the |
Simon Kelley | b8187c8 | 2005-11-26 21:46:27 +0000 | [diff] [blame] | 1058 | value, but can be overridden by appending a single letter flag as follows: |
Simon Kelley | 91dccd0 | 2005-03-31 17:48:32 +0100 | [diff] [blame] | 1059 | b = one byte, s = two bytes, i = four bytes. This is mainly useful with |
Simon Kelley | 3d8df26 | 2005-08-29 12:19:27 +0100 | [diff] [blame] | 1060 | encapsulated vendor class options (see below) where dnsmasq cannot |
| 1061 | determine data size from the option number. Option data which |
| 1062 | consists solely of periods and digits will be interpreted by dnsmasq |
| 1063 | as an IP address, and inserted into an option as such. To force a |
| 1064 | literal string, use quotes. For instance when using option 66 to send |
| 1065 | a literal IP address as TFTP server name, it is necessary to do |
| 1066 | .B --dhcp-option=66,"1.2.3.4" |
Simon Kelley | 91dccd0 | 2005-03-31 17:48:32 +0100 | [diff] [blame] | 1067 | |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1068 | Encapsulated Vendor-class options may also be specified (IPv4 only) using |
Simon Kelley | 91dccd0 | 2005-03-31 17:48:32 +0100 | [diff] [blame] | 1069 | --dhcp-option: for instance |
Simon Kelley | 1b7ecd1 | 2007-02-05 14:57:57 +0000 | [diff] [blame] | 1070 | .B --dhcp-option=vendor:PXEClient,1,0.0.0.0 |
| 1071 | sends the encapsulated vendor |
| 1072 | class-specific option "mftp-address=0.0.0.0" to any client whose |
| 1073 | vendor-class matches "PXEClient". The vendor-class matching is |
Simon Kelley | 6b01084 | 2007-02-12 20:32:07 +0000 | [diff] [blame] | 1074 | substring based (see --dhcp-vendorclass for details). If a |
| 1075 | vendor-class option (number 60) is sent by dnsmasq, then that is used |
| 1076 | for selecting encapsulated options in preference to any sent by the |
| 1077 | client. It is |
Simon Kelley | 1b7ecd1 | 2007-02-05 14:57:57 +0000 | [diff] [blame] | 1078 | possible to omit the vendorclass completely; |
| 1079 | .B --dhcp-option=vendor:,1,0.0.0.0 |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1080 | in which case the encapsulated option is always sent. |
Simon Kelley | 73a08a2 | 2009-02-05 20:28:08 +0000 | [diff] [blame] | 1081 | |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1082 | Options may be encapsulated (IPv4 only) within other options: for instance |
Simon Kelley | 73a08a2 | 2009-02-05 20:28:08 +0000 | [diff] [blame] | 1083 | .B --dhcp-option=encap:175, 190, "iscsi-client0" |
| 1084 | will send option 175, within which is the option 190. If multiple |
| 1085 | options are given which are encapsulated with the same option number |
| 1086 | then they will be correctly combined into one encapsulated option. |
| 1087 | encap: and vendor: are may not both be set in the same dhcp-option. |
| 1088 | |
Simon Kelley | 316e273 | 2010-01-22 20:16:09 +0000 | [diff] [blame] | 1089 | The final variant on encapsulated options is "Vendor-Identifying |
| 1090 | Vendor Options" as specified by RFC3925. These are denoted like this: |
| 1091 | .B --dhcp-option=vi-encap:2, 10, "text" |
| 1092 | The number in the vi-encap: section is the IANA enterprise number |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1093 | used to identify this option. This form of encapsulation is supported |
| 1094 | in IPv6. |
| 1095 | |
Simon Kelley | 1b7ecd1 | 2007-02-05 14:57:57 +0000 | [diff] [blame] | 1096 | The address 0.0.0.0 is not treated specially in |
Simon Kelley | 73a08a2 | 2009-02-05 20:28:08 +0000 | [diff] [blame] | 1097 | encapsulated options. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1098 | .TP |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1099 | .B --dhcp-option-force=[tag:<tag>,[tag:<tag>,]][encap:<opt>,][vi-encap:<enterprise>,][vendor:[<vendor-class>],]<opt>,[<value>[,<value>]] |
Simon Kelley | 6b01084 | 2007-02-12 20:32:07 +0000 | [diff] [blame] | 1100 | This works in exactly the same way as |
Simon Kelley | f2621c7 | 2007-04-29 19:47:21 +0100 | [diff] [blame] | 1101 | .B --dhcp-option |
| 1102 | except that the option will always be sent, even if the client does |
Simon Kelley | 6b01084 | 2007-02-12 20:32:07 +0000 | [diff] [blame] | 1103 | not ask for it in the parameter request list. This is sometimes |
| 1104 | needed, for example when sending options to PXELinux. |
| 1105 | .TP |
Simon Kelley | 824af85 | 2008-02-12 20:43:05 +0000 | [diff] [blame] | 1106 | .B --dhcp-no-override |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1107 | (IPv4 only) Disable re-use of the DHCP servername and filename fields as extra |
Simon Kelley | 824af85 | 2008-02-12 20:43:05 +0000 | [diff] [blame] | 1108 | option space. If it can, dnsmasq moves the boot server and filename |
| 1109 | information (from dhcp-boot) out of their dedicated fields into |
| 1110 | DHCP options. This make extra space available in the DHCP packet for |
| 1111 | options but can, rarely, confuse old or broken clients. This flag |
| 1112 | forces "simple and safe" behaviour to avoid problems in such a case. |
| 1113 | .TP |
Simon Kelley | ff7eea2 | 2013-09-04 18:01:38 +0100 | [diff] [blame] | 1114 | .B --dhcp-relay=<local address>,<server address>[,<interface] |
| 1115 | Configure dnsmasq to do DHCP relay. The local address is an address |
| 1116 | allocated to an interface on the host running dnsmasq. All DHCP |
| 1117 | requests arriving on that interface will we relayed to a remote DHCP |
| 1118 | server at the server address. It is possible to relay from a single local |
| 1119 | address to multiple remote servers by using multiple dhcp-relay |
| 1120 | configs with the same local address and different server |
| 1121 | addresses. A server address must be an IP literal address, not a |
| 1122 | domain name. In the case of DHCPv6, the server address may be the |
| 1123 | ALL_SERVERS multicast address, ff05::1:3. In this case the interface |
| 1124 | must be given, not be wildcard, and is used to direct the multicast to the |
| 1125 | correct interface to reach the DHCP server. |
| 1126 | |
| 1127 | Access control for DHCP clients has the same rules as for the DHCP |
| 1128 | server, see --interface, --except-interface, etc. The optional |
| 1129 | interface name in the dhcp-relay config has a different function: it |
| 1130 | controls on which interface DHCP replies from the server will be |
| 1131 | accepted. This is intended for configurations which have three |
| 1132 | interfaces: one being relayed from, a second connecting the DHCP |
| 1133 | server, and a third untrusted network, typically the wider |
| 1134 | internet. It avoids the possibility of spoof replies arriving via this |
| 1135 | third interface. |
| 1136 | |
| 1137 | It is allowed to have dnsmasq act as a DHCP server on one set of |
| 1138 | interfaces and relay from a disjoint set of interfaces. Note that |
| 1139 | whilst it is quite possible to write configurations which appear to |
| 1140 | act as a server and a relay on the same interface, this is not |
| 1141 | supported: the relay function will take precedence. |
| 1142 | |
| 1143 | Both DHCPv4 and DHCPv6 relay is supported. It's not possible to relay |
| 1144 | DHCPv4 to a DHCPv6 server or vice-versa. |
| 1145 | .TP |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1146 | .B \-U, --dhcp-vendorclass=set:<tag>,[enterprise:<IANA-enterprise number>,]<vendor-class> |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1147 | Map from a vendor-class string to a tag. Most DHCP clients provide a |
Simon Kelley | a222641 | 2004-05-13 20:27:08 +0100 | [diff] [blame] | 1148 | "vendor class" which represents, in some sense, the type of host. This option |
Simon Kelley | f2621c7 | 2007-04-29 19:47:21 +0100 | [diff] [blame] | 1149 | maps vendor classes to tags, so that DHCP options may be selectively delivered |
Simon Kelley | a84fa1d | 2004-04-23 22:21:21 +0100 | [diff] [blame] | 1150 | to different classes of hosts. For example |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1151 | .B dhcp-vendorclass=set:printers,Hewlett-Packard JetDirect |
Simon Kelley | a84fa1d | 2004-04-23 22:21:21 +0100 | [diff] [blame] | 1152 | will allow options to be set only for HP printers like so: |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1153 | .B --dhcp-option=tag:printers,3,192.168.4.4 |
Simon Kelley | a222641 | 2004-05-13 20:27:08 +0100 | [diff] [blame] | 1154 | The vendor-class string is |
| 1155 | substring matched against the vendor-class supplied by the client, to |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1156 | allow fuzzy matching. The set: prefix is optional but allowed for |
| 1157 | consistency. |
| 1158 | |
| 1159 | Note that in IPv6 only, vendorclasses are namespaced with an |
| 1160 | IANA-allocated enterprise number. This is given with enterprise: |
| 1161 | keyword and specifies that only vendorclasses matching the specified |
| 1162 | number should be searched. |
Simon Kelley | a222641 | 2004-05-13 20:27:08 +0100 | [diff] [blame] | 1163 | .TP |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1164 | .B \-j, --dhcp-userclass=set:<tag>,<user-class> |
| 1165 | Map from a user-class string to a tag (with substring |
Simon Kelley | a222641 | 2004-05-13 20:27:08 +0100 | [diff] [blame] | 1166 | matching, like vendor classes). Most DHCP clients provide a |
| 1167 | "user class" which is configurable. This option |
Simon Kelley | f2621c7 | 2007-04-29 19:47:21 +0100 | [diff] [blame] | 1168 | maps user classes to tags, so that DHCP options may be selectively delivered |
Simon Kelley | a222641 | 2004-05-13 20:27:08 +0100 | [diff] [blame] | 1169 | to different classes of hosts. It is possible, for instance to use |
| 1170 | this to set a different printer server for hosts in the class |
| 1171 | "accounts" than for hosts in the class "engineering". |
Simon Kelley | a84fa1d | 2004-04-23 22:21:21 +0100 | [diff] [blame] | 1172 | .TP |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1173 | .B \-4, --dhcp-mac=set:<tag>,<MAC address> |
Simon Kelley | 89500e3 | 2013-09-20 16:29:20 +0100 | [diff] [blame] | 1174 | Map from a MAC address to a tag. The MAC address may include |
Simon Kelley | cdeda28 | 2006-03-16 20:16:06 +0000 | [diff] [blame] | 1175 | wildcards. For example |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1176 | .B --dhcp-mac=set:3com,01:34:23:*:*:* |
Simon Kelley | cdeda28 | 2006-03-16 20:16:06 +0000 | [diff] [blame] | 1177 | will set the tag "3com" for any host whose MAC address matches the pattern. |
| 1178 | .TP |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1179 | .B --dhcp-circuitid=set:<tag>,<circuit-id>, --dhcp-remoteid=set:<tag>,<remote-id> |
| 1180 | Map from RFC3046 relay agent options to tags. This data may |
Simon Kelley | f2621c7 | 2007-04-29 19:47:21 +0100 | [diff] [blame] | 1181 | be provided by DHCP relay agents. The circuit-id or remote-id is |
