diff --git a/CHANGELOG b/CHANGELOG
index bb5d8fcb..77da0cff 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -13,9 +13,6 @@ HISTORY
 
   ++ New features:
 
-  2010-05-05: Simon Goldschmidt (Christian Walter)
-  * ip_nat.h/.c, opt.h, ip.c, timers.c: task #7506: added NAT support
-
   2010-05-02: Simon Goldschmidt
   * netbuf.h/.c, sockets.c, api_msg.c: use checksum-on-copy for sending
     UDP data for LWIP_NETIF_TX_SINGLE_PBUF==1
diff --git a/src/core/ipv4/ip.c b/src/core/ipv4/ip.c
index 65d4d942..e780175d 100644
--- a/src/core/ipv4/ip.c
+++ b/src/core/ipv4/ip.c
@@ -43,7 +43,6 @@
 #include "lwip/def.h"
 #include "lwip/mem.h"
 #include "lwip/ip_frag.h"
-#include "lwip/ip_nat.h"
 #include "lwip/inet_chksum.h"
 #include "lwip/netif.h"
 #include "lwip/icmp.h"
@@ -378,30 +377,15 @@ ip_input(struct pbuf *p, struct netif *inp)
 
   /* packet not for us? */
   if (netif == NULL) {
-#if IP_FORWARD || IP_NAT
-    u8_t taken = 0;
-#endif /* IP_FORWARD || IP_NAT */
     /* packet not for us, route or discard */
     LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE, ("ip_input: packet not for us.\n"));
-#if IP_FORWARD || IP_NAT
+#if IP_FORWARD
     /* non-broadcast packet? */
     if (!ip_addr_isbroadcast(&(iphdr->dest), inp)) {
-#if IP_NAT
-      /* check if we want to perform NAT with this packet. */
-      taken = ip_nat_out(p);
-      if (!taken)
-#endif /* IP_NAT */
-      {
-#if IP_FORWARD
-        /* try to forward IP packet on (other) interfaces */
-        if (ip_forward(p, iphdr, inp) != NULL) {
-          taken = 1;
-        }
+      /* try to forward IP packet on (other) interfaces */
+      ip_forward(p, iphdr, inp);
+    } else
 #endif /* IP_FORWARD */
-      }
-    }
-    if (!taken)
-#endif /* IP_FORWARD || IP_NAT */
     {
       snmp_inc_ipinaddrerrors();
       snmp_inc_ipindiscards();
@@ -459,12 +443,6 @@ ip_input(struct pbuf *p, struct netif *inp)
   current_netif = inp;
   current_header = iphdr;
 
-#if IP_NAT
-  if (!ip_addr_isbroadcast(&(iphdr->dest), inp) &&
-      (ip_nat_input(p) != 0)) {
-     LWIP_DEBUGF(IP_DEBUG, ("ip_input: packet consumed by nat layer\n"));
-  } else
-#endif /* IP_NAT */
 #if LWIP_RAW
   /* raw input did not eat the packet? */
   if (raw_input(p, inp) == 0)
diff --git a/src/core/ipv4/ip_nat.c b/src/core/ipv4/ip_nat.c
deleted file mode 100644
index eb291558..00000000
--- a/src/core/ipv4/ip_nat.c
+++ /dev/null
@@ -1,1096 +0,0 @@
-/**
- * NAT - NAT implementation for lwIP supporting TCP/UDP and ICMP.
- * Copyright (c) 2009 Christian Walter, © Embedded Solutions, Vienna 2009.
- *
- * Copyright (c) 2010 lwIP project ;-)
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- * 1. Redistributions of source code must retain the above copyright notice,
- *    this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright notice,
- *    this list of conditions and the following disclaimer in the documentation
- *    and/or other materials provided with the distribution.
- * 3. The name of the author may not be used to endorse or promote products
- *    derived from this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
- * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
- * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
- * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
- * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
- * OF SUCH DAMAGE.
- *
- * This file is part of the lwIP TCP/IP stack.
- */
-
-/*
- * TODOS:
- *  - we should decide if we want to use static tables for NAT or a linked
- *    list.
- *  - we should allocate icmp ping id if multiple clients are sending
- *    ping requests.
- *  - maybe we could hash the identifiers for TCP, ICMP and UDP and use
- *    a single table structure. This would reduce the code amount although
- *    it will cost performance.
- *  - NAT code must check for broadcast addresses and NOT forward
- *    them.
- *
- *  - netif_remove must notify NAT code when a NAT'ed interface is removed
- *  - allocate NAT entries from a new memp pool instead of the heap
- *  - let ttl be ticks, not seconds
- *
- * HOWTO USE:
- *
- * Shows how to create NAT between a PPP interface and an internal NIC.
- * In this case the network 213.129.231.168/29 is nat'ed when packets
- * are sent to the destination network 10.0.0.0/24 (untypical example -
- * most users will have the other way around).
- *
- * Step 1) Execute when network interfaces are ready.
- *
- * new_nat_entry.out_if = (struct netif *)&PPP_IF;
- * new_nat_entry.in_if = (struct netif *)&EMAC_if;
- * IP4_ADDR(&new_nat_entry.source_net, 213, 129, 231, 168);
- * IP4_ADDR(&new_nat_entry.source_netmask, 255, 255, 255, 248);
- * IP4_ADDR(&new_nat_entry.dest_net, 10, 0, 0, 0);
- * IP4_ADDR(&new_nat_entry.source_netmask, 255, 0, 0, 0);
- * ip_nat_add(&new_nat_entry);
- */
-
-#include "lwip/ip_nat.h"
-
-#include "lwip/opt.h"
-
-#if IP_NAT
-
-#include "lwip/ip.h"
-#include "lwip/inet.h"
-#include "lwip/netif.h"
-#include "lwip/ip_addr.h"
-#include "lwip/icmp.h"
-#include "lwip/tcp_impl.h"
-#include "lwip/udp.h"
-#include "lwip/mem.h"
-#include "lwip/sys.h"
-#include "netif/etharp.h"
-
-#include <limits.h>
-#include <string.h>
-
-/** Define this to enable debug output of this module */
-#ifndef LWIP_NAT_DEBUG
-#define LWIP_NAT_DEBUG LWIP_DBG_OFF
-#endif
-
-
-#define LWIP_NAT_TTL_INFINITE                    (INT_MAX)
-#define LWIP_NAT_DEFAULT_TTL_SECONDS             (60)
-#define LWIP_NAT_FORWARD_HEADER_SIZE_MIN         (sizeof(struct eth_hdr))
-#define LWIP_NAT_DEFAULT_STATE_TABLES_ICMP       (2)
-#define LWIP_NAT_DEFAULT_STATE_TABLES_TCP        (16)
-#define LWIP_NAT_DEFAULT_STATE_TABLES_UDP        (16)
-
-#define LWIP_NAT_DEFAULT_TCP_SOURCE_PORT         (40000)
-#define LWIP_NAT_DEFAULT_UDP_SOURCE_PORT         (40000)
-
-#define IPNAT_ENTRY_RESET(x) do { \
