diff --git a/CHANGELOG b/CHANGELOG
index dbab0d7b..a50cfa26 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -56,6 +56,14 @@ HISTORY
 
 
   ++ Bugfixes:
+
+  2010-01-29: Simon Goldschmidt
+  * ip_addr.h, inet.h, def.h, inet.c, def.c, more: Cleanly separate the
+    portability file inet.h and its contents from the stack: moved htonX-
+    functions to def.h (and the new def.c - they are not ipv4 dependent),
+    let inet.h depend on ip_addr.h and not the other way round.
+    This fixes bug #28732.
+
   2010-01-28: Kieran Mansley
   * tcp.c: Ensure ssthresh >= 2*MSS
 
diff --git a/src/api/netdb.c b/src/api/netdb.c
index 88135a55..06290190 100644
--- a/src/api/netdb.c
+++ b/src/api/netdb.c
@@ -296,7 +296,7 @@ lwip_getaddrinfo(const char *nodename, const char *servname,
     }
   } else {
     /* service location specified, use loopback address */
-    addr.addr = htonl(INADDR_LOOPBACK);
+    addr.addr = htonl(IPADDR_LOOPBACK);
   }
 
   total_size = sizeof(struct addrinfo) + sizeof(struct sockaddr_in);
diff --git a/src/core/def.c b/src/core/def.c
new file mode 100644
index 00000000..003daedf
--- /dev/null
+++ b/src/core/def.c
@@ -0,0 +1,108 @@
+/**
+ * @file
+ * Common functions used throughout the stack.
+ *
+ */
+
+/*
+ * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
+ * 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.
+ *
+ * Author: Simon Goldschmidt
+ *
+ */
+
+#include "lwip/opt.h"
+#include "lwip/def.h"
+
+/**
+ * These are reference implementations of the byte swapping functions.
+ * Again with the aim of being simple, correct and fully portable.
+ * Byte swapping is the second thing you would want to optimize. You will
+ * need to port it to your architecture and in your cc.h:
+ * 
+ * #define LWIP_PLATFORM_BYTESWAP 1
+ * #define LWIP_PLATFORM_HTONS(x) <your_htons>
+ * #define LWIP_PLATFORM_HTONL(x) <your_htonl>
+ *
+ * Note ntohs() and ntohl() are merely references to the htonx counterparts.
+ */
+
+#if (LWIP_PLATFORM_BYTESWAP == 0) && (BYTE_ORDER == LITTLE_ENDIAN)
+
+/**
+ * Convert an u16_t from host- to network byte order.
+ *
+ * @param n u16_t in host byte order
+ * @return n in network byte order
+ */
+u16_t
+htons(u16_t n)
+{
+  return ((n & 0xff) << 8) | ((n & 0xff00) >> 8);
+}
+
+/**
+ * Convert an u16_t from network- to host byte order.
+ *
+ * @param n u16_t in network byte order
+ * @return n in host byte order
+ */
+u16_t
+ntohs(u16_t n)
+{
+  return htons(n);
+}
+
+/**
+ * Convert an u32_t from host- to network byte order.
+ *
+ * @param n u32_t in host byte order
+ * @return n in network byte order
+ */
+u32_t
+htonl(u32_t n)
+{
+  return ((n & 0xff) << 24) |
+    ((n & 0xff00) << 8) |
+    ((n & 0xff0000UL) >> 8) |
+    ((n & 0xff000000UL) >> 24);
+}
+
+/**
+ * Convert an u32_t from network- to host byte order.
+ *
+ * @param n u32_t in network byte order
+ * @return n in host byte order
+ */
+u32_t
+ntohl(u32_t n)
+{
+  return htonl(n);
+}
+
+#endif /* (LWIP_PLATFORM_BYTESWAP == 0) && (BYTE_ORDER == LITTLE_ENDIAN) */
diff --git a/src/core/dhcp.c b/src/core/dhcp.c
index 9318655b..ebfcaa69 100644
--- a/src/core/dhcp.c
+++ b/src/core/dhcp.c
@@ -77,7 +77,7 @@
 #include "lwip/udp.h"
 #include "lwip/ip_addr.h"
 #include "lwip/netif.h"
-#include "lwip/inet.h"
+#include "lwip/def.h"
 #include "lwip/sys.h"
 #include "lwip/dhcp.h"
 #include "lwip/autoip.h"
diff --git a/src/core/dns.c b/src/core/dns.c
index ac22e953..871a8233 100644
--- a/src/core/dns.c
+++ b/src/core/dns.c
@@ -84,7 +84,7 @@
 
