diff --git a/src/vnet/ip/ip4_input.h b/src/vnet/ip/ip4_input.h
new file mode 100644
index 0000000..75306a3
--- /dev/null
+++ b/src/vnet/ip/ip4_input.h
@@ -0,0 +1,223 @@
+/*
+ * Copyright (c) 2017 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/*
+ * ip/ip4_input.c: IP v4 input node
+ *
+ * Copyright (c) 2008 Eliot Dresselhaus
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ *  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ *  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ *  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ *  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ *  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef included_ip_input_h
+#define included_ip_input_h
+
+#include <vnet/ip/ip.h>
+#include <vnet/ethernet/ethernet.h>
+
+extern char *ip4_error_strings[];
+
+typedef enum
+{
+  IP4_INPUT_NEXT_DROP,
+  IP4_INPUT_NEXT_PUNT,
+  IP4_INPUT_NEXT_LOOKUP,
+  IP4_INPUT_NEXT_LOOKUP_MULTICAST,
+  IP4_INPUT_NEXT_ICMP_ERROR,
+  IP4_INPUT_N_NEXT,
+} ip4_input_next_t;
+
+always_inline void
+ip4_input_check_x2 (vlib_main_t * vm,
+		    vlib_node_runtime_t * error_node,
+		    vlib_buffer_t * p0, vlib_buffer_t * p1,
+		    ip4_header_t * ip0, ip4_header_t * ip1,
+		    u32 * next0, u32 * next1, int verify_checksum)
+{
+  u8 error0, error1;
+  u32 ip_len0, cur_len0;
+  u32 ip_len1, cur_len1;
+  i32 len_diff0, len_diff1;
+
+  error0 = error1 = IP4_ERROR_NONE;
+
+  /* Punt packets with options or wrong version. */
+  if (PREDICT_FALSE (ip0->ip_version_and_header_length != 0x45))
+    error0 = (ip0->ip_version_and_header_length & 0xf) != 5 ?
+      IP4_ERROR_OPTIONS : IP4_ERROR_VERSION;
+
+  if (PREDICT_FALSE (ip1->ip_version_and_header_length != 0x45))
+    error1 = (ip1->ip_version_and_header_length & 0xf) != 5 ?
+      IP4_ERROR_OPTIONS : IP4_ERROR_VERSION;
+
+  if (PREDICT_FALSE (ip0->ttl < 1))
+    error0 = IP4_ERROR_TIME_EXPIRED;
+  if (PREDICT_FALSE (ip1->ttl < 1))
+    error1 = IP4_ERROR_TIME_EXPIRED;
+
+  /* Verify header checksum. */
+  if (verify_checksum)
+    {
+      ip_csum_t sum0, sum1;
+
+      ip4_partial_header_checksum_x1 (ip0, sum0);
+      ip4_partial_header_checksum_x1 (ip1, sum1);
+
+      error0 = 0xffff != ip_csum_fold (sum0) ?
+	IP4_ERROR_BAD_CHECKSUM : error0;
+      error1 = 0xffff != ip_csum_fold (sum1) ?
+	IP4_ERROR_BAD_CHECKSUM : error1;
+    }
+
+  /* Drop fragmentation offset 1 packets. */
+  error0 = ip4_get_fragment_offset (ip0) == 1 ?
+    IP4_ERROR_FRAGMENT_OFFSET_ONE : error0;
+  error1 = ip4_get_fragment_offset (ip1) == 1 ?
+    IP4_ERROR_FRAGMENT_OFFSET_ONE : error1;
+
+  /* Verify lengths. */
+  ip_len0 = clib_net_to_host_u16 (ip0->length);
+  ip_len1 = clib_net_to_host_u16 (ip1->length);
+
+  /* IP length must be at least minimal IP header. */
+  error0 = ip_len0 < sizeof (ip0[0]) ? IP4_ERROR_TOO_SHORT : error0;
+  error1 = ip_len1 < sizeof (ip1[0]) ? IP4_ERROR_TOO_SHORT : error1;
+
+  cur_len0 = vlib_buffer_length_in_chain (vm, p0);
+  cur_len1 = vlib_buffer_length_in_chain (vm, p1);
+
+  len_diff0 = cur_len0 - ip_len0;
+  len_diff1 = cur_len1 - ip_len1;
+
+  error0 = len_diff0 < 0 ? IP4_ERROR_BAD_LENGTH : error0;
+  error1 = len_diff1 < 0 ? IP4_ERROR_BAD_LENGTH : error1;
+
+  if (PREDICT_FALSE (error0 != IP4_ERROR_NONE))
+    {
+      if (error0 == IP4_ERROR_TIME_EXPIRED)
+	{
+	  icmp4_error_set_vnet_buffer (p0, ICMP4_time_exceeded,
+				       ICMP4_time_exceeded_ttl_exceeded_in_transit,
+				       0);
+	  *next0 = IP4_INPUT_NEXT_ICMP_ERROR;
+	}
+      else
+	*next0 = error0 != IP4_ERROR_OPTIONS ?