| 1182 | normally given as colon-separated hex, but is also allowed to be a |
| 1183 | simple string. If an exact match is achieved between the circuit or |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1184 | agent ID and one provided by a relay agent, the tag is set. |
| 1185 | |
| 1186 | .B dhcp-remoteid |
| 1187 | (but not dhcp-circuitid) is supported in IPv6. |
Simon Kelley | f2621c7 | 2007-04-29 19:47:21 +0100 | [diff] [blame] | 1188 | .TP |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1189 | .B --dhcp-subscrid=set:<tag>,<subscriber-id> |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1190 | (IPv4 and IPv6) Map from RFC3993 subscriber-id relay agent options to tags. |
Simon Kelley | 824af85 | 2008-02-12 20:43:05 +0000 | [diff] [blame] | 1191 | .TP |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1192 | .B --dhcp-proxy[=<ip addr>]...... |
Simon Kelley | 0793380 | 2012-02-14 20:55:25 +0000 | [diff] [blame] | 1193 | (IPv4 only) A normal DHCP relay agent is only used to forward the initial parts of |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1194 | a DHCP interaction to the DHCP server. Once a client is configured, it |
| 1195 | communicates directly with the server. This is undesirable if the |
Tomas Hozza | a66d36e | 2013-04-22 15:08:07 +0100 | [diff] [blame] | 1196 | relay agent is adding extra information to the DHCP packets, such as |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1197 | that used by |
| 1198 | .B dhcp-circuitid |
| 1199 | and |
| 1200 | .B dhcp-remoteid. |
| 1201 | A full relay implementation can use the RFC 5107 serverid-override |
| 1202 | option to force the DHCP server to use the relay as a full proxy, with all |
| 1203 | packets passing through it. This flag provides an alternative method |
| 1204 | of doing the same thing, for relays which don't support RFC |
| 1205 | 5107. Given alone, it manipulates the server-id for all interactions |
| 1206 | via relays. If a list of IP addresses is given, only interactions via |
| 1207 | relays at those addresses are affected. |
| 1208 | .TP |
| 1209 | .B --dhcp-match=set:<tag>,<option number>|option:<option name>|vi-encap:<enterprise>[,<value>] |
| 1210 | Without a value, set the tag if the client sends a DHCP |
Simon Kelley | 73a08a2 | 2009-02-05 20:28:08 +0000 | [diff] [blame] | 1211 | option of the given number or name. When a value is given, set the tag only if |
| 1212 | the option is sent and matches the value. The value may be of the form |
Tomas Hozza | a66d36e | 2013-04-22 15:08:07 +0100 | [diff] [blame] | 1213 | "01:ff:*:02" in which case the value must match (apart from wildcards) |
Simon Kelley | 73a08a2 | 2009-02-05 20:28:08 +0000 | [diff] [blame] | 1214 | but the option sent may have unmatched data past the end of the |
| 1215 | value. The value may also be of the same form as in |
| 1216 | .B dhcp-option |
| 1217 | in which case the option sent is treated as an array, and one element |
| 1218 | must match, so |
| 1219 | |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1220 | --dhcp-match=set:efi-ia32,option:client-arch,6 |
Simon Kelley | 73a08a2 | 2009-02-05 20:28:08 +0000 | [diff] [blame] | 1221 | |
| 1222 | will set the tag "efi-ia32" if the the number 6 appears in the list of |
| 1223 | architectures sent by the client in option 93. (See RFC 4578 for |
Simon Kelley | 316e273 | 2010-01-22 20:16:09 +0000 | [diff] [blame] | 1224 | details.) If the value is a string, substring matching is used. |
| 1225 | |
Tomas Hozza | a66d36e | 2013-04-22 15:08:07 +0100 | [diff] [blame] | 1226 | The special form with vi-encap:<enterprise number> matches against |
Simon Kelley | 316e273 | 2010-01-22 20:16:09 +0000 | [diff] [blame] | 1227 | vendor-identifying vendor classes for the specified enterprise. Please |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1228 | see RFC 3925 for more details of these rare and interesting beasts. |
Simon Kelley | f2621c7 | 2007-04-29 19:47:21 +0100 | [diff] [blame] | 1229 | .TP |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1230 | .B --tag-if=set:<tag>[,set:<tag>[,tag:<tag>[,tag:<tag>]]] |
| 1231 | Perform boolean operations on tags. Any tag appearing as set:<tag> is set if |
| 1232 | all the tags which appear as tag:<tag> are set, (or unset when tag:!<tag> is used) |
| 1233 | If no tag:<tag> appears set:<tag> tags are set unconditionally. |
| 1234 | Any number of set: and tag: forms may appear, in any order. |
| 1235 | Tag-if lines ares executed in order, so if the tag in tag:<tag> is a |
| 1236 | tag set by another |
| 1237 | .B tag-if, |
| 1238 | the line which sets the tag must precede the one which tests it. |
| 1239 | .TP |
| 1240 | .B \-J, --dhcp-ignore=tag:<tag>[,tag:<tag>] |
| 1241 | When all the given tags appear in the tag set ignore the host and do |
Simon Kelley | 26128d2 | 2004-11-14 16:43:54 +0000 | [diff] [blame] | 1242 | not allocate it a DHCP lease. |
| 1243 | .TP |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1244 | .B --dhcp-ignore-names[=tag:<tag>[,tag:<tag>]] |
| 1245 | When all the given tags appear in the tag set, ignore any hostname |
Simon Kelley | 9e03894 | 2008-05-30 20:06:34 +0100 | [diff] [blame] | 1246 | provided by the host. Note that, unlike dhcp-ignore, it is permissible |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1247 | to supply no tags, in which case DHCP-client supplied hostnames |
Simon Kelley | 832af0b | 2007-01-21 20:01:28 +0000 | [diff] [blame] | 1248 | are always ignored, and DHCP hosts are added to the DNS using only |
| 1249 | dhcp-host configuration in dnsmasq and the contents of /etc/hosts and |
| 1250 | /etc/ethers. |
| 1251 | .TP |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1252 | .B --dhcp-generate-names=tag:<tag>[,tag:<tag>] |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1253 | (IPv4 only) Generate a name for DHCP clients which do not otherwise have one, |
Tomas Hozza | a66d36e | 2013-04-22 15:08:07 +0100 | [diff] [blame] | 1254 | using the MAC address expressed in hex, separated by dashes. Note that |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1255 | if a host provides a name, it will be used by preference to this, |
| 1256 | unless |
| 1257 | .B --dhcp-ignore-names |
| 1258 | is set. |
| 1259 | .TP |
| 1260 | .B --dhcp-broadcast[=tag:<tag>[,tag:<tag>]] |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1261 | (IPv4 only) When all the given tags appear in the tag set, always use broadcast to |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1262 | communicate with the host when it is unconfigured. It is permissible |
| 1263 | to supply no tags, in which case this is unconditional. Most DHCP clients which |
Simon Kelley | 824af85 | 2008-02-12 20:43:05 +0000 | [diff] [blame] | 1264 | need broadcast replies set a flag in their requests so that this |
| 1265 | happens automatically, some old BOOTP clients do not. |
| 1266 | .TP |
Simon Kelley | 7de060b | 2011-08-26 17:24:52 +0100 | [diff] [blame] | 1267 | .B \-M, --dhcp-boot=[tag:<tag>,]<filename>,[<servername>[,<server address>|<tftp_servername>]] |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1268 | (IPv4 only) Set BOOTP options to be returned by the DHCP server. Server name and |
Simon Kelley | 832af0b | 2007-01-21 20:01:28 +0000 | [diff] [blame] | 1269 | address are optional: if not provided, the name is left empty, and the |
| 1270 | address set to the address of the machine running dnsmasq. If dnsmasq |
| 1271 | is providing a TFTP service (see |
| 1272 | .B --enable-tftp |
| 1273 | ) then only the filename is required here to enable network booting. |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1274 | If the optional tag(s) are given, |
| 1275 | they must match for this configuration to be sent. |
Simon Kelley | 7de060b | 2011-08-26 17:24:52 +0100 | [diff] [blame] | 1276 | Instead of an IP address, the TFTP server address can be given as a domain |
| 1277 | name which is looked up in /etc/hosts. This name can be associated in |
| 1278 | /etc/hosts with multiple IP addresses, which are used round-robin. |
| 1279 | This facility can be used to load balance the tftp load among a set of servers. |
| 1280 | .TP |
| 1281 | .B --dhcp-sequential-ip |
| 1282 | Dnsmasq is designed to choose IP addresses for DHCP clients using a |
| 1283 | hash of the client's MAC address. This normally allows a client's |
| 1284 | address to remain stable long-term, even if the client sometimes allows its DHCP |
| 1285 | lease to expire. In this default mode IP addresses are distributed |
| 1286 | pseudo-randomly over the entire available address range. There are |
| 1287 | sometimes circumstances (typically server deployment) where it is more |
| 1288 | convenient to have IP |
| 1289 | addresses allocated sequentially, starting from the lowest available |
| 1290 | address, and setting this flag enables this mode. Note that in the |
| 1291 | sequential mode, clients which allow a lease to expire are much more |
| 1292 | likely to move IP address; for this reason it should not be generally used. |
Simon Kelley | 7622fc0 | 2009-06-04 20:32:05 +0100 | [diff] [blame] | 1293 | .TP |
Simon Kelley | 751d6f4 | 2012-02-10 15:24:51 +0000 | [diff] [blame] | 1294 | .B --pxe-service=[tag:<tag>,]<CSA>,<menu text>[,<basename>|<bootservicetype>][,<server address>|<server_name>] |
Simon Kelley | 7622fc0 | 2009-06-04 20:32:05 +0100 | [diff] [blame] | 1295 | Most uses of PXE boot-ROMS simply allow the PXE |
| 1296 | system to obtain an IP address and then download the file specified by |
| 1297 | .B dhcp-boot |
| 1298 | and execute it. However the PXE system is capable of more complex |
| 1299 | functions when supported by a suitable DHCP server. |
| 1300 | |
| 1301 | This specifies a boot option which may appear in a PXE boot menu. <CSA> is |
| 1302 | client system type, only services of the correct type will appear in a |
| 1303 | menu. The known types are x86PC, PC98, IA64_EFI, Alpha, Arc_x86, |
| 1304 | Intel_Lean_Client, IA32_EFI, BC_EFI, Xscale_EFI and X86-64_EFI; an |
| 1305 | integer may be used for other types. The |
| 1306 | parameter after the menu text may be a file name, in which case dnsmasq acts as a |
| 1307 | boot server and directs the PXE client to download the file by TFTP, |
| 1308 | either from itself ( |
| 1309 | .B enable-tftp |
Simon Kelley | 751d6f4 | 2012-02-10 15:24:51 +0000 | [diff] [blame] | 1310 | must be set for this to work) or another TFTP server if the final server |
| 1311 | address/name is given. |
Simon Kelley | 7622fc0 | 2009-06-04 20:32:05 +0100 | [diff] [blame] | 1312 | Note that the "layer" |
| 1313 | suffix (normally ".0") is supplied by PXE, and should not be added to |
| 1314 | the basename. If an integer boot service type, rather than a basename |
| 1315 | is given, then the PXE client will search for a |
| 1316 | suitable boot service for that type on the network. This search may be done |