 /** DNS server IP address */
 #ifndef DNS_SERVER_ADDRESS
-#define DNS_SERVER_ADDRESS        inet_addr("208.67.222.222") /* resolver1.opendns.com */
+#define DNS_SERVER_ADDRESS        ipaddr_addr("208.67.222.222") /* resolver1.opendns.com */
 #endif
 
 /** DNS server port address */
@@ -361,7 +361,7 @@ dns_init_local()
  *
  * @param hostname Hostname to look for in the local host-list
  * @return The first IP address for the hostname in the local host-list or
- *         INADDR_NONE if not found.
+ *         IPADDR_NONE if not found.
  */
 static u32_t
 dns_lookup_local(const char *hostname)
@@ -382,7 +382,7 @@ dns_lookup_local(const char *hostname)
     }
   }
 #endif /* DNS_LOCAL_HOSTLIST_IS_DYNAMIC */
-  return INADDR_NONE;
+  return IPADDR_NONE;
 }
 
 #if DNS_LOCAL_HOSTLIST_IS_DYNAMIC
@@ -461,7 +461,7 @@ dns_local_addhost(const char *hostname, const struct ip_addr *addr)
  *
  * @param name the hostname to look up
  * @return the hostname's IP address, as u32_t (instead of struct ip_addr to
- *         better check for failure: != INADDR_NONE) or INADDR_NONE if the hostname
+ *         better check for failure: != IPADDR_NONE) or IPADDR_NONE if the hostname
  *         was not found in the cached dns_table.
  */
 static u32_t
@@ -472,12 +472,12 @@ dns_lookup(const char *name)
   u32_t addr;
 #endif /* DNS_LOCAL_HOSTLIST || defined(DNS_LOOKUP_LOCAL_EXTERN) */
 #if DNS_LOCAL_HOSTLIST
-  if ((addr = dns_lookup_local(name)) != INADDR_NONE) {
+  if ((addr = dns_lookup_local(name)) != IPADDR_NONE) {
     return addr;
   }
 #endif /* DNS_LOCAL_HOSTLIST */
 #ifdef DNS_LOOKUP_LOCAL_EXTERN
-  if((addr = DNS_LOOKUP_LOCAL_EXTERN(name)) != INADDR_NONE) {
+  if((addr = DNS_LOOKUP_LOCAL_EXTERN(name)) != IPADDR_NONE) {
     return addr;
   }
 #endif /* DNS_LOOKUP_LOCAL_EXTERN */
@@ -493,7 +493,7 @@ dns_lookup(const char *name)
     }
   }
 
-  return INADDR_NONE;
+  return IPADDR_NONE;
 }
 
 #if DNS_DOES_NAME_CHECK
@@ -971,15 +971,15 @@ dns_gethostbyname(const char *hostname, struct ip_addr *addr, dns_found_callback
 
 #if LWIP_HAVE_LOOPIF
   if (strcmp(hostname,"localhost")==0) {
-    addr->addr = htonl(INADDR_LOOPBACK);
+    addr->addr = htonl(IPADDR_LOOPBACK);
     return ERR_OK;
   }
 #endif /* LWIP_HAVE_LOOPIF */
 