-  (x)->ttl = 0; \
-} while(0)
-
-typedef struct ip_nat_conf
-{
-  struct ip_nat_conf *next;
-  ip_nat_entry_t      entry;
-} ip_nat_conf_t;
-
-typedef struct ip_nat_entry_common
-{
-  s32_t           ttl; /* @todo: do we really need this to be signed?? */
-  ip_addr_t       source;
-  ip_addr_t       dest;
-  ip_nat_conf_t   *cfg;
-} ip_nat_entry_common_t;
-
-typedef struct ip_nat_entries_icmp
-{
-  ip_nat_entry_common_t common;
-  u16_t                 id;
-  u16_t                 seqno;
-} ip_nat_entries_icmp_t;
-
-typedef struct ip_nat_entries_tcp
-{
-  ip_nat_entry_common_t common;
-  u16_t                 nport;
-  u16_t                 sport;
-  u16_t                 dport;
-} ip_nat_entries_tcp_t;
-
-typedef struct ip_nat_entries_udp
-{
-  ip_nat_entry_common_t common;
-  u16_t                 nport;
-  u16_t                 sport;
-  u16_t                 dport;
-} ip_nat_entries_udp_t;
-
-typedef union u_nat_entry
-{
-  ip_nat_entry_common_t *cmn;
-  ip_nat_entries_tcp_t  *tcp;
-  ip_nat_entries_icmp_t *icmp;
-  ip_nat_entries_udp_t  *udp;
-} nat_entry_t;
-
-
-static ip_nat_conf_t *ip_nat_cfg = NULL;
-static ip_nat_entries_icmp_t ip_nat_icmp_table[LWIP_NAT_DEFAULT_STATE_TABLES_ICMP];
-static ip_nat_entries_tcp_t ip_nat_tcp_table[LWIP_NAT_DEFAULT_STATE_TABLES_TCP];
-static ip_nat_entries_udp_t ip_nat_udp_table[LWIP_NAT_DEFAULT_STATE_TABLES_UDP];
-
-/* ----------------------- Static functions (COMMON) --------------------*/
-static void     ip_nat_chksum_adjust(u8_t *chksum, const u8_t *optr, s16_t olen, const u8_t *nptr, s16_t nlen);
-static void     ip_nat_cmn_init(ip_nat_conf_t *nat_config, const struct ip_hdr *iphdr,
-                                 ip_nat_entry_common_t *nat_entry);
-static ip_nat_conf_t *ip_nat_shallnat(const struct ip_hdr *iphdr);
-static void     ip_nat_reset_state(ip_nat_conf_t *cfg);
-
-/* ----------------------- Static functions (DEBUG) ---------------------*/
-#if defined(LWIP_DEBUG) && (LWIP_NAT_DEBUG & LWIP_DBG_ON)
-static void     ip_nat_dbg_dump(const char *msg, const struct ip_hdr *iphdr);
-static void     ip_nat_dbg_dump_ip(const ip_addr_t *addr);
-static void     ip_nat_dbg_dump_icmp_nat_entry(const char *msg, const ip_nat_entries_icmp_t *nat_entry);
-static void     ip_nat_dbg_dump_tcp_nat_entry(const char *msg, const ip_nat_entries_tcp_t *nat_entry);
-static void     ip_nat_dbg_dump_udp_nat_entry(const char *msg, const ip_nat_entries_udp_t *nat_entry);
-static void     ip_nat_dbg_dump_init(ip_nat_conf_t *ip_nat_cfg_new);
-static void     ip_nat_dbg_dump_remove(ip_nat_conf_t *cur);
-#else /* defined(LWIP_DEBUG) && (LWIP_NAT_DEBUG & LWIP_DBG_ON) */
-#define ip_nat_dbg_dump(msg, iphdr)
-#define ip_nat_dbg_dump_ip(addr)
-#define ip_nat_dbg_dump_icmp_nat_entry(msg, nat_entry)
-#define ip_nat_dbg_dump_tcp_nat_entry(msg, nat_entry)
-#define ip_nat_dbg_dump_udp_nat_entry(msg, nat_entry)
-#define ip_nat_dbg_dump_init(ip_nat_cfg_new)
-#define ip_nat_dbg_dump_remove(cur)
-#endif /* defined(LWIP_DEBUG) && (LWIP_NAT_DEBUG & LWIP_DBG_ON) */
-
-/* ----------------------- Static functions (TCP) -----------------------*/
-static ip_nat_entries_tcp_t *ip_nat_tcp_lookup_incoming(const struct ip_hdr *iphdr, const struct tcp_hdr *tcphdr);
-static ip_nat_entries_tcp_t *ip_nat_tcp_lookup_outgoing(ip_nat_conf_t *nat_config,
-                                                         const struct ip_hdr *iphdr, const struct tcp_hdr *tcphdr,
-                                                         u8_t allocate);
-
-/* ----------------------- Static functions (UDP) -----------------------*/
-static ip_nat_entries_udp_t *ip_nat_udp_lookup_incoming(const struct ip_hdr *iphdr, const struct udp_hdr *udphdr);
-static ip_nat_entries_udp_t *ip_nat_udp_lookup_outgoing(ip_nat_conf_t *nat_config,
-                                                         const struct ip_hdr *iphdr, const struct udp_hdr *udphdr,
-                                                         u8_t allocate);
-
-/** Initialize this module */
-void
-ip_nat_init(void)
-{
-  int i;
-
-  /* @todo: this can be omitted since we trust static variables
-            to be initialized to zero */
-  for (i = 0; i < LWIP_NAT_DEFAULT_STATE_TABLES_ICMP; i++) {
-    IPNAT_ENTRY_RESET(&ip_nat_icmp_table[i].common);
-  }
-  for (i = 0; i < LWIP_NAT_DEFAULT_STATE_TABLES_TCP; i++) {
-    IPNAT_ENTRY_RESET(&ip_nat_tcp_table[i].common);
-  }
-  for (i = 0; i < LWIP_NAT_DEFAULT_STATE_TABLES_UDP; i++) {
-    IPNAT_ENTRY_RESET(&ip_nat_udp_table[i].common);
-  }
-}
-
-/** Allocate a new ip_nat_conf_t item */
-static ip_nat_conf_t*
-ip_nat_alloc(void)
-{
-  ip_nat_conf_t *ret = (ip_nat_conf_t*)mem_malloc(sizeof(ip_nat_conf_t));
-  return ret;
-}
-
-/** Free a removed ip_nat_conf_t item */
-static void
-ip_nat_free(ip_nat_conf_t *item)
-{
-  LWIP_ASSERT("item != NULL", item != NULL);
-  mem_free(item);
-}
-
-/** Add a new NAT entry
- *
- * @param new_entry pointer to a structure used to initialize the entry
- * @return ERR_OK if succeeded
- */
-err_t
-ip_nat_add(const ip_nat_entry_t *new_entry)
-{
-  err_t err = ERR_VAL;
-  ip_nat_conf_t *cur = ip_nat_cfg;
-  ip_nat_conf_t *ip_nat_cfg_new = ip_nat_alloc();
-  LWIP_ASSERT("new_entry != NULL", new_entry != NULL);
-
-  if (ip_nat_cfg_new != NULL) {
-    SMEMCPY(&ip_nat_cfg_new->entry, new_entry, sizeof(ip_nat_entry_t));
-    ip_nat_cfg_new->next = NULL;
-
-    ip_nat_dbg_dump_init(ip_nat_cfg_new);
-
-    if (ip_nat_cfg == NULL) {
-      ip_nat_cfg = ip_nat_cfg_new;
-    } else {
-      /* @todo: do we really need to enqueue the new entry at the end?? */
-      while (cur->next != NULL) {
-        cur = cur->next;
-      }
-      cur->next = ip_nat_cfg_new;
-    }
-    err = ERR_OK;
-  } else {
-    err = ERR_MEM;
-  }
-  return err;
-}
-
-/** Remove a NAT entry previously added by 'ip_nat_add()'.