Simon Kelley | 751d6f4 | 2012-02-10 15:24:51 +0000 | [diff] [blame] | 1317 | by broadcast, or direct to a server if its IP address/name is provided. |
Simon Kelley | 316e273 | 2010-01-22 20:16:09 +0000 | [diff] [blame] | 1318 | If no boot service type or filename is provided (or a boot service type of 0 is specified) |
| 1319 | then the menu entry will abort the net boot procedure and |
Simon Kelley | 751d6f4 | 2012-02-10 15:24:51 +0000 | [diff] [blame] | 1320 | continue booting from local media. The server address can be given as a domain |
| 1321 | name which is looked up in /etc/hosts. This name can be associated in |
| 1322 | /etc/hosts with multiple IP addresses, which are used round-robin. |
Simon Kelley | 7622fc0 | 2009-06-04 20:32:05 +0100 | [diff] [blame] | 1323 | .TP |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1324 | .B --pxe-prompt=[tag:<tag>,]<prompt>[,<timeout>] |
Simon Kelley | 7622fc0 | 2009-06-04 20:32:05 +0100 | [diff] [blame] | 1325 | Setting this provides a prompt to be displayed after PXE boot. If the |
| 1326 | timeout is given then after the |
| 1327 | timeout has elapsed with no keyboard input, the first available menu |
| 1328 | option will be automatically executed. If the timeout is zero then the first available menu |
| 1329 | item will be executed immediately. If |
| 1330 | .B pxe-prompt |
Tomas Hozza | a66d36e | 2013-04-22 15:08:07 +0100 | [diff] [blame] | 1331 | is omitted the system will wait for user input if there are multiple |
Simon Kelley | 7622fc0 | 2009-06-04 20:32:05 +0100 | [diff] [blame] | 1332 | items in the menu, but boot immediately if |
| 1333 | there is only one. See |
| 1334 | .B pxe-service |
| 1335 | for details of menu items. |
| 1336 | |
| 1337 | Dnsmasq supports PXE "proxy-DHCP", in this case another DHCP server on |
| 1338 | the network is responsible for allocating IP addresses, and dnsmasq |
| 1339 | simply provides the information given in |
| 1340 | .B pxe-prompt |
| 1341 | and |
| 1342 | .B pxe-service |
| 1343 | to allow netbooting. This mode is enabled using the |
| 1344 | .B proxy |
| 1345 | keyword in |
| 1346 | .B dhcp-range. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1347 | .TP |
Simon Kelley | 44a2a31 | 2004-03-10 20:04:35 +0000 | [diff] [blame] | 1348 | .B \-X, --dhcp-lease-max=<number> |
| 1349 | Limits dnsmasq to the specified maximum number of DHCP leases. The |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1350 | default is 1000. This limit is to prevent DoS attacks from hosts which |
Simon Kelley | 44a2a31 | 2004-03-10 20:04:35 +0000 | [diff] [blame] | 1351 | create thousands of leases and use lots of memory in the dnsmasq |
| 1352 | process. |
| 1353 | .TP |
Simon Kelley | fd9fa48 | 2004-10-21 20:24:00 +0100 | [diff] [blame] | 1354 | .B \-K, --dhcp-authoritative |
Simon Kelley | 095f625 | 2013-01-30 11:31:02 +0000 | [diff] [blame] | 1355 | Should be set when dnsmasq is definitely the only DHCP server on a network. |
| 1356 | For DHCPv4, it changes the behaviour from strict RFC compliance so that DHCP requests on |
Simon Kelley | fd9fa48 | 2004-10-21 20:24:00 +0100 | [diff] [blame] | 1357 | unknown leases from unknown hosts are not ignored. This allows new hosts |
Simon Kelley | cdeda28 | 2006-03-16 20:16:06 +0000 | [diff] [blame] | 1358 | to get a lease without a tedious timeout under all circumstances. It also |
| 1359 | allows dnsmasq to rebuild its lease database without each client needing to |
Simon Kelley | 095f625 | 2013-01-30 11:31:02 +0000 | [diff] [blame] | 1360 | reacquire a lease, if the database is lost. For DHCPv6 it sets the |
| 1361 | priority in replies to 255 (the maximum) instead of 0 (the minimum). |
Simon Kelley | 9e03894 | 2008-05-30 20:06:34 +0100 | [diff] [blame] | 1362 | .TP |
| 1363 | .B --dhcp-alternate-port[=<server port>[,<client port>]] |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1364 | (IPv4 only) Change the ports used for DHCP from the default. If this option is |
Simon Kelley | 9e03894 | 2008-05-30 20:06:34 +0100 | [diff] [blame] | 1365 | given alone, without arguments, it changes the ports used for DHCP |
| 1366 | from 67 and 68 to 1067 and 1068. If a single argument is given, that |
| 1367 | port number is used for the server and the port number plus one used |
| 1368 | for the client. Finally, two port numbers allows arbitrary |
| 1369 | specification of both server and client ports for DHCP. |
Simon Kelley | fd9fa48 | 2004-10-21 20:24:00 +0100 | [diff] [blame] | 1370 | .TP |
Simon Kelley | 9009d74 | 2008-11-14 20:04:27 +0000 | [diff] [blame] | 1371 | .B \-3, --bootp-dynamic[=<network-id>[,<network-id>]] |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1372 | (IPv4 only) Enable dynamic allocation of IP addresses to BOOTP clients. Use this |
Simon Kelley | 3d8df26 | 2005-08-29 12:19:27 +0100 | [diff] [blame] | 1373 | with care, since each address allocated to a BOOTP client is leased |
| 1374 | forever, and therefore becomes permanently unavailable for re-use by |
Simon Kelley | 9009d74 | 2008-11-14 20:04:27 +0000 | [diff] [blame] | 1375 | other hosts. if this is given without tags, then it unconditionally |
| 1376 | enables dynamic allocation. With tags, only when the tags are all |
| 1377 | set. It may be repeated with different tag sets. |
Simon Kelley | 3d8df26 | 2005-08-29 12:19:27 +0100 | [diff] [blame] | 1378 | .TP |
Simon Kelley | 5e9e0ef | 2006-04-17 14:24:29 +0100 | [diff] [blame] | 1379 | .B \-5, --no-ping |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1380 | (IPv4 only) By default, the DHCP server will attempt to ensure that an address in |
Simon Kelley | 5e9e0ef | 2006-04-17 14:24:29 +0100 | [diff] [blame] | 1381 | not in use before allocating it to a host. It does this by sending an |
| 1382 | ICMP echo request (aka "ping") to the address in question. If it gets |
| 1383 | a reply, then the address must already be in use, and another is |
| 1384 | tried. This flag disables this check. Use with caution. |
| 1385 | .TP |
Simon Kelley | f2621c7 | 2007-04-29 19:47:21 +0100 | [diff] [blame] | 1386 | .B --log-dhcp |
| 1387 | Extra logging for DHCP: log all the options sent to DHCP clients and |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1388 | the tags used to determine them. |
Simon Kelley | f2621c7 | 2007-04-29 19:47:21 +0100 | [diff] [blame] | 1389 | .TP |
Kevin Darbyshire-Bryant | 8c0b73d | 2013-10-11 11:56:33 +0100 | [diff] [blame] | 1390 | .B --quiet-dhcp, --quiet-dhcp6, --quiet-ra |
| 1391 | Suppress logging of the routine operation of these protocols. Errors and |
| 1392 | problems will still be logged. --quiet-dhcp and quiet-dhcp6 are |
| 1393 | over-ridden by --log-dhcp. |
| 1394 | .TP |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1395 | .B \-l, --dhcp-leasefile=<path> |
Simon Kelley | 73a08a2 | 2009-02-05 20:28:08 +0000 | [diff] [blame] | 1396 | Use the specified file to store DHCP lease information. |
Simon Kelley | 208b65c | 2006-08-05 21:41:37 +0100 | [diff] [blame] | 1397 | .TP |
Simon Kelley | 8b37270 | 2012-03-09 17:45:10 +0000 | [diff] [blame] | 1398 | .B --dhcp-duid=<enterprise-id>,<uid> |
| 1399 | (IPv6 only) Specify the server persistent UID which the DHCPv6 server |
| 1400 | will use. This option is not normally required as dnsmasq creates a |
| 1401 | DUID automatically when it is first needed. When given, this option |
| 1402 | provides dnsmasq the data required to create a DUID-EN type DUID. Note |
| 1403 | that once set, the DUID is stored in the lease database, so to change between DUID-EN and |
| 1404 | automatically created DUIDs or vice-versa, the lease database must be |
| 1405 | re-intialised. The enterprise-id is assigned by IANA, and the uid is a |
| 1406 | string of hex octets unique to a particular device. |
| 1407 | .TP |
Simon Kelley | 7cebd20 | 2006-05-06 14:13:33 +0100 | [diff] [blame] | 1408 | .B \-6 --dhcp-script=<path> |
Simon Kelley | a953096 | 2012-03-20 22:07:35 +0000 | [diff] [blame] | 1409 | Whenever a new DHCP lease is created, or an old one destroyed, or a |
| 1410 | TFTP file transfer completes, the |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1411 | executable specified by this option is run. <path> |
| 1412 | must be an absolute pathname, no PATH search occurs. |
| 1413 | The arguments to the process |
Simon Kelley | 7cebd20 | 2006-05-06 14:13:33 +0100 | [diff] [blame] | 1414 | are "add", "old" or "del", the MAC |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1415 | address of the host (or DUID for IPv6) , the IP address, and the hostname, |
Simon Kelley | 7cebd20 | 2006-05-06 14:13:33 +0100 | [diff] [blame] | 1416 | if known. "add" means a lease has been created, "del" means it has |
| 1417 | been destroyed, "old" is a notification of an existing lease when |
Simon Kelley | 208b65c | 2006-08-05 21:41:37 +0100 | [diff] [blame] | 1418 | dnsmasq starts or a change to MAC address or hostname of an existing |
| 1419 | lease (also, lease length or expiry and client-id, if leasefile-ro is set). |
Simon Kelley | 9009d74 | 2008-11-14 20:04:27 +0000 | [diff] [blame] | 1420 | If the MAC address is from a network type other than ethernet, |
| 1421 | it will have the network type prepended, eg "06-01:23:45:67:89:ab" for |
| 1422 | token ring. The process is run as root (assuming that dnsmasq was originally run as |
Simon Kelley | 1697269 | 2006-10-16 20:04:18 +0100 | [diff] [blame] | 1423 | root) even if dnsmasq is configured to change UID to an unprivileged user. |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1424 | |
| 1425 | The environment is inherited from the invoker of dnsmasq, with some or |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1426 | all of the following variables added |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1427 | |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1428 | For both IPv4 and IPv6: |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1429 | |
| 1430 | DNSMASQ_DOMAIN if the fully-qualified domain name of the host is |
Simon Kelley | 28866e9 | 2011-02-14 20:19:14 +0000 | [diff] [blame] | 1431 | known, this is set to the domain part. (Note that the hostname passed |
| 1432 | to the script as an argument is never fully-qualified.) |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1433 | |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1434 | If the client provides a hostname, DNSMASQ_SUPPLIED_HOSTNAME |
| 1435 | |
| 1436 | If the client provides user-classes, DNSMASQ_USER_CLASS0..DNSMASQ_USER_CLASSn |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1437 | |
| 1438 | If dnsmasq was compiled with HAVE_BROKEN_RTC, then |
Simon Kelley | 208b65c | 2006-08-05 21:41:37 +0100 | [diff] [blame] | 1439 | the length of the lease (in seconds) is stored in |
Simon Kelley | 1697269 | 2006-10-16 20:04:18 +0100 | [diff] [blame] | 1440 | DNSMASQ_LEASE_LENGTH, otherwise the time of lease expiry is stored in |
