| Simon Kelley | 343b7b4 | 2019-04-08 16:50:13 +0100 | [diff] [blame] | 1 | HOWTO
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| 2 | =====
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| 3 | dnsmasq comes with the possibility to run multiple systemd service instances on the same machine.
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| 4 | There is the main service which is enabled by default via `systemctl enable dnsmasq.service` and uses the configuration from `/etc/default/dnsmasq`.
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| 5 |
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| 6 | Additional service instances can be enabled via `systemctl enable dnsmasq@<instance name>.service` that use the configuration from `/etc/default/dnsmasq.<instance name>`.
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| 7 | It is recommended to use a separate configuration file and directory for each instance.
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| 8 | Additionally make sure that all instances use either different ports and/or ip addresses to avoid binding collisions.
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| 9 |
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| 10 | Example setup for an instance called "alt"
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| 11 | #1 File `/etc/dnsmasq.alt.conf` copied from `/etc/dnsmasq.conf`
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| 12 | #2 Directory `/etc/dnsmasq.alt.d`
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| 13 | #3 File `/etc/default/dnsmasq.alt` copied from `/etc/default/dnsmasq` with following adaptions:
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| 14 | * The options DNSMASQ_OPTS and CONFIG_DIR point to the correct configuration file and directory.
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| 15 | DNSMASQ_OPTS="... --conf-file=/etc/dnsmasq.alt.conf ..."
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| 16 | CONFIG_DIR=/etc/dnsmasq.alt.d,.dpkg-dist,.dpkg-old,.dpkg-new
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| 17 | * The option DNSMASQ_EXCEPT must contain "lo" to avoid that an instance becomes the machine's DNS resolver.
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| 18 | DNSMASQ_EXCEPT="lo"
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| 19 | * If the additional instance should bind to all IP addresses of a specific interface, e.g. "dnsalt01", then the following addition could be used:
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| 20 | DNSMASQ_OPTS="... --bind-dynamic --interface=dnsalt01 ..."
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| 21 | Additionally the main instance must be stopped from binding to interfaces that are used by other instances:
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| 22 | DNSMASQ_OPTS="... --bind-dynamic --except-interface=dnsalt* ..."
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| 23 | * If the additional instance should not use the machine's DNS resolver, normally that's the dnsmasq main instance, as upstream server, then the following addition could be used:
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| 24 | IGNORE_RESOLVCONF=yes
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| 25 | #4 Enable additional instance via `systemctl enable dnsmasq@alt.service`
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| 26 | #5 Start additional instance without reboot via `systemctl start dnsmasq@alt.service`
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| 27 |
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| 28 |
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| 29 |
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| 30 | TODO
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| 31 | ====
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| 32 | #1 - Found shortcoming on 2019-03-10
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| 33 | Only the option DNSMASQ_EXCEPT="lo" avoids that an DNS instance will be set as the machine's DNS resolver.
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| 34 | This may interfere with the wish to run an additional instance on a different port on the localhost addresses.
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| 35 | My suggestion in the initial Debian report [1] was to specify a explicit variable for this.
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| 36 |
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| 37 | [1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=914305#5
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| 38 |
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| 39 |
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| 40 | #2 - Preferred configuration way
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| 41 | Should the variables DNSMASQ_INTERFACE and DNSMASQ_EXCEPT be used instead of --interface and --except-interface? (while "lo" still has to be in DNSMASQ_EXCEPT as of now)
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