   /* host name already in octet notation? set ip addr and return ERR_OK
    * already have this address cached? */
-  if (((addr->addr = inet_addr(hostname)) != INADDR_NONE) ||
-      ((addr->addr = dns_lookup(hostname)) != INADDR_NONE)) {
+  if (((addr->addr = ipaddr_addr(hostname)) != IPADDR_NONE) ||
+      ((addr->addr = dns_lookup(hostname)) != IPADDR_NONE)) {
     return ERR_OK;
   }
 
diff --git a/src/core/ipv4/icmp.c b/src/core/ipv4/icmp.c
index 27d54028..2ff78ffb 100644
--- a/src/core/ipv4/icmp.c
+++ b/src/core/ipv4/icmp.c
@@ -44,7 +44,6 @@
 #if LWIP_ICMP /* don't build if not configured for use in lwipopts.h */
 
 #include "lwip/icmp.h"
-#include "lwip/inet.h"
 #include "lwip/inet_chksum.h"
 #include "lwip/ip.h"
 #include "lwip/def.h"
diff --git a/src/core/ipv4/igmp.c b/src/core/ipv4/igmp.c
index 3358a633..9254190f 100644
--- a/src/core/ipv4/igmp.c
+++ b/src/core/ipv4/igmp.c
@@ -86,7 +86,6 @@ Steve Reynolds
 #include "lwip/def.h"
 #include "lwip/mem.h"
 #include "lwip/ip.h"
-#include "lwip/inet.h"
 #include "lwip/inet_chksum.h"
 #include "lwip/netif.h"
 #include "lwip/icmp.h"
diff --git a/src/core/ipv4/inet.c b/src/core/ipv4/inet.c
index 69baf1d5..e283a576 100644
--- a/src/core/ipv4/inet.c
+++ b/src/core/ipv4/inet.c
@@ -40,239 +40,3 @@
 
 #include "lwip/inet.h"
 