Simon Kelley | 5aabfc7 | 2007-08-29 11:24:47 +0100 | [diff] [blame] | 1441 | DNSMASQ_LEASE_EXPIRES. The number of seconds until lease expiry is |
| 1442 | always stored in DNSMASQ_TIME_REMAINING. |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1443 | |
Simon Kelley | 5aabfc7 | 2007-08-29 11:24:47 +0100 | [diff] [blame] | 1444 | If a lease used to have a hostname, which is |
Simon Kelley | 1697269 | 2006-10-16 20:04:18 +0100 | [diff] [blame] | 1445 | removed, an "old" event is generated with the new state of the lease, |
| 1446 | ie no name, and the former name is provided in the environment |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1447 | variable DNSMASQ_OLD_HOSTNAME. |
| 1448 | |
| 1449 | DNSMASQ_INTERFACE stores the name of |
Simon Kelley | 9e03894 | 2008-05-30 20:06:34 +0100 | [diff] [blame] | 1450 | the interface on which the request arrived; this is not set for "old" |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1451 | actions when dnsmasq restarts. |
| 1452 | |
| 1453 | DNSMASQ_RELAY_ADDRESS is set if the client |
Simon Kelley | 316e273 | 2010-01-22 20:16:09 +0000 | [diff] [blame] | 1454 | used a DHCP relay to contact dnsmasq and the IP address of the relay |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1455 | is known. |
| 1456 | |
| 1457 | DNSMASQ_TAGS contains all the tags set during the |
Simon Kelley | 316e273 | 2010-01-22 20:16:09 +0000 | [diff] [blame] | 1458 | DHCP transaction, separated by spaces. |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1459 | |
Simon Kelley | e46164e | 2012-04-16 16:39:38 +0100 | [diff] [blame] | 1460 | DNSMASQ_LOG_DHCP is set if |
| 1461 | .B --log-dhcp |
| 1462 | is in effect. |
Simon Kelley | a953096 | 2012-03-20 22:07:35 +0000 | [diff] [blame] | 1463 | |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1464 | For IPv4 only: |
| 1465 | |
| 1466 | DNSMASQ_CLIENT_ID if the host provided a client-id. |
| 1467 | |
Simon Kelley | dd1721c | 2013-02-18 21:04:04 +0000 | [diff] [blame] | 1468 | DNSMASQ_CIRCUIT_ID, DNSMASQ_SUBSCRIBER_ID, DNSMASQ_REMOTE_ID if a |
| 1469 | DHCP relay-agent added any of these options. |
| 1470 | |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1471 | If the client provides vendor-class, DNSMASQ_VENDOR_CLASS. |
| 1472 | |
| 1473 | For IPv6 only: |
| 1474 | |
| 1475 | If the client provides vendor-class, DNSMASQ_VENDOR_CLASS_ID, |
| 1476 | containing the IANA enterprise id for the class, and |
| 1477 | DNSMASQ_VENDOR_CLASS0..DNSMASQ_VENDOR_CLASSn for the data. |
| 1478 | |
Simon Kelley | 57f460d | 2012-02-16 20:00:32 +0000 | [diff] [blame] | 1479 | DNSMASQ_SERVER_DUID containing the DUID of the server: this is the same for |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1480 | every call to the script. |
| 1481 | |
| 1482 | DNSMASQ_IAID containing the IAID for the lease. If the lease is a |
| 1483 | temporary allocation, this is prefixed to 'T'. |
| 1484 | |
Simon Kelley | 89500e3 | 2013-09-20 16:29:20 +0100 | [diff] [blame] | 1485 | DNSMASQ_MAC containing the MAC address of the client, if known. |
Simon Kelley | 1adadf5 | 2012-02-13 22:15:58 +0000 | [diff] [blame] | 1486 | |
| 1487 | Note that the supplied hostname, vendorclass and userclass data is |
| 1488 | only supplied for |
| 1489 | "add" actions or "old" actions when a host resumes an existing lease, |
| 1490 | since these data are not held in dnsmasq's lease |
| 1491 | database. |
| 1492 | |
Simon Kelley | a953096 | 2012-03-20 22:07:35 +0000 | [diff] [blame] | 1493 | |
| 1494 | |
Simon Kelley | 9e03894 | 2008-05-30 20:06:34 +0100 | [diff] [blame] | 1495 | All file descriptors are |
Simon Kelley | 7cebd20 | 2006-05-06 14:13:33 +0100 | [diff] [blame] | 1496 | closed except stdin, stdout and stderr which are open to /dev/null |
| 1497 | (except in debug mode). |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1498 | |
| 1499 | The script is not invoked concurrently: at most one instance |
| 1500 | of the script is ever running (dnsmasq waits for an instance of script to exit |
| 1501 | before running the next). Changes to the lease database are which |
| 1502 | require the script to be invoked are queued awaiting exit of a running instance. |
| 1503 | If this queueing allows multiple state changes occur to a single |
| 1504 | lease before the script can be run then |
| 1505 | earlier states are discarded and the current state of that lease is |
| 1506 | reflected when the script finally runs. |
| 1507 | |
| 1508 | At dnsmasq startup, the script will be invoked for |
Simon Kelley | 7cebd20 | 2006-05-06 14:13:33 +0100 | [diff] [blame] | 1509 | all existing leases as they are read from the lease file. Expired |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1510 | leases will be called with "del" and others with "old". When dnsmasq |
Simon Kelley | 5aabfc7 | 2007-08-29 11:24:47 +0100 | [diff] [blame] | 1511 | receives a HUP signal, the script will be invoked for existing leases |
Simon Kelley | 9e03894 | 2008-05-30 20:06:34 +0100 | [diff] [blame] | 1512 | with an "old " event. |
Simon Kelley | a953096 | 2012-03-20 22:07:35 +0000 | [diff] [blame] | 1513 | |
| 1514 | |
| 1515 | There are two further actions which may appear as the first argument |
| 1516 | to the script, "init" and "tftp". More may be added in the future, so |
| 1517 | scripts should be written to ignore unknown actions. "init" is |
Simon Kelley | e46164e | 2012-04-16 16:39:38 +0100 | [diff] [blame] | 1518 | described below in |
Simon Kelley | a953096 | 2012-03-20 22:07:35 +0000 | [diff] [blame] | 1519 | .B --leasefile-ro |
| 1520 | The "tftp" action is invoked when a TFTP file transfer completes: the |
| 1521 | arguments are the file size in bytes, the address to which the file |
| 1522 | was sent, and the complete pathname of the file. |
| 1523 | |
Simon Kelley | 9e03894 | 2008-05-30 20:06:34 +0100 | [diff] [blame] | 1524 | .TP |
Simon Kelley | 57f460d | 2012-02-16 20:00:32 +0000 | [diff] [blame] | 1525 | .B --dhcp-luascript=<path> |
| 1526 | Specify a script written in Lua, to be run when leases are created, |
| 1527 | destroyed or changed. To use this option, dnsmasq must be compiled |
| 1528 | with the correct support. The Lua interpreter is intialised once, when |
| 1529 | dnsmasq starts, so that global variables persist between lease |
| 1530 | events. The Lua code must define a |
| 1531 | .B lease |
| 1532 | function, and may provide |
| 1533 | .B init |
| 1534 | and |
| 1535 | .B shutdown |
| 1536 | functions, which are called, without arguments when dnsmasq starts up |
Simon Kelley | a953096 | 2012-03-20 22:07:35 +0000 | [diff] [blame] | 1537 | and terminates. It may also provide a |
| 1538 | .B tftp |
| 1539 | function. |
Simon Kelley | 57f460d | 2012-02-16 20:00:32 +0000 | [diff] [blame] | 1540 | |
| 1541 | The |
| 1542 | .B lease |
Simon Kelley | a953096 | 2012-03-20 22:07:35 +0000 | [diff] [blame] | 1543 | function receives the information detailed in |
Simon Kelley | 57f460d | 2012-02-16 20:00:32 +0000 | [diff] [blame] | 1544 | .B --dhcp-script. |
| 1545 | It gets two arguments, firstly the action, which is a string |
| 1546 | containing, "add", "old" or "del", and secondly a table of tag value |
| 1547 | pairs. The tags mostly correspond to the environment variables |
| 1548 | detailed above, for instance the tag "domain" holds the same data as |
| 1549 | the environment variable DNSMASQ_DOMAIN. There are a few extra tags |
| 1550 | which hold the data supplied as arguments to |
| 1551 | .B --dhcp-script. |
| 1552 | These are |
| 1553 | .B mac_address, ip_address |
| 1554 | and |
| 1555 | .B hostname |
| 1556 | for IPv4, and |
| 1557 | .B client_duid, ip_address |
| 1558 | and |
| 1559 | .B hostname |
Simon Kelley | a953096 | 2012-03-20 22:07:35 +0000 | [diff] [blame] | 1560 | for IPv6. |
| 1561 | |
| 1562 | The |
| 1563 | .B tftp |
| 1564 | function is called in the same way as the lease function, and the |
| 1565 | table holds the tags |
| 1566 | .B destination_address, |
| 1567 | .B file_name |
| 1568 | and |
| 1569 | .B file_size. |
Simon Kelley | 57f460d | 2012-02-16 20:00:32 +0000 | [diff] [blame] | 1570 | .TP |
Simon Kelley | 9e03894 | 2008-05-30 20:06:34 +0100 | [diff] [blame] | 1571 | .B --dhcp-scriptuser |
Simon Kelley | 57f460d | 2012-02-16 20:00:32 +0000 | [diff] [blame] | 1572 | Specify the user as which to run the lease-change script or Lua script. This defaults to root, but can be changed to another user using this flag. |
Simon Kelley | 208b65c | 2006-08-05 21:41:37 +0100 | [diff] [blame] | 1573 | .TP |
| 1574 | .B \-9, --leasefile-ro |
| 1575 | Completely suppress use of the lease database file. The file will not |
| 1576 | be created, read, or written. Change the way the lease-change |
| 1577 | script (if one is provided) is called, so that the lease database may |
| 1578 | be maintained in external storage by the script. In addition to the |
Simon Kelley | f2621c7 | 2007-04-29 19:47:21 +0100 | [diff] [blame] | 1579 | invocations given in |
Simon Kelley | 208b65c | 2006-08-05 21:41:37 +0100 | [diff] [blame] | 1580 | .B --dhcp-script |
| 1581 | the lease-change script is called once, at dnsmasq startup, with the |
| 1582 | single argument "init". When called like this the script should write |
| 1583 | the saved state of the lease database, in dnsmasq leasefile format, to |
| 1584 | stdout and exit with zero exit code. Setting this |
| 1585 | option also forces the leasechange script to be called on changes |
| 1586 | to the client-id and lease length and expiry time. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1587 | .TP |
Simon Kelley | 832af0b | 2007-01-21 20:01:28 +0000 | [diff] [blame] | 1588 | .B --bridge-interface=<interface>,<alias>[,<alias>] |
| 1589 | Treat DHCP request packets arriving at any of the <alias> interfaces |
Simon Kelley | 7622fc0 | 2009-06-04 20:32:05 +0100 | [diff] [blame] | 1590 | as if they had arrived at <interface>. This option is necessary when |
| 1591 | using "old style" bridging on BSD platforms, since |
Simon Kelley | 832af0b | 2007-01-21 20:01:28 +0000 | [diff] [blame] | 1592 | packets arrive at tap interfaces which don't have an IP address. |
Neil Jerram | 70772c9 | 2014-06-11 21:22:40 +0100 | [diff] [blame] | 1593 | A trailing '*' wildcard can be used in each <alias>. |
Simon Kelley | 832af0b | 2007-01-21 20:01:28 +0000 | [diff] [blame] | 1594 | .TP |
Simon Kelley | 28866e9 | 2011-02-14 20:19:14 +0000 | [diff] [blame] | 1595 | .B \-s, --domain=<domain>[,<address range>[,local]] |
Simon Kelley | 9009d74 | 2008-11-14 20:04:27 +0000 | [diff] [blame] | 1596 | Specifies DNS domains for the DHCP server. Domains may be be given |
| 1597 | unconditionally (without the IP range) or for limited IP ranges. This has two effects; |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1598 | firstly it causes the DHCP server to return the domain to any hosts |