- *
- * @param remove_entry describes the entry to remove
- */
-void
-ip_nat_remove(const ip_nat_entry_t *remove_entry)
-{
-  ip_nat_conf_t *cur = ip_nat_cfg;
-  ip_nat_conf_t *next;
-  ip_nat_conf_t *previous = NULL;
-
-  while (cur != NULL) {
-    /* Remove the NAT interfaces */
-    if ((cur->entry.source_net.addr     == remove_entry->source_net.addr) &&
-        (cur->entry.source_netmask.addr == remove_entry->source_netmask.addr) &&
-        (cur->entry.dest_net.addr       == remove_entry->dest_net.addr) &&
-        (cur->entry.dest_netmask.addr   == remove_entry->dest_netmask.addr) &&
-        (cur->entry.out_if              == remove_entry->out_if) &&
-        (cur->entry.in_if               == remove_entry->in_if))
-    {
-      ip_nat_dbg_dump_remove(cur);
-
-      ip_nat_reset_state(cur);
-      next = cur->next;
-      if (cur == ip_nat_cfg) {
-        ip_nat_cfg = next;
-      } else {
-        LWIP_ASSERT("NULL != previous", NULL != previous);
-        previous->next = next;
-      }
-      /* free 'cur' or there will be a memory leak */
-      ip_nat_free(cur);
-      return;
-    } else {
-      previous = cur;
-      cur = cur->next;
-    }
-  }
-}
-
-/** Reset a NAT configured entry to be reused.
- * Effectively calls IPNAT_ENTRY_RESET() on 'cfg'.
- *
- * @param cfg NAT entry to reset
- */
-static void
-ip_nat_reset_state(ip_nat_conf_t *cfg)
-{
-  int i;
-
-  /* @todo: optimize this!!! 
-     why do we search for it anyway, if we have the pointer??? */
-  for (i = 0; i < LWIP_NAT_DEFAULT_STATE_TABLES_ICMP; i++) {
-    if(ip_nat_icmp_table[i].common.cfg == cfg) {
-      IPNAT_ENTRY_RESET(&ip_nat_icmp_table[i].common);
-    }
-  }
-  for (i = 0; i < LWIP_NAT_DEFAULT_STATE_TABLES_TCP; i++) {
-    if(ip_nat_icmp_table[i].common.cfg == cfg) {
-      IPNAT_ENTRY_RESET(&ip_nat_tcp_table[i].common);
-    }
-  }
-  for (i = 0; i < LWIP_NAT_DEFAULT_STATE_TABLES_UDP; i++) {
-    if(ip_nat_icmp_table[i].common.cfg == cfg) {
-      IPNAT_ENTRY_RESET(&ip_nat_udp_table[i].common);
-    }
-  }
-}
-
-/** Check if this packet should be routed or should be translated
- *
- * @param iphdr the IP header to check
- * @return - a NAT entry if the packet shall be translated,
- *         - NULL if the packet shall be routed normally
- */
-static ip_nat_conf_t *
-ip_nat_shallnat(const struct ip_hdr *iphdr)
-{
-  ip_nat_conf_t *nat_config;
-
-  for (nat_config = ip_nat_cfg; nat_config != NULL; nat_config = nat_config->next) {
-    if (ip_addr_netcmp(&(iphdr->dest), &(nat_config->entry.dest_net),
-                       &(nat_config->entry.dest_netmask)) &&
-      ip_addr_netcmp(&(iphdr->src), &(nat_config->entry.source_net),
-                     &(nat_config->entry.source_netmask))) {
-        break;
-    }
-  }
-
-  return nat_config;
-}
-
-/** Check if the IP header can be hidden and if the remaining packet
- * is long enough. p->payload is reset to the IP header on return.
- *
- * @param p received packet, p->payload pointing to IP header
- * @param min_size minimum p->tot_len after hiding IP header
- * @return a pointer to the next header (after IP header),
- *         NULL if hiding IP header fails or the packet is too short
- */
-static void*
-ip_nat_check_header(struct pbuf *p, u16_t min_size)
-{
-  void *ret = NULL;
-  struct ip_hdr  *iphdr = (struct ip_hdr*)p->payload;
-  s16_t iphdr_len = IPH_HL(iphdr) * 4;
-
-  if(!pbuf_header(p, -iphdr_len)) {
-    if(p->tot_len >= min_size) {
-      ret = p->payload;
-    }
-    /* Restore pbuf payload pointer from previous header check. */
-    pbuf_header(p, iphdr_len);
-  }
-  return ret;
-}
-
-/** Input processing: check if a received packet belongs to a NAT entry
- * and if so, translated it and send it on.