-/* Here for now until needed in other places in lwIP */
-#ifndef isprint
-#define in_range(c, lo, up)  ((u8_t)c >= lo && (u8_t)c <= up)
-#define isprint(c)           in_range(c, 0x20, 0x7f)
-#define isdigit(c)           in_range(c, '0', '9')
-#define isxdigit(c)          (isdigit(c) || in_range(c, 'a', 'f') || in_range(c, 'A', 'F'))
-#define islower(c)           in_range(c, 'a', 'z')
-#define isspace(c)           (c == ' ' || c == '\f' || c == '\n' || c == '\r' || c == '\t' || c == '\v')
-#endif    
-    
-/**
- * Ascii internet address interpretation routine.
- * The value returned is in network order.
- *
- * @param cp IP address in ascii represenation (e.g. "127.0.0.1")
- * @return ip address in network order
- */
-u32_t
-inet_addr(const char *cp)
-{
-  struct in_addr val;
-
-  if (inet_aton(cp, &val)) {
-    return (val.s_addr);
-  }
-  return (INADDR_NONE);
-}
-
-/**
- * Check whether "cp" is a valid ascii representation
- * of an Internet address and convert to a binary address.
- * Returns 1 if the address is valid, 0 if not.
- * This replaces inet_addr, the return value from which
- * cannot distinguish between failure and a local broadcast address.
- *
- * @param cp IP address in ascii represenation (e.g. "127.0.0.1")
- * @param addr pointer to which to save the ip address in network order
- * @return 1 if cp could be converted to addr, 0 on failure
- */
-int
-inet_aton(const char *cp, struct in_addr *addr)
-{
-  u32_t val;
-  u8_t base;
-  char c;
-  u32_t parts[4];
-  u32_t *pp = parts;
-
-  c = *cp;
-  for (;;) {
-    /*
-     * Collect number up to ``.''.
-     * Values are specified as for C:
-     * 0x=hex, 0=octal, 1-9=decimal.
-     */
-    if (!isdigit(c))
-      return (0);
-    val = 0;
-    base = 10;
-    if (c == '0') {
-      c = *++cp;
-      if (c == 'x' || c == 'X') {
-        base = 16;
-        c = *++cp;
-      } else
-        base = 8;
-    }
-    for (;;) {
-      if (isdigit(c)) {
-        val = (val * base) + (int)(c - '0');
-        c = *++cp;
-      } else if (base == 16 && isxdigit(c)) {
-        val = (val << 4) | (int)(c + 10 - (islower(c) ? 'a' : 'A'));
-        c = *++cp;
-      } else
-        break;
-    }
-    if (c == '.') {
-      /*
-       * Internet format:
-       *  a.b.c.d
-       *  a.b.c   (with c treated as 16 bits)
-       *  a.b (with b treated as 24 bits)
-       */
-      if (pp >= parts + 3)
-        return (0);
-      *pp++ = val;
-      c = *++cp;
-    } else
-      break;
-  }
-  /*
-   * Check for trailing characters.
-   */
-  if (c != '\0' && !isspace(c))
-    return (0);
-  /*
-   * Concoct the address according to
-   * the number of parts specified.
-   */
-  switch (pp - parts + 1) {
-
-  case 0:
-    return (0);       /* initial nondigit */
-
-  case 1:             /* a -- 32 bits */
-    break;
-
-  case 2:             /* a.b -- 8.24 bits */
-    if (val > 0xffffffUL)
-      return (0);
-    val |= parts[0] << 24;
-    break;