| 1599 | which request it, and secondly it sets the domain which it is legal |
Simon Kelley | 1b7ecd1 | 2007-02-05 14:57:57 +0000 | [diff] [blame] | 1600 | for DHCP-configured hosts to claim. The intention is to constrain |
| 1601 | hostnames so that an untrusted host on the LAN cannot advertise |
| 1602 | its name via dhcp as e.g. "microsoft.com" and capture traffic not |
| 1603 | meant for it. If no domain suffix is specified, then any DHCP |
| 1604 | hostname with a domain part (ie with a period) will be disallowed |
| 1605 | and logged. If suffix is specified, then hostnames with a domain |
| 1606 | part are allowed, provided the domain part matches the suffix. In |
| 1607 | addition, when a suffix is set then hostnames without a domain |
| 1608 | part have the suffix added as an optional domain part. Eg on my network I can set |
Simon Kelley | 3d8df26 | 2005-08-29 12:19:27 +0100 | [diff] [blame] | 1609 | .B --domain=thekelleys.org.uk |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1610 | and have a machine whose DHCP hostname is "laptop". The IP address for that machine is available from |
| 1611 | .B dnsmasq |
Simon Kelley | de37951 | 2004-06-22 20:23:33 +0100 | [diff] [blame] | 1612 | both as "laptop" and "laptop.thekelleys.org.uk". If the domain is |
| 1613 | given as "#" then the domain is read from the first "search" directive |
Simon Kelley | 28866e9 | 2011-02-14 20:19:14 +0000 | [diff] [blame] | 1614 | in /etc/resolv.conf (or equivalent). |
| 1615 | |
| 1616 | The address range can be of the form |
Simon Kelley | 9009d74 | 2008-11-14 20:04:27 +0000 | [diff] [blame] | 1617 | <ip address>,<ip address> or <ip address>/<netmask> or just a single |
| 1618 | <ip address>. See |
| 1619 | .B --dhcp-fqdn |
| 1620 | which can change the behaviour of dnsmasq with domains. |
Simon Kelley | 28866e9 | 2011-02-14 20:19:14 +0000 | [diff] [blame] | 1621 | |
| 1622 | If the address range is given as ip-address/network-size, then a |
| 1623 | additional flag "local" may be supplied which has the effect of adding |
| 1624 | --local declarations for forward and reverse DNS queries. Eg. |
| 1625 | .B --domain=thekelleys.org.uk,192.168.0.0/24,local |
| 1626 | is identical to |
| 1627 | .B --domain=thekelleys.org.uk,192.168.0.0/24 |
| 1628 | --local=/thekelleys.org.uk/ --local=/0.168.192.in-addr.arpa/ |
| 1629 | The network size must be 8, 16 or 24 for this to be legal. |
Simon Kelley | 9009d74 | 2008-11-14 20:04:27 +0000 | [diff] [blame] | 1630 | .TP |
| 1631 | .B --dhcp-fqdn |
| 1632 | In the default mode, dnsmasq inserts the unqualified names of |
| 1633 | DHCP clients into the DNS. For this reason, the names must be unique, |
| 1634 | even if two clients which have the same name are in different |
| 1635 | domains. If a second DHCP client appears which has the same name as an |
Tomas Hozza | a66d36e | 2013-04-22 15:08:07 +0100 | [diff] [blame] | 1636 | existing client, the name is transferred to the new client. If |
Simon Kelley | 9009d74 | 2008-11-14 20:04:27 +0000 | [diff] [blame] | 1637 | .B --dhcp-fqdn |
| 1638 | is set, this behaviour changes: the unqualified name is no longer |
| 1639 | put in the DNS, only the qualified name. Two DHCP clients with the |
| 1640 | same name may both keep the name, provided that the domain part is |
| 1641 | different (ie the fully qualified names differ.) To ensure that all |
| 1642 | names have a domain part, there must be at least |
| 1643 | .B --domain |
| 1644 | without an address specified when |
| 1645 | .B --dhcp-fqdn |
| 1646 | is set. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1647 | .TP |
Simon Kelley | c72daea | 2012-01-05 21:33:27 +0000 | [diff] [blame] | 1648 | .B --dhcp-client-update |
| 1649 | Normally, when giving a DHCP lease, dnsmasq sets flags in the FQDN |
| 1650 | option to tell the client not to attempt a DDNS update with its name |
| 1651 | and IP address. This is because the name-IP pair is automatically |
| 1652 | added into dnsmasq's DNS view. This flag suppresses that behaviour, |
| 1653 | this is useful, for instance, to allow Windows clients to update |
| 1654 | Active Directory servers. See RFC 4702 for details. |
| 1655 | .TP |
Simon Kelley | c5ad4e7 | 2012-02-24 16:06:20 +0000 | [diff] [blame] | 1656 | .B --enable-ra |
| 1657 | Enable dnsmasq's IPv6 Router Advertisement feature. DHCPv6 doesn't |
| 1658 | handle complete network configuration in the same way as DHCPv4. Router |
| 1659 | discovery and (possibly) prefix discovery for autonomous address |
| 1660 | creation are handled by a different protocol. When DHCP is in use, |
| 1661 | only a subset of this is needed, and dnsmasq can handle it, using |
| 1662 | existing DHCP configuration to provide most data. When RA is enabled, |
| 1663 | dnsmasq will advertise a prefix for each dhcp-range, with default |
| 1664 | router and recursive DNS server as the relevant link-local address on |
Simon Kelley | e8ca69e | 2012-03-26 21:23:26 +0100 | [diff] [blame] | 1665 | the machine running dnsmasq. By default, he "managed address" bits are set, and |
| 1666 | the "use SLAAC" bit is reset. This can be changed for individual |
| 1667 | subnets with the mode keywords described in |
| 1668 | .B --dhcp-range. |
Simon Kelley | 18f0fb0 | 2012-03-31 21:18:55 +0100 | [diff] [blame] | 1669 | RFC6106 DNS parameters are included in the advertisements. By default, |
| 1670 | the relevant link-local address of the machine running dnsmasq is sent |
| 1671 | as recursive DNS server. If provided, the DHCPv6 options dns-server and |
| 1672 | domain-search are used for RDNSS and DNSSL. |
Simon Kelley | c5ad4e7 | 2012-02-24 16:06:20 +0000 | [diff] [blame] | 1673 | .TP |
Simon Kelley | c4cd95d | 2013-10-10 20:58:11 +0100 | [diff] [blame] | 1674 | .B --ra-param=<interface>,[high|low],[[<ra-interval>],<router lifetime>] |
| 1675 | Set non-default values for router advertisements sent via an |
| 1676 | interface. The priority field for the router may be altered from the |
| 1677 | default of medium with eg |
| 1678 | .B --ra-param=eth0,high. |
| 1679 | The interval between router advertisements may be set (in seconds) with |
| 1680 | .B --ra-param=eth0,60. |
| 1681 | The lifetime of the route may be changed or set to zero, which allows |
| 1682 | a router to advertise prefixes but not a route via itself. |
| 1683 | .B --ra-parm=eth0,0,0 |
| 1684 | (A value of zero for the interval means the default value.) All three parameters may be set at once. |
| 1685 | .B --ra-param=low,60,1200 |
| 1686 | The interface field may include a wildcard. |
Simon Kelley | 8d03046 | 2013-07-29 15:41:26 +0100 | [diff] [blame] | 1687 | .TP |
Simon Kelley | 2937f8a | 2013-07-29 19:49:07 +0100 | [diff] [blame] | 1688 | .B --enable-tftp[=<interface>[,<interface>]] |
Simon Kelley | 832af0b | 2007-01-21 20:01:28 +0000 | [diff] [blame] | 1689 | Enable the TFTP server function. This is deliberately limited to that |
Simon Kelley | 9e03894 | 2008-05-30 20:06:34 +0100 | [diff] [blame] | 1690 | needed to net-boot a client. Only reading is allowed; the tsize and |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1691 | blksize extensions are supported (tsize is only supported in octet |
Simon Kelley | 2937f8a | 2013-07-29 19:49:07 +0100 | [diff] [blame] | 1692 | mode). Without an argument, the TFTP service is provided to the same set of interfaces as DHCP service. |
| 1693 | If the list of interfaces is provided, that defines which interfaces recieve TFTP service. |
Simon Kelley | b8187c8 | 2005-11-26 21:46:27 +0000 | [diff] [blame] | 1694 | .TP |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1695 | .B --tftp-root=<directory>[,<interface>] |
Simon Kelley | 832af0b | 2007-01-21 20:01:28 +0000 | [diff] [blame] | 1696 | Look for files to transfer using TFTP relative to the given |
| 1697 | directory. When this is set, TFTP paths which include ".." are |
| 1698 | rejected, to stop clients getting outside the specified root. |
Simon Kelley | f2621c7 | 2007-04-29 19:47:21 +0100 | [diff] [blame] | 1699 | Absolute paths (starting with /) are allowed, but they must be within |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1700 | the tftp-root. If the optional interface argument is given, the |
| 1701 | directory is only used for TFTP requests via that interface. |
Simon Kelley | 832af0b | 2007-01-21 20:01:28 +0000 | [diff] [blame] | 1702 | .TP |
Simon Kelley | 5aabfc7 | 2007-08-29 11:24:47 +0100 | [diff] [blame] | 1703 | .B --tftp-unique-root |
| 1704 | Add the IP address of the TFTP client as a path component on the end |
| 1705 | of the TFTP-root (in standard dotted-quad format). Only valid if a |
| 1706 | tftp-root is set and the directory exists. For instance, if tftp-root is "/tftp" and client |
| 1707 | 1.2.3.4 requests file "myfile" then the effective path will be |
| 1708 | "/tftp/1.2.3.4/myfile" if /tftp/1.2.3.4 exists or /tftp/myfile otherwise. |
| 1709 | .TP |
Simon Kelley | 832af0b | 2007-01-21 20:01:28 +0000 | [diff] [blame] | 1710 | .B --tftp-secure |
Simon Kelley | 5aabfc7 | 2007-08-29 11:24:47 +0100 | [diff] [blame] | 1711 | Enable TFTP secure mode: without this, any file which is readable by |
Simon Kelley | 832af0b | 2007-01-21 20:01:28 +0000 | [diff] [blame] | 1712 | the dnsmasq process under normal unix access-control rules is |
| 1713 | available via TFTP. When the --tftp-secure flag is given, only files |
| 1714 | owned by the user running the dnsmasq process are accessible. If |
| 1715 | dnsmasq is being run as root, different rules apply: --tftp-secure |
Simon Kelley | 1b7ecd1 | 2007-02-05 14:57:57 +0000 | [diff] [blame] | 1716 | has no effect, but only files which have the world-readable bit set |
Simon Kelley | 832af0b | 2007-01-21 20:01:28 +0000 | [diff] [blame] | 1717 | are accessible. It is not recommended to run dnsmasq as root with TFTP |
| 1718 | enabled, and certainly not without specifying --tftp-root. Doing so |
| 1719 | can expose any world-readable file on the server to any host on the net. |
| 1720 | .TP |
Simon Kelley | 61ce600 | 2012-04-20 21:28:49 +0100 | [diff] [blame] | 1721 | .B --tftp-lowercase |
| 1722 | Convert filenames in TFTP requests to all lowercase. This is useful |
| 1723 | for requests from Windows machines, which have case-insensitive |
| 1724 | filesystems and tend to play fast-and-loose with case in filenames. |
| 1725 | Note that dnsmasq's tftp server always converts "\\" to "/" in filenames. |
| 1726 | .TP |
Simon Kelley | 832af0b | 2007-01-21 20:01:28 +0000 | [diff] [blame] | 1727 | .B --tftp-max=<connections> |
| 1728 | Set the maximum number of concurrent TFTP connections allowed. This |
| 1729 | defaults to 50. When serving a large number of TFTP connections, |
| 1730 | per-process file descriptor limits may be encountered. Dnsmasq needs |