+	  IP4_INPUT_NEXT_DROP : IP4_INPUT_NEXT_PUNT;
+    }
+  if (PREDICT_FALSE (error1 != IP4_ERROR_NONE))
+    {
+      if (error1 == IP4_ERROR_TIME_EXPIRED)
+	{
+	  icmp4_error_set_vnet_buffer (p1, ICMP4_time_exceeded,
+				       ICMP4_time_exceeded_ttl_exceeded_in_transit,
+				       0);
+	  *next1 = IP4_INPUT_NEXT_ICMP_ERROR;
+	}
+      else
+	*next1 = error1 != IP4_ERROR_OPTIONS ?
+	  IP4_INPUT_NEXT_DROP : IP4_INPUT_NEXT_PUNT;
+    }
+
+  p0->error = error_node->errors[error0];
+  p1->error = error_node->errors[error1];
+}
+
+always_inline void
+ip4_input_check_x1 (vlib_main_t * vm,
+		    vlib_node_runtime_t * error_node,
+		    vlib_buffer_t * p0,
+		    ip4_header_t * ip0, u32 * next0, int verify_checksum)
+{
+  u32 ip_len0, cur_len0;
+  i32 len_diff0;
+  u8 error0;
+
+  error0 = IP4_ERROR_NONE;
+
+  /* Punt packets with options or wrong version. */
+  if (PREDICT_FALSE (ip0->ip_version_and_header_length != 0x45))
+    error0 = (ip0->ip_version_and_header_length & 0xf) != 5 ?
+      IP4_ERROR_OPTIONS : IP4_ERROR_VERSION;
+
+  /* Verify header checksum. */
+  if (verify_checksum)
+    {
+      ip_csum_t sum0;
+
+      ip4_partial_header_checksum_x1 (ip0, sum0);
+
+      error0 = 0xffff != ip_csum_fold (sum0) ?
+	IP4_ERROR_BAD_CHECKSUM : error0;
+    }
+
+  /* Drop fragmentation offset 1 packets. */
+  error0 = ip4_get_fragment_offset (ip0) == 1 ?
+    IP4_ERROR_FRAGMENT_OFFSET_ONE : error0;
+
+  /* Verify lengths. */
+  ip_len0 = clib_net_to_host_u16 (ip0->length);
+
+  /* IP length must be at least minimal IP header. */
+  error0 = ip_len0 < sizeof (ip0[0]) ? IP4_ERROR_TOO_SHORT : error0;
+
+  cur_len0 = vlib_buffer_length_in_chain (vm, p0);
+
+  len_diff0 = cur_len0 - ip_len0;
+
+  error0 = len_diff0 < 0 ? IP4_ERROR_BAD_LENGTH : error0;
+
+  if (PREDICT_FALSE (error0 != IP4_ERROR_NONE))
+    {
+      if (error0 == IP4_ERROR_TIME_EXPIRED)
+	{
+	  icmp4_error_set_vnet_buffer (p0, ICMP4_time_exceeded,
+				       ICMP4_time_exceeded_ttl_exceeded_in_transit,
+				       0);
+	  *next0 = IP4_INPUT_NEXT_ICMP_ERROR;
+	}
+      else
+	*next0 = error0 != IP4_ERROR_OPTIONS ?
+	  IP4_INPUT_NEXT_DROP : IP4_INPUT_NEXT_PUNT;
+    }
+
+  p0->error = error_node->errors[error0];
+}
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
+
+#endif