- *
- * @param p received packet
- * @return 1 if the packet has been consumed (it was a NAT packet),
- *         0 if the packet has not been consumed (no NAT packet)
- */
-u8_t
-ip_nat_input(struct pbuf *p)
-{
-  struct ip_hdr        *iphdr = (struct ip_hdr*)p->payload;
-  struct tcp_hdr       *tcphdr;
-  struct udp_hdr       *udphdr;
-  struct icmp_echo_hdr *icmphdr;
-  nat_entry_t           nat_entry;
-  err_t                 err;
-  u8_t                  consumed = 0;
-  int                   i;
-  struct pbuf          *q = NULL;
-
-  nat_entry.cmn = NULL;
-  ip_nat_dbg_dump("ip_nat_in: checking nat for", iphdr);
-
-  switch (IPH_PROTO(iphdr)) {
-    case IP_PROTO_TCP:
-      tcphdr = (struct tcp_hdr*)ip_nat_check_header(p, sizeof(struct tcp_hdr));
-      if (tcphdr == NULL) {
-        LWIP_DEBUGF(LWIP_NAT_DEBUG, ("ip_nat_input: short tcp packet (%" U16_F " bytes) discarded\n", p->tot_len));
-      } else {
-        nat_entry.tcp = ip_nat_tcp_lookup_incoming(iphdr, tcphdr);
-        if (nat_entry.tcp != NULL) {
-          /* Refresh TCP entry */
-          nat_entry.tcp->common.ttl = LWIP_NAT_DEFAULT_TTL_SECONDS;
-          tcphdr->dest = nat_entry.tcp->sport;
-          /* Adjust TCP checksum for changed destination port */
-          ip_nat_chksum_adjust((u8_t *)&(tcphdr->chksum),
-            (u8_t *)&(nat_entry.tcp->nport), 2, (u8_t *)&(tcphdr->dest), 2);
-          /* Adjust TCP checksum for changing dest IP address */
-          ip_nat_chksum_adjust((u8_t *)&(tcphdr->chksum),
-            (u8_t *)&(nat_entry.cmn->cfg->entry.out_if->ip_addr.addr), 4,
-            (u8_t *)&(nat_entry.cmn->source.addr), 4);
-
-          consumed = 1;
-        }
-      }
-      break;
-
-    case IP_PROTO_UDP:
-      udphdr = (struct udp_hdr *)ip_nat_check_header(p, sizeof(struct udp_hdr));
-      if (udphdr == NULL) {
-        LWIP_DEBUGF(LWIP_NAT_DEBUG,
-          ("ip_nat_input: short udp packet (%" U16_F " bytes) discarded\n",
-          p->tot_len));
-      } else {
-        nat_entry.udp = ip_nat_udp_lookup_incoming(iphdr, udphdr);
-        if (nat_entry.udp != NULL) {
-          /* Refresh UDP entry */
-          nat_entry.udp->common.ttl = LWIP_NAT_DEFAULT_TTL_SECONDS;
-          udphdr->dest = nat_entry.udp->sport;
-          /* Adjust UDP checksum for changed destination port */
-          ip_nat_chksum_adjust((u8_t *)&(udphdr->chksum),
-            (u8_t *)&(nat_entry.udp->nport), 2, (u8_t *)&(udphdr->dest), 2);
-          /* Adjust UDP checksum for changing dest IP address */
-          ip_nat_chksum_adjust((u8_t *)&(udphdr->chksum),
-            (u8_t *)&(nat_entry.cmn->cfg->entry.out_if->ip_addr.addr), 4,
-            (u8_t *)&(nat_entry.cmn->source.addr), 4);
-
-          consumed = 1;
-        }
-      }
-      break;
-
-    case IP_PROTO_ICMP:
-      icmphdr = (struct icmp_echo_hdr *)ip_nat_check_header(p, sizeof(struct icmp_echo_hdr));
-      if (icmphdr == NULL) {
-        LWIP_DEBUGF(LWIP_NAT_DEBUG,
-          ("ip_nat_out: short icmp echo reply packet (%" U16_F " bytes) discarded\n",
-          p->tot_len));
-      } else {
-        if (ICMP_ER == ICMPH_TYPE(icmphdr)) {
-          for (i = 0; i < LWIP_NAT_DEFAULT_STATE_TABLES_ICMP; i++) {
-            nat_entry.icmp = &ip_nat_icmp_table[i];
-            if ((nat_entry.icmp->common.ttl) &&
-                (iphdr->src.addr == nat_entry.icmp->common.dest.addr) &&
-                (nat_entry.icmp->id == icmphdr->id) &&
-                (nat_entry.icmp->seqno == icmphdr->seqno)) {
-              ip_nat_dbg_dump_icmp_nat_entry("found existing nat entry: ", nat_entry.icmp);
-              consumed = 1;
-              IPNAT_ENTRY_RESET(nat_entry.cmn);
-              break;
-            }
-          }
-        }
-      }
-      break;
-
-    default:
-      break;
-  }
-
-  if(consumed) {
-    /* packet consumed, send it out on in_if */
-    struct netif *in_if;
-
-    /* check if the pbuf has room for link headers */
-    if (pbuf_header(p, PBUF_LINK_HLEN)) {
-      /* pbuf has no room for link headers, allocate an extra pbuf */
-      q = pbuf_alloc(PBUF_LINK, 0, PBUF_RAM);
-      if (q == NULL) {
-        LWIP_DEBUGF(LWIP_NAT_DEBUG, ("ip_nat_input: no pbuf for outgoing header\n"));
-        /* @todo: stats? */
-        pbuf_free(p);
-        p = NULL;
-        return 1;
-      } else {
-        pbuf_cat(q, p);
-      }
-    } else {
-      /* restore p->payload to IP header */
-      if (pbuf_header(p, -PBUF_LINK_HLEN)) {
-        LWIP_DEBUGF(LWIP_NAT_DEBUG, ("ip_nat_input: restoring header failed\n"));
-        /* @todo: stats? */
-        pbuf_free(p);
-        p = NULL;
-        return 1;
-      }
-    }
-    /* if we come here, q is the pbuf to send (either points to p or to a chain) */
-    in_if = nat_entry.cmn->cfg->entry.in_if;
-    iphdr->dest.addr = nat_entry.cmn->source.addr;
-    ip_nat_chksum_adjust((u8_t *) & IPH_CHKSUM(iphdr),
-      (u8_t *) & (nat_entry.cmn->cfg->entry.out_if->ip_addr.addr), 4,
-      (u8_t *) & (iphdr->dest.addr), 4);
-
-    ip_nat_dbg_dump("ip_nat_input: packet back to source after nat: ", iphdr);
-    LWIP_DEBUGF(LWIP_NAT_DEBUG, ("ip_nat_input: sending packet on interface ("));
-    ip_nat_dbg_dump_ip(&(in_if->ip_addr));
-    LWIP_DEBUGF(LWIP_NAT_DEBUG, (")\n"));
-
-    err = in_if->output(in_if, q, &(iphdr->dest));
-    if(err != ERR_OK) {
-      LWIP_DEBUGF(LWIP_NAT_DEBUG,
-        ("ip_nat_input: failed to send rewritten packet. link layer returned %d\n",
-        err));
-    }
-    /* now that q (and/or p) is sent (or not), give up the reference to it
-       this frees the input pbuf (p) as we have consumed it. */
-    pbuf_free(q);
-  }
-  return consumed;
-}
-
-/** Check if one NAT entry timed out */
-static void
-ip_nat_check_timeout(ip_nat_entry_common_t *nat_entry)
-{
-  if(nat_entry->ttl > 0) {
-    if(nat_entry->ttl != LWIP_NAT_TTL_INFINITE) {
-      /* this is not a 'no-timeout' entry */
-      if(nat_entry->ttl > LWIP_NAT_TMR_INTERVAL_SEC) {
-        nat_entry->ttl -= LWIP_NAT_TMR_INTERVAL_SEC;
-      } else {
-        nat_entry->ttl = 0;
-      }
-    }
-  }
-}
-
-/** The NAT timer function, to be called at an interval of
- * LWIP_NAT_TMR_INTERVAL_SEC seconds.
- */
-void
-ip_nat_tmr(void)
-{
-  int i;
-
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, ("ip_nat_tmr: removing old entries\n"));
-
-  for(i = 0; i < LWIP_NAT_DEFAULT_STATE_TABLES_ICMP; i++) {
-    ip_nat_check_timeout((ip_nat_entry_common_t *) & ip_nat_icmp_table[i]);
-  }
-  for(i = 0; i < LWIP_NAT_DEFAULT_STATE_TABLES_TCP; i++) {
-    ip_nat_check_timeout((ip_nat_entry_common_t *) & ip_nat_tcp_table[i]);
-  }
-  for(i = 0; i < LWIP_NAT_DEFAULT_STATE_TABLES_UDP; i++) {
-    ip_nat_check_timeout((ip_nat_entry_common_t *) & ip_nat_udp_table[i]);
-  }
-}
-
-/** Vheck if we want to perform NAT with this packet. If so, send it out on
- * the correct interface.