| 1731 | one file descriptor for each concurrent TFTP connection and one |
| 1732 | file descriptor per unique file (plus a few others). So serving the |
| 1733 | same file simultaneously to n clients will use require about n + 10 file |
| 1734 | descriptors, serving different files simultaneously to n clients will |
Simon Kelley | 824af85 | 2008-02-12 20:43:05 +0000 | [diff] [blame] | 1735 | require about (2*n) + 10 descriptors. If |
| 1736 | .B --tftp-port-range |
| 1737 | is given, that can affect the number of concurrent connections. |
Simon Kelley | 6b01084 | 2007-02-12 20:32:07 +0000 | [diff] [blame] | 1738 | .TP |
| 1739 | .B --tftp-no-blocksize |
| 1740 | Stop the TFTP server from negotiating the "blocksize" option with a |
| 1741 | client. Some buggy clients request this option but then behave badly |
| 1742 | when it is granted. |
Simon Kelley | 824af85 | 2008-02-12 20:43:05 +0000 | [diff] [blame] | 1743 | .TP |
| 1744 | .B --tftp-port-range=<start>,<end> |
| 1745 | A TFTP server listens on a well-known port (69) for connection initiation, |
| 1746 | but it also uses a dynamically-allocated port for each |
| 1747 | connection. Normally these are allocated by the OS, but this option |
| 1748 | specifies a range of ports for use by TFTP transfers. This can be |
| 1749 | useful when TFTP has to traverse a firewall. The start of the range |
| 1750 | cannot be lower than 1025 unless dnsmasq is running as root. The number |
| 1751 | of concurrent TFTP connections is limited by the size of the port range. |
Simon Kelley | 832af0b | 2007-01-21 20:01:28 +0000 | [diff] [blame] | 1752 | .TP |
Simon Kelley | b8187c8 | 2005-11-26 21:46:27 +0000 | [diff] [blame] | 1753 | .B \-C, --conf-file=<file> |
| 1754 | Specify a different configuration file. The conf-file option is also allowed in |
Simon Kelley | 28866e9 | 2011-02-14 20:19:14 +0000 | [diff] [blame] | 1755 | configuration files, to include multiple configuration files. A |
| 1756 | filename of "-" causes dnsmasq to read configuration from stdin. |
Simon Kelley | 849a835 | 2006-06-09 21:02:31 +0100 | [diff] [blame] | 1757 | .TP |
Simon Kelley | 3e1551a | 2014-09-09 21:46:07 +0100 | [diff] [blame] | 1758 | .B \-7, --conf-dir=<directory>[,<file-extension>......], |
Simon Kelley | 849a835 | 2006-06-09 21:02:31 +0100 | [diff] [blame] | 1759 | Read all the files in the given directory as configuration |
Simon Kelley | 1f15b81 | 2009-10-13 17:49:32 +0100 | [diff] [blame] | 1760 | files. If extension(s) are given, any files which end in those |
| 1761 | extensions are skipped. Any files whose names end in ~ or start with . or start and end |
Simon Kelley | 3e1551a | 2014-09-09 21:46:07 +0100 | [diff] [blame] | 1762 | with # are always skipped. If the extension starts with * then only files |
| 1763 | which have that extension are loaded. So |
| 1764 | .B --conf-dir=/path/to/dir,*.conf |
| 1765 | loads all files with the suffix .conf in /path/to/dir. This flag may be given on the command |
| 1766 | line or in a configuration file. If giving it on the command line, be sure to |
| 1767 | escape * characters. |
Simon Kelley | 7b1eae4 | 2014-02-20 13:43:28 +0000 | [diff] [blame] | 1768 | .TP |
| 1769 | .B --servers-file=<file> |
| 1770 | A special case of |
| 1771 | .B --conf-file |
| 1772 | which differs in two respects. Firstly, only --server and --rev-server are allowed |
| 1773 | in the configuration file included. Secondly, the file is re-read and the configuration |
| 1774 | therein is updated when dnsmasq recieves SIGHUP. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1775 | .SH CONFIG FILE |
Simon Kelley | 3be3454 | 2004-09-11 19:12:13 +0100 | [diff] [blame] | 1776 | At startup, dnsmasq reads |
| 1777 | .I /etc/dnsmasq.conf, |
| 1778 | if it exists. (On |
| 1779 | FreeBSD, the file is |
| 1780 | .I /usr/local/etc/dnsmasq.conf |
Simon Kelley | b8187c8 | 2005-11-26 21:46:27 +0000 | [diff] [blame] | 1781 | ) (but see the |
| 1782 | .B \-C |
Simon Kelley | 849a835 | 2006-06-09 21:02:31 +0100 | [diff] [blame] | 1783 | and |
| 1784 | .B \-7 |
| 1785 | options.) The format of this |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1786 | file consists of one option per line, exactly as the long options detailed |
| 1787 | in the OPTIONS section but without the leading "--". Lines starting with # are comments and ignored. For |
Simon Kelley | b49644f | 2004-01-30 21:36:24 +0000 | [diff] [blame] | 1788 | options which may only be specified once, the configuration file overrides |
Simon Kelley | b8187c8 | 2005-11-26 21:46:27 +0000 | [diff] [blame] | 1789 | the command line. Quoting is allowed in a config file: |
Simon Kelley | 3d8df26 | 2005-08-29 12:19:27 +0100 | [diff] [blame] | 1790 | between " quotes the special meanings of ,:. and # are removed and the |
Simon Kelley | 824af85 | 2008-02-12 20:43:05 +0000 | [diff] [blame] | 1791 | following escapes are allowed: \\\\ \\" \\t \\e \\b \\r and \\n. The later |
| 1792 | corresponding to tab, escape, backspace, return and newline. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1793 | .SH NOTES |
| 1794 | When it receives a SIGHUP, |
| 1795 | .B dnsmasq |
Simon Kelley | 3be3454 | 2004-09-11 19:12:13 +0100 | [diff] [blame] | 1796 | clears its cache and then re-loads |
Simon Kelley | 5aabfc7 | 2007-08-29 11:24:47 +0100 | [diff] [blame] | 1797 | .I /etc/hosts |
| 1798 | and |
| 1799 | .I /etc/ethers |
Simon Kelley | 3d04f46 | 2015-01-31 21:59:13 +0000 | [diff] [blame] | 1800 | and any file given by --dhcp-hostsfile, --dhcp-hostsdir, --dhcp-optsfile, |
| 1801 | --dhcp-optsdir, --addn-hosts or --hostsdir. |
Simon Kelley | 5aabfc7 | 2007-08-29 11:24:47 +0100 | [diff] [blame] | 1802 | The dhcp lease change script is called for all |
| 1803 | existing DHCP leases. If |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1804 | .B |
| 1805 | --no-poll |
Simon Kelley | 3be3454 | 2004-09-11 19:12:13 +0100 | [diff] [blame] | 1806 | is set SIGHUP also re-reads |
| 1807 | .I /etc/resolv.conf. |
| 1808 | SIGHUP |
Simon Kelley | b49644f | 2004-01-30 21:36:24 +0000 | [diff] [blame] | 1809 | does NOT re-read the configuration file. |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1810 | .PP |
| 1811 | When it receives a SIGUSR1, |
| 1812 | .B dnsmasq |
Simon Kelley | 824af85 | 2008-02-12 20:43:05 +0000 | [diff] [blame] | 1813 | writes statistics to the system log. It writes the cache size, |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1814 | the number of names which have had to removed from the cache before |
| 1815 | they expired in order to make room for new names and the total number |
Simon Kelley | fec216d | 2014-03-27 20:54:34 +0000 | [diff] [blame] | 1816 | of names that have been inserted into the cache. The number of cache hits and |
| 1817 | misses and the number of authoritative queries answered are also given. For each upstream |
Simon Kelley | 824af85 | 2008-02-12 20:43:05 +0000 | [diff] [blame] | 1818 | server it gives the number of queries sent, and the number which |
| 1819 | resulted in an error. In |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1820 | .B --no-daemon |
Simon Kelley | 5aabfc7 | 2007-08-29 11:24:47 +0100 | [diff] [blame] | 1821 | mode or when full logging is enabled (-q), a complete dump of the |
Simon Kelley | fec216d | 2014-03-27 20:54:34 +0000 | [diff] [blame] | 1822 | contents of the cache is made. |
| 1823 | |
| 1824 | The cache statistics are also available in the DNS as answers to |
| 1825 | queries of class CHAOS and type TXT in domain bind. The domain names are cachesize.bind, insertions.bind, evictions.bind, |
| 1826 | misses.bind, hits.bind, auth.bind and servers.bind. An example command to query this, using the |
| 1827 | .B dig |
| 1828 | utility would be |
| 1829 | |
| 1830 | dig +short chaos txt cachesize.bind |
| 1831 | |
Simon Kelley | 5aabfc7 | 2007-08-29 11:24:47 +0100 | [diff] [blame] | 1832 | .PP |
| 1833 | When it receives SIGUSR2 and it is logging direct to a file (see |
| 1834 | .B --log-facility |
| 1835 | ) |
| 1836 | .B dnsmasq |
| 1837 | will close and reopen the log file. Note that during this operation, |
| 1838 | dnsmasq will not be running as root. When it first creates the logfile |
| 1839 | dnsmasq changes the ownership of the file to the non-root user it will run |
| 1840 | as. Logrotate should be configured to create a new log file with |
Simon Kelley | 9e03894 | 2008-05-30 20:06:34 +0100 | [diff] [blame] | 1841 | the ownership which matches the existing one before sending SIGUSR2. |
Simon Kelley | 5aabfc7 | 2007-08-29 11:24:47 +0100 | [diff] [blame] | 1842 | If TCP DNS queries are in progress, the old logfile will remain open in |
| 1843 | child processes which are handling TCP queries and may continue to be |
| 1844 | written. There is a limit of 150 seconds, after which all existing TCP |
| 1845 | processes will have expired: for this reason, it is not wise to |
| 1846 | configure logfile compression for logfiles which have just been |
| 1847 | rotated. Using logrotate, the required options are |
| 1848 | .B create |
| 1849 | and |
| 1850 | .B delaycompress. |
| 1851 | |
| 1852 | |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1853 | .PP |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1854 | Dnsmasq is a DNS query forwarder: it it not capable of recursively |
| 1855 | answering arbitrary queries starting from the root servers but |
| 1856 | forwards such queries to a fully recursive upstream DNS server which is |
| 1857 | typically provided by an ISP. By default, dnsmasq reads |
Simon Kelley | 3be3454 | 2004-09-11 19:12:13 +0100 | [diff] [blame] | 1858 | .I /etc/resolv.conf |
| 1859 | to discover the IP |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1860 | addresses of the upstream nameservers it should use, since the |
| 1861 | information is typically stored there. Unless |
| 1862 | .B --no-poll |
| 1863 | is used, |
| 1864 | .B dnsmasq |
Simon Kelley | 3be3454 | 2004-09-11 19:12:13 +0100 | [diff] [blame] | 1865 | checks the modification time of |
| 1866 | .I /etc/resolv.conf |
| 1867 | (or equivalent if |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1868 | .B \--resolv-file |
| 1869 | is used) and re-reads it if it changes. This allows the DNS servers to |
| 1870 | be set dynamically by PPP or DHCP since both protocols provide the |
| 1871 | information. |
Simon Kelley | 3be3454 | 2004-09-11 19:12:13 +0100 | [diff] [blame] | 1872 | Absence of |
| 1873 | .I /etc/resolv.conf |
| 1874 | is not an error |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1875 | since it may not have been created before a PPP connection exists. Dnsmasq |
Simon Kelley | 3be3454 | 2004-09-11 19:12:13 +0100 | [diff] [blame] | 1876 | simply keeps checking in case |
| 1877 | .I /etc/resolv.conf |
| 1878 | is created at any |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1879 | time. Dnsmasq can be told to parse more than one resolv.conf |