-
-  case 3:             /* a.b.c -- 8.8.16 bits */
-    if (val > 0xffff)
-      return (0);
-    val |= (parts[0] << 24) | (parts[1] << 16);
-    break;
-
-  case 4:             /* a.b.c.d -- 8.8.8.8 bits */
-    if (val > 0xff)
-      return (0);
-    val |= (parts[0] << 24) | (parts[1] << 16) | (parts[2] << 8);
-    break;
-  }
-  if (addr)
-    addr->s_addr = htonl(val);
-  return (1);
-}
-
-/**
- * Convert numeric IP address into decimal dotted ASCII representation.
- * returns ptr to static buffer; not reentrant!
- *
- * @param addr ip address in network order to convert
- * @return pointer to a global static (!) buffer that holds the ASCII
- *         represenation of addr
- */
-char *
-inet_ntoa(struct in_addr addr)
-{
-  static char str[16];
-  u32_t s_addr = addr.s_addr;
-  char inv[3];
-  char *rp;
-  u8_t *ap;
-  u8_t rem;
-  u8_t n;
-  u8_t i;
-
-  rp = str;
-  ap = (u8_t *)&s_addr;
-  for(n = 0; n < 4; n++) {
-    i = 0;
-    do {
-      rem = *ap % (u8_t)10;
-      *ap /= (u8_t)10;
-      inv[i++] = '0' + rem;
-    } while(*ap);
-    while(i--)
-      *rp++ = inv[i];
-    *rp++ = '.';
-    ap++;
-  }
-  *--rp = 0;
-  return str;
-}
-
-/**
- * These are reference implementations of the byte swapping functions.
- * Again with the aim of being simple, correct and fully portable.
- * Byte swapping is the second thing you would want to optimize. You will
- * need to port it to your architecture and in your cc.h:
- * 
- * #define LWIP_PLATFORM_BYTESWAP 1
- * #define LWIP_PLATFORM_HTONS(x) <your_htons>
- * #define LWIP_PLATFORM_HTONL(x) <your_htonl>
- *
- * Note ntohs() and ntohl() are merely references to the htonx counterparts.
- */
-
-#if (LWIP_PLATFORM_BYTESWAP == 0) && (BYTE_ORDER == LITTLE_ENDIAN)
-
-/**
- * Convert an u16_t from host- to network byte order.
- *
- * @param n u16_t in host byte order
- * @return n in network byte order
- */
-u16_t
-htons(u16_t n)
-{
-  return ((n & 0xff) << 8) | ((n & 0xff00) >> 8);
-}
-
-/**
- * Convert an u16_t from network- to host byte order.
- *
- * @param n u16_t in network byte order
- * @return n in host byte order
- */
-u16_t
-ntohs(u16_t n)
-{
-  return htons(n);
-}
-
-/**
- * Convert an u32_t from host- to network byte order.
- *
- * @param n u32_t in host byte order
- * @return n in network byte order
- */
-u32_t
-htonl(u32_t n)
-{
-  return ((n & 0xff) << 24) |
-    ((n & 0xff00) << 8) |
-    ((n & 0xff0000UL) >> 8) |
-    ((n & 0xff000000UL) >> 24);
-}
-
-/**
- * Convert an u32_t from network- to host byte order.
- *
- * @param n u32_t in network byte order
- * @return n in host byte order
- */
-u32_t
-ntohl(u32_t n)
-{
-  return htonl(n);
-}
-
-#endif /* (LWIP_PLATFORM_BYTESWAP == 0) && (BYTE_ORDER == LITTLE_ENDIAN) */
diff --git a/src/core/ipv4/inet_chksum.c b/src/core/ipv4/inet_chksum.c
index d7401229..aa248d28 100644
--- a/src/core/ipv4/inet_chksum.c
+++ b/src/core/ipv4/inet_chksum.c
@@ -39,7 +39,7 @@
 #include "lwip/opt.h"
 