- *
- * @param p the packet to test/send
- * @return 1: the packet has been sent using NAT,
- *         0: the packet did not belong to a NAT entry
- */
-u8_t
-ip_nat_out(struct pbuf *p)
-{
-  u8_t                  sent = 0;
-  err_t                 err;
-  struct ip_hdr        *iphdr = p->payload;
-  struct icmp_echo_hdr *icmphdr;
-  struct tcp_hdr       *tcphdr;
-  struct udp_hdr       *udphdr;
-  ip_nat_conf_t        *nat_config;
-  nat_entry_t           nat_entry;
-  int             i;
-
-  nat_entry.cmn = NULL;
-
-  ip_nat_dbg_dump("ip_nat_out: checking nat for", iphdr);
-
-  /* Check if this packet should be routed or should be translated */
-  nat_config = ip_nat_shallnat(iphdr);
-  if (nat_config != NULL ) {
-    if (nat_config->entry.out_if == NULL) {
-      LWIP_DEBUGF(LWIP_NAT_DEBUG, ("ip_nat_out: no external interface for nat table entry\n"));
-    } else {
-      switch (IPH_PROTO(iphdr))
-      {
-      case IP_PROTO_TCP:
-        tcphdr = (struct tcp_hdr *)ip_nat_check_header(p, sizeof(struct tcp_hdr));
-        if (tcphdr == NULL) {
-          LWIP_DEBUGF(LWIP_NAT_DEBUG,
-            ("ip_nat_out: short tcp packet (%" U16_F " bytes) discarded\n", p->tot_len));
-        } else {
-          nat_entry.tcp = ip_nat_tcp_lookup_outgoing(nat_config, iphdr, tcphdr, 1);
-          if (nat_entry.tcp != NULL) {
-            /* Adjust TCP checksum for changing source port */
-            tcphdr->src = nat_entry.tcp->nport;
-            ip_nat_chksum_adjust((u8_t *)&(tcphdr->chksum),
-              (u8_t *)&(nat_entry.tcp->sport), 2, (u8_t *)&(tcphdr->src), 2);
-            /* Adjust TCP checksum for changing source IP address */
-            ip_nat_chksum_adjust((u8_t *)&(tcphdr->chksum),
-              (u8_t *)&(nat_entry.cmn->source.addr), 4,
-              (u8_t *)&(nat_entry.cmn->cfg->entry.out_if->ip_addr.addr), 4);
-          }
-        }
-        break;
-
-      case IP_PROTO_UDP:
-        udphdr = (struct udp_hdr *)ip_nat_check_header(p, sizeof(struct udp_hdr));
-        if (udphdr == NULL) {
-          LWIP_DEBUGF(LWIP_NAT_DEBUG,
-            ("ip_nat_out: short udp packet (%" U16_F " bytes) discarded\n", p->tot_len));
-        } else {
-          nat_entry.udp = ip_nat_udp_lookup_outgoing(nat_config, iphdr, udphdr, 1);
-          if (nat_entry.udp != NULL) {
-            /* Adjust UDP checksum for changing source port */
-            udphdr->src = nat_entry.udp->nport;
-            ip_nat_chksum_adjust((u8_t *)&(udphdr->chksum),
-              (u8_t *)&(nat_entry.udp->sport), 2, (u8_t *) & (udphdr->src), 2);
-            /* Adjust UDP checksum for changing source IP address */
-            ip_nat_chksum_adjust((u8_t *)&(udphdr->chksum),
-              (u8_t *)&(nat_entry.cmn->source.addr), 4,
-              (u8_t *)&(nat_entry.cmn->cfg->entry.out_if->ip_addr.addr), 4);
-          }
-        }
-        break;
-
-      case IP_PROTO_ICMP:
-        icmphdr = (struct icmp_echo_hdr *)ip_nat_check_header(p, sizeof(struct icmp_echo_hdr));
-        if(icmphdr == NULL) {
-          LWIP_DEBUGF(LWIP_NAT_DEBUG,
-            ("ip_nat_out: short icmp echo packet (%" U16_F " bytes) discarded\n", p->tot_len));
-        } else {
-          if (ICMPH_TYPE(icmphdr) == ICMP_ECHO) {
-            for (i = 0; i < LWIP_NAT_DEFAULT_STATE_TABLES_ICMP; i++) {
-              if (!ip_nat_icmp_table[i].common.ttl) {
-                nat_entry.icmp = &ip_nat_icmp_table[i];
-                ip_nat_cmn_init(nat_config, iphdr, nat_entry.cmn);
-                nat_entry.icmp->id = icmphdr->id;
-                nat_entry.icmp->seqno = icmphdr->seqno;
-                ip_nat_dbg_dump_icmp_nat_entry(" ip_nat_out: created new NAT entry ", nat_entry.icmp);
-                break;
-              }
-            }
-            if (NULL == nat_entry.icmp)
-            {
-              LWIP_DEBUGF(LWIP_NAT_DEBUG, ("ip_nat_out: no more NAT entries for ICMP available\n"));
-            }
-          }
-        }
-        break;
-      default:
-        break;
-      }
-
-      if (nat_entry.cmn != NULL) {
-        struct netif *out_if = nat_entry.cmn->cfg->entry.out_if;
-        /* Exchange the IP source address with the address of the interface
-        * where the packet will be sent.
-        */
-        /* @todo: check nat_config->entry.out_if agains nat_entry.cmn->cfg->entry.out_if */
-        iphdr->src.addr = nat_config->entry.out_if->ip_addr.addr;
-        ip_nat_chksum_adjust((u8_t *) & IPH_CHKSUM(iphdr),
-          (u8_t *) & (nat_entry.cmn->source.addr), 4, (u8_t *) & iphdr->src.addr, 4);
-
-        ip_nat_dbg_dump("ip_nat_out: rewritten packet", iphdr);
-        LWIP_DEBUGF(LWIP_NAT_DEBUG, ("ip_nat_out: sending packet on interface ("));
-        ip_nat_dbg_dump_ip(&(out_if->ip_addr));
-        LWIP_DEBUGF(LWIP_NAT_DEBUG, (")\n"));
-
-        err = out_if->output(out_if, p, &(iphdr->dest));
-        if (err != ERR_OK) {
-          LWIP_DEBUGF(LWIP_NAT_DEBUG,
-            ("ip_nat_out: failed to send rewritten packet. link layer returned %d\n", err));
-        } else {
-          sent = 1;
-        }
-      }
-    }
-  }
-
-  return sent;
-}
-
-/** Initialize common parts of a NAT entry
- *
- * @param nat_config NAT config entry
- * @param iphdr IP header from which to initialize the entry
- * @param nat_entry entry to initialize
- */
-static void
-ip_nat_cmn_init(ip_nat_conf_t *nat_config, const struct ip_hdr *iphdr, ip_nat_entry_common_t *nat_entry)
-{
-  LWIP_ASSERT("NULL != nat_entry", NULL != nat_entry);
-  LWIP_ASSERT("NULL != nat_config", NULL != nat_config);
-  LWIP_ASSERT("NULL != iphdr", NULL != iphdr);
-  nat_entry->cfg = nat_config;
-  nat_entry->dest = iphdr->dest;
-  nat_entry->source = iphdr->src;
-  nat_entry->ttl = LWIP_NAT_DEFAULT_TTL_SECONDS;
-}
-
-/**
- * This function checks for incoming packets if we already have a NAT entry.