| 1880 | file. This is useful on a laptop, where both PPP and DHCP may be used: |
Simon Kelley | 3be3454 | 2004-09-11 19:12:13 +0100 | [diff] [blame] | 1881 | dnsmasq can be set to poll both |
| 1882 | .I /etc/ppp/resolv.conf |
| 1883 | and |
| 1884 | .I /etc/dhcpc/resolv.conf |
| 1885 | and will use the contents of whichever changed |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1886 | last, giving automatic switching between DNS servers. |
| 1887 | .PP |
| 1888 | Upstream servers may also be specified on the command line or in |
Simon Kelley | b49644f | 2004-01-30 21:36:24 +0000 | [diff] [blame] | 1889 | the configuration file. These server specifications optionally take a |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 1890 | domain name which tells dnsmasq to use that server only to find names |
| 1891 | in that particular domain. |
| 1892 | .PP |
| 1893 | In order to configure dnsmasq to act as cache for the host on which it is running, put "nameserver 127.0.0.1" in |
| 1894 | .I /etc/resolv.conf |
| 1895 | to force local processes to send queries to |
| 1896 | dnsmasq. Then either specify the upstream servers directly to dnsmasq |
| 1897 | using |
| 1898 | .B \--server |
| 1899 | options or put their addresses real in another file, say |
| 1900 | .I /etc/resolv.dnsmasq |
| 1901 | and run dnsmasq with the |
| 1902 | .B \-r /etc/resolv.dnsmasq |
| 1903 | option. This second technique allows for dynamic update of the server |
| 1904 | addresses by PPP or DHCP. |
Simon Kelley | 3be3454 | 2004-09-11 19:12:13 +0100 | [diff] [blame] | 1905 | .PP |
Simon Kelley | f6b7dc4 | 2005-01-23 12:06:08 +0000 | [diff] [blame] | 1906 | Addresses in /etc/hosts will "shadow" different addresses for the same |
| 1907 | names in the upstream DNS, so "mycompany.com 1.2.3.4" in /etc/hosts will ensure that |
| 1908 | queries for "mycompany.com" always return 1.2.3.4 even if queries in |
| 1909 | the upstream DNS would otherwise return a different address. There is |
| 1910 | one exception to this: if the upstream DNS contains a CNAME which |
| 1911 | points to a shadowed name, then looking up the CNAME through dnsmasq |
| 1912 | will result in the unshadowed address associated with the target of |
| 1913 | the CNAME. To work around this, add the CNAME to /etc/hosts so that |
| 1914 | the CNAME is shadowed too. |
| 1915 | |
| 1916 | .PP |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1917 | The tag system works as follows: For each DHCP request, dnsmasq |
| 1918 | collects a set of valid tags from active configuration lines which |
| 1919 | include set:<tag>, including one from the |
Simon Kelley | 26128d2 | 2004-11-14 16:43:54 +0000 | [diff] [blame] | 1920 | .B dhcp-range |
| 1921 | used to allocate the address, one from any matching |
| 1922 | .B dhcp-host |
Simon Kelley | 9009d74 | 2008-11-14 20:04:27 +0000 | [diff] [blame] | 1923 | (and "known" if a dhcp-host matches) |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1924 | The tag "bootp" is set for BOOTP requests, and a tag whose name is the |
| 1925 | name of the interface on which the request arrived is also set. |
| 1926 | |
Tomas Hozza | a66d36e | 2013-04-22 15:08:07 +0100 | [diff] [blame] | 1927 | Any configuration lines which include one or more tag:<tag> constructs |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1928 | will only be valid if all that tags are matched in the set derived |
| 1929 | above. Typically this is dhcp-option. |
Simon Kelley | 26128d2 | 2004-11-14 16:43:54 +0000 | [diff] [blame] | 1930 | .B dhcp-option |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1931 | which has tags will be used in preference to an untagged |
Simon Kelley | 26128d2 | 2004-11-14 16:43:54 +0000 | [diff] [blame] | 1932 | .B dhcp-option, |
| 1933 | provided that _all_ the tags match somewhere in the |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1934 | set collected as described above. The prefix '!' on a tag means 'not' |
Moritz Warning | e62e9b6 | 2014-03-20 15:32:22 +0000 | [diff] [blame] | 1935 | so --dhcp-option=tag:!purple,3,1.2.3.4 sends the option when the |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1936 | tag purple is not in the set of valid tags. (If using this in a |
| 1937 | command line rather than a configuration file, be sure to escape !, |
| 1938 | which is a shell metacharacter) |
Simon Kelley | 7de060b | 2011-08-26 17:24:52 +0100 | [diff] [blame] | 1939 | |
| 1940 | When selecting dhcp-options, a tag from dhcp-range is second class |
| 1941 | relative to other tags, to make it easy to override options for |
| 1942 | individual hosts, so |
| 1943 | .B dhcp-range=set:interface1,...... |
| 1944 | .B dhcp-host=set:myhost,..... |
| 1945 | .B dhcp-option=tag:interface1,option:nis-domain,"domain1" |
| 1946 | .B dhcp-option=tag:myhost,option:nis-domain,"domain2" |
| 1947 | will set the NIS-domain to domain1 for hosts in the range, but |
| 1948 | override that to domain2 for a particular host. |
| 1949 | |
Simon Kelley | 26128d2 | 2004-11-14 16:43:54 +0000 | [diff] [blame] | 1950 | .PP |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1951 | Note that for |
Simon Kelley | f6b7dc4 | 2005-01-23 12:06:08 +0000 | [diff] [blame] | 1952 | .B dhcp-range |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1953 | both tag:<tag> and set:<tag> are allowed, to both select the range in |
| 1954 | use based on (eg) dhcp-host, and to affect the options sent, based on |
| 1955 | the range selected. |
| 1956 | |
| 1957 | This system evolved from an earlier, more limited one and for backward |
| 1958 | compatibility "net:" may be used instead of "tag:" and "set:" may be |
| 1959 | omitted. (Except in |
| 1960 | .B dhcp-host, |
| 1961 | where "net:" may be used instead of "set:".) For the same reason, '#' |
| 1962 | may be used instead of '!' to indicate NOT. |
Simon Kelley | f6b7dc4 | 2005-01-23 12:06:08 +0000 | [diff] [blame] | 1963 | .PP |
Simon Kelley | 3be3454 | 2004-09-11 19:12:13 +0100 | [diff] [blame] | 1964 | The DHCP server in dnsmasq will function as a BOOTP server also, |
| 1965 | provided that the MAC address and IP address for clients are given, |
| 1966 | either using |
| 1967 | .B dhcp-host |
| 1968 | configurations or in |
| 1969 | .I /etc/ethers |
| 1970 | , and a |
| 1971 | .B dhcp-range |
| 1972 | configuration option is present to activate the DHCP server |
Simon Kelley | b8187c8 | 2005-11-26 21:46:27 +0000 | [diff] [blame] | 1973 | on a particular network. (Setting --bootp-dynamic removes the need for |
| 1974 | static address mappings.) The filename |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 1975 | parameter in a BOOTP request is used as a tag, |
| 1976 | as is the tag "bootp", allowing some control over the options returned to |
Simon Kelley | 3be3454 | 2004-09-11 19:12:13 +0100 | [diff] [blame] | 1977 | different classes of hosts. |
| 1978 | |
Simon Kelley | 333b2ce | 2013-01-07 21:46:03 +0000 | [diff] [blame] | 1979 | .SH AUTHORITATIVE CONFIGURATION |
| 1980 | .PP |
| 1981 | Configuring dnsmasq to act as an authoritative DNS server is |
| 1982 | complicated by the fact that it involves configuration of external DNS |
| 1983 | servers to provide delegation. We will walk through three scenarios of |
| 1984 | increasing complexity. Prerequisites for all of these scenarios |
Simon Kelley | 81925ab | 2013-04-10 11:43:58 +0100 | [diff] [blame] | 1985 | are a globally accessible IP address, an A or AAAA record pointing to that address, |
Simon Kelley | 333b2ce | 2013-01-07 21:46:03 +0000 | [diff] [blame] | 1986 | and an external DNS server capable of doing delegation of the zone in |
| 1987 | question. For the first part of this explanation, we will call the A (or AAAA) record |
| 1988 | for the globally accessible address server.example.com, and the zone |
| 1989 | for which dnsmasq is authoritative our.zone.com. |
| 1990 | |
| 1991 | The simplest configuration consists of two lines of dnsmasq configuration; something like |
| 1992 | |
| 1993 | .nf |
| 1994 | .B auth-server=server.example.com,eth0 |
Simon Kelley | 79cb46c | 2013-01-23 19:49:21 +0000 | [diff] [blame] | 1995 | .B auth-zone=our.zone.com,1.2.3.0/24 |
Simon Kelley | 333b2ce | 2013-01-07 21:46:03 +0000 | [diff] [blame] | 1996 | .fi |
| 1997 | |
| 1998 | and two records in the external DNS |
| 1999 | |
| 2000 | .nf |
| 2001 | server.example.com A 192.0.43.10 |
| 2002 | our.zone.com NS server.example.com |
| 2003 | .fi |
| 2004 | |
| 2005 | eth0 is the external network interface on which dnsmasq is listening, |
| 2006 | and has (globally accessible) address 192.0.43.10. |
| 2007 | |
| 2008 | Note that the external IP address may well be dynamic (ie assigned |
| 2009 | from an ISP by DHCP or PPP) If so, the A record must be linked to this |
| 2010 | dynamic assignment by one of the usual dynamic-DNS systems. |
| 2011 | |
| 2012 | A more complex, but practically useful configuration has the address |
| 2013 | record for the globally accessible IP address residing in the |
| 2014 | authoritative zone which dnsmasq is serving, typically at the root. Now |
| 2015 | we have |
| 2016 | |
| 2017 | .nf |
| 2018 | .B auth-server=our.zone.com,eth0 |
Simon Kelley | 79cb46c | 2013-01-23 19:49:21 +0000 | [diff] [blame] | 2019 | .B auth-zone=our.zone.com,1.2.3.0/24 |
Simon Kelley | 333b2ce | 2013-01-07 21:46:03 +0000 | [diff] [blame] | 2020 | .fi |
| 2021 | |
| 2022 | .nf |
Simon Kelley | 0f128eb | 2013-03-11 21:21:35 +0000 | [diff] [blame] | 2023 | our.zone.com A 1.2.3.4 |
Simon Kelley | 333b2ce | 2013-01-07 21:46:03 +0000 | [diff] [blame] | 2024 | our.zone.com NS our.zone.com |
| 2025 | .fi |
| 2026 | |
| 2027 | The A record for our.zone.com has now become a glue record, it solves |
| 2028 | the chicken-and-egg problem of finding the IP address of the |
| 2029 | nameserver for our.zone.com when the A record is within that |
| 2030 | zone. Note that this is the only role of this record: as dnsmasq is |
| 2031 | now authoritative from our.zone.com it too must provide this |
| 2032 | record. If the external address is static, this can be done with an |
| 2033 | .B /etc/hosts |
| 2034 | entry or |
| 2035 | .B --host-record. |
Simon Kelley | 333b2ce | 2013-01-07 21:46:03 +0000 | [diff] [blame] | 2036 | |
| 2037 | .nf |
Simon Kelley | 0f128eb | 2013-03-11 21:21:35 +0000 | [diff] [blame] | 2038 | .B auth-server=our.zone.com,eth0 |
| 2039 | .B host-record=our.zone.com,1.2.3.4 |
| 2040 | .B auth-zone=our.zone.com,1.2.3.0/24 |
| 2041 | .fi |
| 2042 | |
| 2043 | If the external address is dynamic, the address |
| 2044 | associated with our.zone.com must be derived from the address of the |
Simon Kelley | 6f130de | 2013-04-15 14:47:14 +0100 | [diff] [blame] | 2045 | relevant interface. This is done using |
Simon Kelley | 0f128eb | 2013-03-11 21:21:35 +0000 | [diff] [blame] | 2046 | .B interface-name |