 #include "lwip/inet_chksum.h"
-#include "lwip/inet.h"
+#include "lwip/def.h"
 
 #include <stddef.h>
 
diff --git a/src/core/ipv4/ip.c b/src/core/ipv4/ip.c
index d6950fd6..eb5537cb 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/inet.h"
 #include "lwip/inet_chksum.h"
 #include "lwip/netif.h"
 #include "lwip/icmp.h"
diff --git a/src/core/ipv4/ip_addr.c b/src/core/ipv4/ip_addr.c
index 94bf4678..e668abca 100644
--- a/src/core/ipv4/ip_addr.c
+++ b/src/core/ipv4/ip_addr.c
@@ -38,7 +38,6 @@
 
 #include "lwip/opt.h"
 #include "lwip/ip_addr.h"
-#include "lwip/inet.h"
 #include "lwip/netif.h"
 
 #define IP_ADDR_ANY_VALUE 0x00000000UL
@@ -82,3 +81,172 @@ u8_t ip_addr_isbroadcast(struct ip_addr *addr, struct netif *netif)
   else
     return 0;
 }
+
+/* Here for now until needed in other places in lwIP */
+#ifndef isprint
+#define in_range(c, lo, up)  ((u8_t)c >= lo && (u8_t)c <= up)
+#define isprint(c)           in_range(c, 0x20, 0x7f)
+#define isdigit(c)           in_range(c, '0', '9')
+#define isxdigit(c)          (isdigit(c) || in_range(c, 'a', 'f') || in_range(c, 'A', 'F'))
+#define islower(c)           in_range(c, 'a', 'z')
+#define isspace(c)           (c == ' ' || c == '\f' || c == '\n' || c == '\r' || c == '\t' || c == '\v')
+#endif    
+    
+/**
+ * Ascii internet address interpretation routine.
+ * The value returned is in network order.
+ *
+ * @param cp IP address in ascii represenation (e.g. "127.0.0.1")
+ * @return ip address in network order
+ */
+u32_t
+ipaddr_addr(const char *cp)
+{
+  struct ip_addr val;
+
+  if (ipaddr_aton(cp, &val)) {
+    return (val.addr);
+  }
+  return (IPADDR_NONE);
+}
+
+/**
+ * Check whether "cp" is a valid ascii representation
+ * of an Internet address and convert to a binary address.
+ * Returns 1 if the address is valid, 0 if not.
+ * This replaces inet_addr, the return value from which
+ * cannot distinguish between failure and a local broadcast address.
+ *
+ * @param cp IP address in ascii represenation (e.g. "127.0.0.1")
+ * @param addr pointer to which to save the ip address in network order
+ * @return 1 if cp could be converted to addr, 0 on failure
+ */
+int
+ipaddr_aton(const char *cp, struct ip_addr *addr)
+{
+  u32_t val;
+  u8_t base;
+  char c;
+  u32_t parts[4];
+  u32_t *pp = parts;
+
+  c = *cp;
+  for (;;) {
+    /*
+     * Collect number up to ``.''.
+     * Values are specified as for C:
+     * 0x=hex, 0=octal, 1-9=decimal.
+     */
+    if (!isdigit(c))
+      return (0);
+    val = 0;
+    base = 10;
+    if (c == '0') {
+      c = *++cp;
+      if (c == 'x' || c == 'X') {
+        base = 16;
+        c = *++cp;
+      } else
+        base = 8;
+    }
+    for (;;) {
+      if (isdigit(c)) {
+        val = (val * base) + (int)(c - '0');
+        c = *++cp;
+      } else if (base == 16 && isxdigit(c)) {
+        val = (val << 4) | (int)(c + 10 - (islower(c) ? 'a' : 'A'));
+        c = *++cp;
+      } else
+        break;
+    }
+    if (c == '.') {
+      /*
+       * Internet format:
+       *  a.b.c.d
+       *  a.b.c   (with c treated as 16 bits)
+       *  a.b (with b treated as 24 bits)
+       */
+      if (pp >= parts + 3)
+        return (0);
+      *pp++ = val;
+      c = *++cp;
+    } else
+      break;
+  }
+  /*
+   * Check for trailing characters.
+   */
+  if (c != '\0' && !isspace(c))
+    return (0);
+  /*
+   * Concoct the address according to
+   * the number of parts specified.
+   */
+  switch (pp - parts + 1) {
+
+  case 0:
+    return (0);       /* initial nondigit */
+
+  case 1:             /* a -- 32 bits */
+    break;
+
+  case 2:             /* a.b -- 8.24 bits */
+    if (val > 0xffffffUL)
+      return (0);
+    val |= parts[0] << 24;
+    break;
+
+  case 3:             /* a.b.c -- 8.8.16 bits */
+    if (val > 0xffff)
+      return (0);
+    val |= (parts[0] << 24) | (parts[1] << 16);
+    break;
+
+  case 4:             /* a.b.c.d -- 8.8.8.8 bits */
+    if (val > 0xff)
+      return (0);
+    val |= (parts[0] << 24) | (parts[1] << 16) | (parts[2] << 8);
+    break;
+  }
+  if (addr)
+    addr->addr = htonl(val);
+  return (1);
+}
+
+/**
+ * Convert numeric IP address into decimal dotted ASCII representation.
+ * returns ptr to static buffer; not reentrant!
+ *
+ * @param addr ip address in network order to convert
+ * @return pointer to a global static (!) buffer that holds the ASCII
+ *         represenation of addr
+ */
+char *
+ipaddr_ntoa(struct ip_addr *addr)
+{
+  static char str[16];
+  u32_t s_addr = addr->addr;
+  char inv[3];
+  char *rp;
+  u8_t *ap;
+  u8_t rem;
+  u8_t n;
+  u8_t i;
+
+  rp = str;
+  ap = (u8_t *)&s_addr;
+  for(n = 0; n < 4; n++) {
+    i = 0;
+    do {
+      rem = *ap % (u8_t)10;
+      *ap /= (u8_t)10;
+      inv[i++] = '0' + rem;
+    } while(*ap);
+    while(i--)
+      *rp++ = inv[i];
+    *rp++ = '.';
+    ap++;
+  }
+  *--rp = 0;
+  return str;
+}
\ No newline at end of file
diff --git a/src/core/ipv4/ip_frag.c b/src/core/ipv4/ip_frag.c
index 852d0b9b..d8c62a89 100644
--- a/src/core/ipv4/ip_frag.c
+++ b/src/core/ipv4/ip_frag.c
@@ -40,8 +40,7 @@
 