- * If yes a pointer to the NAT entry is returned. Otherwise NULL.
- *
- * @param nat_config NAT configuration.
- * @param iphdr The IP header.
- * @param udphdr The UDP header.
- * @return A pointer to an existing NAT entry or
- *         NULL if none is found.
- */
-static ip_nat_entries_udp_t *
-ip_nat_udp_lookup_incoming(const struct ip_hdr *iphdr, const struct udp_hdr *udphdr)
-{
-  int i;
-  ip_nat_entries_udp_t *nat_entry = NULL;
-
-  for (i = 0; i < LWIP_NAT_DEFAULT_STATE_TABLES_UDP; i++) {
-    if (ip_nat_udp_table[i].common.ttl) {
-      if ((iphdr->src.addr == ip_nat_udp_table[i].common.dest.addr) &&
-          (udphdr->src == ip_nat_udp_table[i].dport) &&
-          (udphdr->dest == ip_nat_udp_table[i].nport)) {
-        nat_entry = &ip_nat_udp_table[i];
-        ip_nat_dbg_dump_udp_nat_entry("ip_nat_udp_lookup_incoming: found existing nat entry: ",
-                                      nat_entry);
-        break;
-      }
-    }
-  }
-  return nat_entry;
-}
-
-/**
- * This function checks if we already have a NAT entry for this UDP connection.
- * If yes the a pointer to this NAT entry is returned.
- *
- * @param iphdr The IP header.
- * @param udphdr The UDP header.
- * @param allocate If no existing NAT entry is found and this flag is true
- *        a NAT entry is allocated.
- */
-static ip_nat_entries_udp_t *
-ip_nat_udp_lookup_outgoing(ip_nat_conf_t *nat_config, const struct ip_hdr *iphdr,
-                           const struct udp_hdr *udphdr, u8_t allocate)
-{
-  int i;
-  nat_entry_t nat_entry;
-  int last_free = -1;
-
-  nat_entry.cmn = NULL;
-  for (i = 0; i < LWIP_NAT_DEFAULT_STATE_TABLES_UDP; i++) {
-    if (ip_nat_udp_table[i].common.ttl) {
-      if ((iphdr->src.addr == ip_nat_udp_table[i].common.source.addr) &&
-          (iphdr->dest.addr == ip_nat_udp_table[i].common.dest.addr) &&
-          (udphdr->src == ip_nat_udp_table[i].sport) &&
-          (udphdr->dest == ip_nat_udp_table[i].dport)) {
-        nat_entry.udp = &ip_nat_udp_table[i];
-
-        ip_nat_dbg_dump_udp_nat_entry("ip_nat_udp_lookup_outgoing: found existing nat entry: ",
-                                      nat_entry.udp);
-      }
-    } else {
-      last_free = i;
-    }
-  }
-  if (nat_entry.cmn == NULL) {
-    if (allocate) {
-      if (last_free != -1) {
-        nat_entry.udp = &ip_nat_udp_table[last_free];
-        nat_entry.udp->nport = htons((u16_t) (LWIP_NAT_DEFAULT_UDP_SOURCE_PORT + i));
-        nat_entry.udp->sport = udphdr->src;
-        nat_entry.udp->dport = udphdr->dest;
-        ip_nat_cmn_init(nat_config, iphdr, nat_entry.cmn);
-
-        ip_nat_dbg_dump_udp_nat_entry("ip_nat_udp_lookup_outgoing: created new nat entry: ",
-                                      nat_entry.udp);
-      } else {
-        LWIP_DEBUGF(LWIP_NAT_DEBUG, ("ip_nat_udp_lookup_outgoing: no more NAT entries available\n"));
-      }
-    }
-  }
-  return nat_entry.udp;
-}
-
-/**
- * This function checks for incoming packets if we already have a NAT entry.
- * If yes a pointer to the NAT entry is returned. Otherwise NULL.
- *
- * @param nat_config NAT configuration.
- * @param iphdr The IP header.
- * @param tcphdr The TCP header.
- * @return A pointer to an existing NAT entry or NULL if none is found.
- */
-static ip_nat_entries_tcp_t *
-ip_nat_tcp_lookup_incoming(const struct ip_hdr *iphdr, const struct tcp_hdr *tcphdr)
-{
-  int i;
-  ip_nat_entries_tcp_t *nat_entry = NULL;
-
-  for (i = 0; i < LWIP_NAT_DEFAULT_STATE_TABLES_TCP; i++) {
-    if (ip_nat_tcp_table[i].common.ttl) {
-      if ((iphdr->src.addr == ip_nat_tcp_table[i].common.dest.addr) &&
-          (tcphdr->src == ip_nat_tcp_table[i].dport) &&
-          (tcphdr->dest == ip_nat_tcp_table[i].nport)) {
-        nat_entry = &ip_nat_tcp_table[i];
-
-        ip_nat_dbg_dump_tcp_nat_entry("ip_nat_tcp_lookup_incoming: found existing nat entry: ",
-                                      nat_entry);
-        break;
-      }
-    }
-  }
-  return nat_entry;
-}
-
-/**
- * This function checks if we already have a NAT entry for this TCP connection.
- * If yes the a pointer to this NAT entry is returned.
- *
- * @param iphdr The IP header.
- * @param tcphdr The TCP header.
- * @param allocate If no existing NAT entry is found and this flag is true
- *   a NAT entry is allocated.