| 2047 | Something like: |
| 2048 | |
| 2049 | .nf |
| 2050 | .B auth-server=our.zone.com,eth0 |
| 2051 | .B interface-name=our.zone.com,eth0 |
Simon Kelley | 32b4e4c | 2013-11-14 10:36:55 +0000 | [diff] [blame] | 2052 | .B auth-zone=our.zone.com,1.2.3.0/24,eth0 |
Simon Kelley | 333b2ce | 2013-01-07 21:46:03 +0000 | [diff] [blame] | 2053 | .fi |
| 2054 | |
Simon Kelley | 32b4e4c | 2013-11-14 10:36:55 +0000 | [diff] [blame] | 2055 | (The "eth0" argument in auth-zone adds the subnet containing eth0's |
| 2056 | dynamic address to the zone, so that the interface-name returns the |
| 2057 | address in outside queries.) |
| 2058 | |
Simon Kelley | 333b2ce | 2013-01-07 21:46:03 +0000 | [diff] [blame] | 2059 | Our final configuration builds on that above, but also adds a |
| 2060 | secondary DNS server. This is another DNS server which learns the DNS data |
| 2061 | for the zone by doing zones transfer, and acts as a backup should |
| 2062 | the primary server become inaccessible. The configuration of the |
| 2063 | secondary is beyond the scope of this man-page, but the extra |
| 2064 | configuration of dnsmasq is simple: |
| 2065 | |
| 2066 | .nf |
| 2067 | .B auth-sec-servers=secondary.myisp.com |
| 2068 | .fi |
| 2069 | |
| 2070 | and |
| 2071 | |
| 2072 | .nf |
| 2073 | our.zone.com NS secondary.myisp.com |
| 2074 | .fi |
| 2075 | |
| 2076 | Adding auth-sec-servers enables zone transfer in dnsmasq, to allow the |
| 2077 | secondary to collect the DNS data. If you wish to restrict this data |
| 2078 | to particular hosts then |
| 2079 | |
| 2080 | .nf |
| 2081 | .B auth-peer=<IP address of secondary> |
| 2082 | .fi |
| 2083 | |
| 2084 | will do so. |
| 2085 | |
| 2086 | Dnsmasq acts as an authoritative server for in-addr.arpa and |
Lutz Preßler | 1d7e0a3 | 2014-04-07 22:06:23 +0100 | [diff] [blame] | 2087 | ip6.arpa domains associated with the subnets given in auth-zone |
Simon Kelley | 333b2ce | 2013-01-07 21:46:03 +0000 | [diff] [blame] | 2088 | declarations, so reverse (address to name) lookups can be simply |
| 2089 | configured with a suitable NS record, for instance in this example, |
| 2090 | where we allow 1.2.3.0/24 addresses. |
| 2091 | |
| 2092 | .nf |
| 2093 | 3.2.1.in-addr.arpa NS our.zone.com |
| 2094 | .fi |
| 2095 | |
| 2096 | Note that at present, reverse (in-addr.arpa and ip6.arpa) zones are |
| 2097 | not available in zone transfers, so there is no point arranging |
| 2098 | secondary servers for reverse lookups. |
| 2099 | |
| 2100 | .PP |
| 2101 | When dnsmasq is configured to act as an authoritative server, the |
| 2102 | following data is used to populate the authoritative zone. |
| 2103 | .PP |
| 2104 | .B --mx-host, --srv-host, --dns-rr, --txt-record, --naptr-record |
| 2105 | , as long as the record names are in the authoritative domain. |
| 2106 | .PP |
| 2107 | .B --cname |
| 2108 | as long as the record name is in the authoritative domain. If the |
| 2109 | target of the CNAME is unqualified, then it is qualified with the |
| 2110 | authoritative zone name. |
| 2111 | .PP |
| 2112 | IPv4 and IPv6 addresses from /etc/hosts (and |
| 2113 | .B --addn-hosts |
| 2114 | ) and |
| 2115 | .B --host-record |
Simon Kelley | 376d48c | 2013-11-13 13:04:30 +0000 | [diff] [blame] | 2116 | and |
| 2117 | .B --interface-name |
Simon Kelley | 333b2ce | 2013-01-07 21:46:03 +0000 | [diff] [blame] | 2118 | provided the address falls into one of the subnets specified in the |
| 2119 | .B --auth-zone. |
| 2120 | .PP |
Simon Kelley | 333b2ce | 2013-01-07 21:46:03 +0000 | [diff] [blame] | 2121 | Addresses of DHCP leases, provided the address falls into one of the subnets specified in the |
Simon Kelley | 376d48c | 2013-11-13 13:04:30 +0000 | [diff] [blame] | 2122 | .B --auth-zone. |
| 2123 | (If contructed DHCP ranges are is use, which depend on the address dynamically |
| 2124 | assigned to an interface, then the form of |
Simon Kelley | 333b2ce | 2013-01-07 21:46:03 +0000 | [diff] [blame] | 2125 | .B --auth-zone |
Simon Kelley | 376d48c | 2013-11-13 13:04:30 +0000 | [diff] [blame] | 2126 | which defines subnets by the dynamic address of an interface should |
| 2127 | be used to ensure this condition is met.) |
| 2128 | .PP |
| 2129 | In the default mode, where a DHCP lease |
Simon Kelley | 333b2ce | 2013-01-07 21:46:03 +0000 | [diff] [blame] | 2130 | has an unqualified name, and possibly a qualified name constructed |
| 2131 | using |
| 2132 | .B --domain |
| 2133 | then the name in the authoritative zone is constructed from the |
| 2134 | unqualified name and the zone's domain. This may or may not equal |
| 2135 | that specified by |
| 2136 | .B --domain. |
| 2137 | If |
| 2138 | .B --dhcp-fqdn |
| 2139 | is set, then the fully qualified names associated with DHCP leases are |
| 2140 | used, and must match the zone's domain. |
| 2141 | |
| 2142 | |
| 2143 | |
Simon Kelley | 5aabfc7 | 2007-08-29 11:24:47 +0100 | [diff] [blame] | 2144 | .SH EXIT CODES |
| 2145 | .PP |
| 2146 | 0 - Dnsmasq successfully forked into the background, or terminated |
| 2147 | normally if backgrounding is not enabled. |
| 2148 | .PP |
| 2149 | 1 - A problem with configuration was detected. |
| 2150 | .PP |
| 2151 | 2 - A problem with network access occurred (address in use, attempt |
| 2152 | to use privileged ports without permission). |
| 2153 | .PP |
Simon Kelley | 9e03894 | 2008-05-30 20:06:34 +0100 | [diff] [blame] | 2154 | 3 - A problem occurred with a filesystem operation (missing |
Simon Kelley | 5aabfc7 | 2007-08-29 11:24:47 +0100 | [diff] [blame] | 2155 | file/directory, permissions). |
| 2156 | .PP |
| 2157 | 4 - Memory allocation failure. |
| 2158 | .PP |
| 2159 | 5 - Other miscellaneous problem. |
| 2160 | .PP |
| 2161 | 11 or greater - a non zero return code was received from the |
| 2162 | lease-script process "init" call. The exit code from dnsmasq is the |
| 2163 | script's exit code with 10 added. |
| 2164 | |
Simon Kelley | 1b7ecd1 | 2007-02-05 14:57:57 +0000 | [diff] [blame] | 2165 | .SH LIMITS |
| 2166 | The default values for resource limits in dnsmasq are generally |
| 2167 | conservative, and appropriate for embedded router type devices with |
| 2168 | slow processors and limited memory. On more capable hardware, it is |
| 2169 | possible to increase the limits, and handle many more clients. The |
| 2170 | following applies to dnsmasq-2.37: earlier versions did not scale as well. |
| 2171 | |
| 2172 | .PP |
| 2173 | Dnsmasq is capable of handling DNS and DHCP for at least a thousand |
Simon Kelley | 8ef5ada | 2010-06-03 19:42:45 +0100 | [diff] [blame] | 2174 | clients. The DHCP lease times should not be very short (less than one hour). The |
Simon Kelley | 1b7ecd1 | 2007-02-05 14:57:57 +0000 | [diff] [blame] | 2175 | value of |
| 2176 | .B --dns-forward-max |
| 2177 | can be increased: start with it equal to |
| 2178 | the number of clients and increase if DNS seems slow. Note that DNS |
| 2179 | performance depends too on the performance of the upstream |
| 2180 | nameservers. The size of the DNS cache may be increased: the hard |
| 2181 | limit is 10000 names and the default (150) is very low. Sending |
| 2182 | SIGUSR1 to dnsmasq makes it log information which is useful for tuning |
| 2183 | the cache size. See the |
| 2184 | .B NOTES |
| 2185 | section for details. |
| 2186 | |
| 2187 | .PP |
| 2188 | The built-in TFTP server is capable of many simultaneous file |
| 2189 | transfers: the absolute limit is related to the number of file-handles |
| 2190 | allowed to a process and the ability of the select() system call to |
| 2191 | cope with large numbers of file handles. If the limit is set too high |
| 2192 | using |
| 2193 | .B --tftp-max |
| 2194 | it will be scaled down and the actual limit logged at |
| 2195 | start-up. Note that more transfers are possible when the same file is |
| 2196 | being sent than when each transfer sends a different file. |
| 2197 | |
| 2198 | .PP |
| 2199 | It is possible to use dnsmasq to block Web advertising by using a list |
| 2200 | of known banner-ad servers, all resolving to 127.0.0.1 or 0.0.0.0, in |
| 2201 | .B /etc/hosts |
| 2202 | or an additional hosts file. The list can be very long, |
| 2203 | dnsmasq has been tested successfully with one million names. That size |
| 2204 | file needs a 1GHz processor and about 60Mb of RAM. |
| 2205 | |
Simon Kelley | 1f15b81 | 2009-10-13 17:49:32 +0100 | [diff] [blame] | 2206 | .SH INTERNATIONALISATION |
| 2207 | Dnsmasq can be compiled to support internationalisation. To do this, |
| 2208 | the make targets "all-i18n" and "install-i18n" should be used instead of |
| 2209 | the standard targets "all" and "install". When internationalisation |
| 2210 | is compiled in, dnsmasq will produce log messages in the local |
| 2211 | language and support internationalised domain names (IDN). Domain |
| 2212 | names in /etc/hosts, /etc/ethers and /etc/dnsmasq.conf which contain |
| 2213 | non-ASCII characters will be translated to the DNS-internal punycode |
| 2214 | representation. Note that |
| 2215 | dnsmasq determines both the language for messages and the assumed |
| 2216 | charset for configuration |
| 2217 | files from the LANG environment variable. This should be set to the system |
| 2218 | default value by the script which is responsible for starting |
| 2219 | dnsmasq. When editing the configuration files, be careful to do so |
| 2220 | using only the system-default locale and not user-specific one, since |
| 2221 | dnsmasq has no direct way of determining the charset in use, and must |
| 2222 | assume that it is the system default. |
| 2223 | |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 2224 | .SH FILES |
Simon Kelley | b49644f | 2004-01-30 21:36:24 +0000 | [diff] [blame] | 2225 | .IR /etc/dnsmasq.conf |
| 2226 | |
| 2227 | .IR /usr/local/etc/dnsmasq.conf |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 2228 | |
| 2229 | .IR /etc/resolv.conf |
Simon Kelley | 28866e9 | 2011-02-14 20:19:14 +0000 | [diff] [blame] | 2230 | .IR /var/run/dnsmasq/resolv.conf |
| 2231 | .IR /etc/ppp/resolv.conf |
| 2232 | .IR /etc/dhcpc/resolv.conf |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 2233 | |
| 2234 | .IR /etc/hosts |
| 2235 | |
Simon Kelley | 3be3454 | 2004-09-11 19:12:13 +0100 | [diff] [blame] | 2236 | .IR /etc/ethers |
| 2237 | |
Simon Kelley | b49644f | 2004-01-30 21:36:24 +0000 | [diff] [blame] | 2238 | .IR /var/lib/misc/dnsmasq.leases |
| 2239 | |
| 2240 | .IR /var/db/dnsmasq.leases |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 2241 | |
| 2242 | .IR /var/run/dnsmasq.pid |
| 2243 | .SH SEE ALSO |
Simon Kelley | 9e4abcb | 2004-01-22 19:47:41 +0000 | [diff] [blame] | 2244 | .BR hosts (5), |
| 2245 | .BR resolver (5) |
| 2246 | .SH AUTHOR |
| 2247 | This manual page was written by Simon Kelley <simon@thekelleys.org.uk>. |
| 2248 | |
| 2249 | |