- */
-static ip_nat_entries_tcp_t *
-ip_nat_tcp_lookup_outgoing(ip_nat_conf_t *nat_config, const struct ip_hdr *iphdr,
-                           const struct tcp_hdr *tcphdr, u8_t allocate)
-{
-  int i;
-  nat_entry_t nat_entry;
-  int last_free = -1;
-
-  nat_entry.cmn = NULL;
-  for (i = 0; i < LWIP_NAT_DEFAULT_STATE_TABLES_TCP; i++) {
-    if (ip_nat_tcp_table[i].common.ttl) {
-      if ((iphdr->src.addr == ip_nat_tcp_table[i].common.source.addr) &&
-          (iphdr->dest.addr == ip_nat_tcp_table[i].common.dest.addr) &&
-          (tcphdr->src == ip_nat_tcp_table[i].sport) &&
-          (tcphdr->dest == ip_nat_tcp_table[i].dport)) {
-        nat_entry.tcp = &ip_nat_tcp_table[i];
-
-        ip_nat_dbg_dump_tcp_nat_entry("ip_nat_tcp_lookup_outgoing: found existing nat entry: ",
-                                      nat_entry.tcp);
-      }
-    } else {
-      last_free = i;
-    }
-  }
-  if (nat_entry.cmn == NULL) {
-    if (allocate) {
-      if (last_free != -1) {
-        nat_entry.tcp = &ip_nat_tcp_table[last_free];
-        nat_entry.tcp->nport = htons((u16_t) (LWIP_NAT_DEFAULT_TCP_SOURCE_PORT + i));
-        nat_entry.tcp->sport = tcphdr->src;
-        nat_entry.tcp->dport = tcphdr->dest;
-        ip_nat_cmn_init(nat_config, iphdr, nat_entry.cmn);
-
-        ip_nat_dbg_dump_tcp_nat_entry("ip_nat_tcp_lookup_outgoing: created new nat entry: ",
-                                      nat_entry.tcp);
-      } else {
-        LWIP_DEBUGF(LWIP_NAT_DEBUG, ("ip_nat_udp_lookup_outgoing: no more NAT entries available\n"));
-      }
-    }
-  }
-  return nat_entry.tcp;
-}
-
-/** Adjusts the checksum of a NAT'ed packet without having to completely recalculate it
- * @todo: verify this works for little- and big-endian
- *
- * @param chksum points to the chksum in the packet
- * @param optr points to the old data in the packet
- * @param olen length of old data
- * @param nptr points to the new data in the packet
- * @param nlen length of new data
- */
-static void
-ip_nat_chksum_adjust(u8_t *chksum, const u8_t *optr, s16_t olen, const u8_t *nptr, s16_t nlen)
-{
-  s32_t x, oldval, newval;
-
-  LWIP_ASSERT("NULL != chksum", NULL != chksum);
-  LWIP_ASSERT("NULL != optr", NULL != optr);
-  LWIP_ASSERT("NULL != nptr", NULL != nptr);
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, ("ip_nat_chksum_adjust: chksum=%p, optr=%p, olen=%" U16_F ", nptr=%p, nlen=%" U16_F "\n",
-    chksum, optr, olen, nptr, nlen));
-  x = chksum[0] * 256 + chksum[1];
-  x = ~x & 0xFFFF;
-  while (olen) {
-    oldval = optr[0] * 256 + optr[1];
-    optr += 2;
-    x -= oldval & 0xffff;
-    if (x <= 0) {
-      x--;
-      x &= 0xffff;
-    }
-    olen -= 2;
-  }
-  while (nlen) {
-    newval = nptr[0] * 256 + nptr[1];
-    nptr += 2;
-    x += newval & 0xffff;
-    if (x & 0x10000) {
-      x++;
-      x &= 0xffff;
-    }
-    nlen -= 2;
-  }
-  x = ~x & 0xFFFF;
-  chksum[0] = x / 256;
-  chksum[1] = x & 0xff;
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, ("ip_nat_chksum_adjust: chksum = 0x%x\n", *((u16_t *) chksum)));
-}
-
-#if defined(LWIP_DEBUG) && (LWIP_NAT_DEBUG & LWIP_DBG_ON)
-/**
- * This function dumps an IP address
- *
- * @param addr IP address
- */
-static void
-ip_nat_dbg_dump_ip(const ip_addr_t *addr)
-{
-  LWIP_ASSERT("NULL != addr", NULL != addr);
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, ("%" U16_F ".%" U16_F ".%" U16_F ".%" U16_F,
-    ip4_addr1(addr), ip4_addr2(addr), ip4_addr3(addr), ip4_addr4(addr)));
-}
-
-/**
- * This function dumps an IP header
- *
- * @param msg a message to print
- * @param iphdr IP header
- */
-static void
-ip_nat_dbg_dump(const char *msg, const struct ip_hdr *iphdr)
-{
-  LWIP_ASSERT("NULL != msg", NULL != msg);
-  LWIP_ASSERT("NULL != iphdr", NULL != iphdr);
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, ("%s: IP: (", msg));
-  ip_nat_dbg_dump_ip(&iphdr->src);
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (" --> "));
-  ip_nat_dbg_dump_ip(&iphdr->dest);
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (" id=%" U16_F ", chksum=%" U16_F ")\n",
-    ntohs(IPH_ID(iphdr)), ntohs(IPH_CHKSUM(iphdr))));
-}
-
-/**
- * This function dumps an ICMP echo reply/recho request nat entry.
- *
- * @param msg a message to print
- * @param nat_entry the ICMP NAT entry to print
- */
-static void
-ip_nat_dbg_dump_icmp_nat_entry(const char *msg, const ip_nat_entries_icmp_t *nat_entry)
-{
-  LWIP_ASSERT("NULL != msg", NULL != msg);
-  LWIP_ASSERT("NULL != nat_entry", NULL != nat_entry);
-  LWIP_ASSERT("NULL != nat_entry->common.cfg", NULL != nat_entry->common.cfg);
-  LWIP_ASSERT("NULL != nat_entry->common.cfg->entry.out_if",
-    NULL != nat_entry->common.cfg->entry.out_if);
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, ("%s", msg));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, ("ICMP : ("));
-  ip_nat_dbg_dump_ip(&(nat_entry->common.source));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (" --> "));
-  ip_nat_dbg_dump_ip(&(nat_entry->common.dest));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (" id=%" U16_F, ntohs(nat_entry->id)));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (", seq=%" U16_F, ntohs(nat_entry->seqno)));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (") mapped at ("));
-  ip_nat_dbg_dump_ip(&(nat_entry->common.cfg->entry.out_if->ip_addr));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (" --> "));
-  ip_nat_dbg_dump_ip(&(nat_entry->common.dest));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (" id=%" U16_F, ntohs(nat_entry->id)));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (", seq=%" U16_F, ntohs(nat_entry->seqno)));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (")\n"));
-}
-
-/**
- * This function dumps an TCP nat entry.
- *
- * @param msg a message to print
- * @param nat_entry the TCP NAT entry to print
- */
-static void
-ip_nat_dbg_dump_tcp_nat_entry(const char *msg, const ip_nat_entries_tcp_t *nat_entry)
-{
-  LWIP_ASSERT("NULL != msg", NULL != msg);
-  LWIP_ASSERT("NULL != nat_entry", NULL != nat_entry);
-  LWIP_ASSERT("NULL != nat_entry->common.cfg", NULL != nat_entry->common.cfg);
-  LWIP_ASSERT("NULL != nat_entry->common.cfg->entry.out_if",
-    NULL != nat_entry->common.cfg->entry.out_if);
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, ("%s", msg));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, ("TCP : ("));
-  ip_nat_dbg_dump_ip(&(nat_entry->common.source));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (":%" U16_F, ntohs(nat_entry->sport)));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (" --> "));
-  ip_nat_dbg_dump_ip(&(nat_entry->common.dest));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (":%" U16_F, ntohs(nat_entry->dport)));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (") mapped at ("));
-  ip_nat_dbg_dump_ip(&(nat_entry->common.cfg->entry.out_if->ip_addr));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (":%" U16_F, ntohs(nat_entry->nport)));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (" --> "));
-  ip_nat_dbg_dump_ip(&(nat_entry->common.dest));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (":%" U16_F, ntohs(nat_entry->dport)));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (")\n"));
-}
-
-/**
- * This function dumps a UDP NAT entry.
- *
- * @param msg a message to print
- * @param nat_entry the UDP NAT entry to print
- */
-static void
-ip_nat_dbg_dump_udp_nat_entry(const char *msg, const ip_nat_entries_udp_t *nat_entry)
-{
-  LWIP_ASSERT("NULL != msg", NULL != msg);
-  LWIP_ASSERT("NULL != nat_entry", NULL != nat_entry);
-  LWIP_ASSERT("NULL != nat_entry->common.cfg", NULL != nat_entry->common.cfg);
-  LWIP_ASSERT("NULL != nat_entry->common.cfg->entry.out_if",
-    NULL != nat_entry->common.cfg->entry.out_if);
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, ("%s", msg));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, ("UDP : ("));
-  ip_nat_dbg_dump_ip(&(nat_entry->common.source));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (":%" U16_F, ntohs(nat_entry->sport)));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (" --> "));
-  ip_nat_dbg_dump_ip(&(nat_entry->common.dest));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (":%" U16_F, ntohs(nat_entry->dport)));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (") mapped at ("));
-  ip_nat_dbg_dump_ip(&(nat_entry->common.cfg->entry.out_if->ip_addr));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (":%" U16_F, ntohs(nat_entry->nport)));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (" --> "));
-  ip_nat_dbg_dump_ip(&(nat_entry->common.dest));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (":%" U16_F, ntohs(nat_entry->dport)));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (")\n"));
-}
-
-/** Prints some info when creating a new NAT entry */
-static void
-ip_nat_dbg_dump_init(ip_nat_conf_t *ip_nat_cfg_new)
-{
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, ("ip_nat_init: added new NAT interface\n"));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, ("ip_nat_init:   "));
-  ip_nat_dbg_dump_ip(&(ip_nat_cfg_new->entry.source_net));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, ("/"));
-  ip_nat_dbg_dump_ip(&(ip_nat_cfg_new->entry.source_netmask));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, ("@"));
-  ip_nat_dbg_dump_ip(&(ip_nat_cfg_new->entry.in_if->ip_addr));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (" --> "));
-  ip_nat_dbg_dump_ip(&(ip_nat_cfg_new->entry.dest_net));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, ("/"));
-  ip_nat_dbg_dump_ip(&(ip_nat_cfg_new->entry.dest_netmask));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, ("@"));
-  ip_nat_dbg_dump_ip(&(ip_nat_cfg_new->entry.out_if->ip_addr));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, ("\n"));
-}
-
-/** Prints some info when removing a NAT entry */
-static void
-ip_nat_dbg_dump_remove(ip_nat_conf_t *cur)
-{
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, ("ip_nat_remove: removing existing NAT interface\n"));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, ("ip_nat_remove:   "));
-  ip_nat_dbg_dump_ip(&(cur->entry.source_net));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, ("/"));
-  ip_nat_dbg_dump_ip(&(cur->entry.source_netmask));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, ("@"));
-  ip_nat_dbg_dump_ip(&(cur->entry.in_if->ip_addr));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, (" --> "));
-  ip_nat_dbg_dump_ip(&(cur->entry.dest_net));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, ("/"));
-  ip_nat_dbg_dump_ip(&(cur->entry.dest_netmask));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, ("@"));
-  ip_nat_dbg_dump_ip(&(cur->entry.out_if->ip_addr));
-  LWIP_DEBUGF(LWIP_NAT_DEBUG, ("\n"));
-}
-#endif /* defined(LWIP_DEBUG) && (LWIP_NAT_DEBUG & LWIP_DBG_ON) */
-
-#endif /* IP_NAT */
diff --git a/src/core/timers.c b/src/core/timers.c
index 44d986cc..0dba9272 100644
--- a/src/core/timers.c
+++ b/src/core/timers.c
@@ -53,7 +53,6 @@
 #include "lwip/autoip.h"
 #include "lwip/igmp.h"
 #include "lwip/dns.h"
-#include "lwip/ip_nat.h"
 
 
 /** The one and only timeout list */
@@ -215,22 +214,6 @@ dns_timer(void *arg)
 }
 #endif /* LWIP_DNS */
 
-#if IP_NAT
-/**
- * Timer callback function that calls ip_nat_tmr() and reschedules itself.
- *
- * @param arg unused argument
- */
-static void
-nat_timer(void *arg)
-{
-  LWIP_UNUSED_ARG(arg);
-  LWIP_DEBUGF(TIMERS_DEBUG, ("tcpip: nat_timer()\n"));
-  ip_nat_tmr();
-  sys_timeout(LWIP_NAT_TMR_INTERVAL_SEC, nat_timer, NULL);
-}
-#endif /* IP_NAT */
-
 /** Initialize this module */
 void sys_timeouts_init(void)
 {
@@ -253,9 +236,6 @@ void sys_timeouts_init(void)
 #if LWIP_DNS
   sys_timeout(DNS_TMR_INTERVAL, dns_timer, NULL);
 #endif /* LWIP_DNS */
-#if IP_NAT
-  sys_timeout(LWIP_NAT_TMR_INTERVAL_SEC, nat_timer, NULL);
-#endif /* IP_NAT */
 
 #if NO_SYS
   /* Initialise timestamp for sys_check_timeouts */
diff --git a/src/include/ipv4/lwip/ip_nat.h b/src/include/ipv4/lwip/ip_nat.h
deleted file mode 100644
index 0810785e..00000000
--- a/src/include/ipv4/lwip/ip_nat.h
+++ /dev/null
@@ -1,51 +0,0 @@
-/***************************************************************************
- * Template - A brief description for this module.
- * Copyright (c) 2008 Christian Walter, © Embedded Solutions, Vienna 2006.
- *
- * $Id: ip_nat.h,v 1.1 2010/05/05 19:34:23 goldsimon Exp $
- ***************************************************************************/
-
-#ifndef __LWIP_NAT_H__
-#define __LWIP_NAT_H__
-
-#include "lwip/err.h"
-#include "lwip/ip_addr.h"
-#include "lwip/opt.h"
-
-#if IP_NAT
-
-/** Timer interval at which to call ip_nat_tmr() */
-#define LWIP_NAT_TMR_INTERVAL_SEC        5
-
-#ifdef __cplusplus
-extern "C" {
-#endif /* __cplusplus */
-
-struct netif;
-struct pbuf;
-
-typedef struct ip_nat_entry
-{
-  ip_addr_t    source_net;
-  ip_addr_t    source_netmask;
-  ip_addr_t    dest_net;
-  ip_addr_t    dest_netmask;
-  struct netif *out_if;
-  struct netif *in_if;
-} ip_nat_entry_t;
-
-void  ip_nat_init(void);
-void  ip_nat_tmr(void);
-u8_t  ip_nat_input(struct pbuf *p);
-u8_t  ip_nat_out(struct pbuf *p);
-
-err_t ip_nat_add(const ip_nat_entry_t *new_entry);
-void  ip_nat_remove(const ip_nat_entry_t *remove_entry);
-
-#ifdef __cplusplus
-}
-#endif /* __cplusplus */
-
-#endif /* IP_NAT */
-
-#endif /* __LWIP_NAT_H__ */
diff --git a/src/include/lwip/opt.h b/src/include/lwip/opt.h
index 0433156e..81d98970 100644
--- a/src/include/lwip/opt.h
+++ b/src/include/lwip/opt.h
@@ -466,11 +466,6 @@
 #define IP_FORWARD                      0
 #endif
 
-/** IP_NAT==1: Enables network address translation code */
-#ifndef IP_NAT
-#define IP_NAT                          0
-#endif
-
 /**
  * IP_OPTIONS_ALLOWED: Defines the behavior for IP options.
  *      IP_OPTIONS_ALLOWED==0: All packets with IP options are dropped.