 #include "lwip/opt.h"
 #include "lwip/ip_frag.h"
-#include "lwip/ip.h"
-#include "lwip/inet.h"
+#include "lwip/def.h"
 #include "lwip/inet_chksum.h"
 #include "lwip/netif.h"
 #include "lwip/snmp.h"
diff --git a/src/core/raw.c b/src/core/raw.c
index 96980a03..f012c65e 100644
--- a/src/core/raw.c
+++ b/src/core/raw.c
@@ -44,7 +44,6 @@
 
 #include "lwip/def.h"
 #include "lwip/memp.h"
-#include "lwip/inet.h"
 #include "lwip/ip_addr.h"
 #include "lwip/netif.h"
 #include "lwip/raw.h"
diff --git a/src/core/tcp_in.c b/src/core/tcp_in.c
index 48d857e2..f5b0641c 100644
--- a/src/core/tcp_in.c
+++ b/src/core/tcp_in.c
@@ -51,7 +51,6 @@
 #include "lwip/netif.h"
 #include "lwip/mem.h"
 #include "lwip/memp.h"
-#include "lwip/inet.h"
 #include "lwip/inet_chksum.h"
 #include "lwip/stats.h"
 #include "lwip/snmp.h"
diff --git a/src/core/tcp_out.c b/src/core/tcp_out.c
index db9a7af6..820b3572 100644
--- a/src/core/tcp_out.c
+++ b/src/core/tcp_out.c
@@ -49,7 +49,6 @@
 #include "lwip/sys.h"
 #include "lwip/ip_addr.h"
 #include "lwip/netif.h"
-#include "lwip/inet.h"
 #include "lwip/inet_chksum.h"
 #include "lwip/stats.h"
 #include "lwip/snmp.h"
diff --git a/src/core/udp.c b/src/core/udp.c
index a28c2d07..6cbc71ec 100644
--- a/src/core/udp.c
+++ b/src/core/udp.c
@@ -53,7 +53,6 @@
 #include "lwip/udp.h"
 #include "lwip/def.h"
 #include "lwip/memp.h"
-#include "lwip/inet.h"
 #include "lwip/inet_chksum.h"
 #include "lwip/ip_addr.h"
 #include "lwip/netif.h"
diff --git a/src/include/ipv4/lwip/inet.h b/src/include/ipv4/lwip/inet.h
index 6f30d0d1..c1f5cbd0 100644
--- a/src/include/ipv4/lwip/inet.h
+++ b/src/include/ipv4/lwip/inet.h
@@ -33,68 +33,66 @@
 #define __LWIP_INET_H__
 
 #include "lwip/opt.h"
+#include "lwip/def.h"
+#include "lwip/ip_addr.h"
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-/* For compatibility with BSD code */
+/** For compatibility with BSD code */
 struct in_addr {
   u32_t s_addr;
 };
 
-#define INADDR_NONE         ((u32_t)0xffffffffUL)  /* 255.255.255.255 */
-#define INADDR_LOOPBACK     ((u32_t)0x7f000001UL)  /* 127.0.0.1 */
-#define INADDR_ANY          ((u32_t)0x00000000UL)  /* 0.0.0.0 */
-#define INADDR_BROADCAST    ((u32_t)0xffffffffUL)  /* 255.255.255.255 */
+/** 255.255.255.255 */
+#define INADDR_NONE         IPADDR_NONE
+/** 127.0.0.1 */
+#define INADDR_LOOPBACK     IPADDR_LOOPBACK
+/** 0.0.0.0 */
+#define INADDR_ANY          IPADDR_ANY
+/** 255.255.255.255 */
+#define INADDR_BROADCAST    IPADDR_BROADCAST
 
-u32_t inet_addr(const char *cp);
-int inet_aton(const char *cp, struct in_addr *addr);
-char *inet_ntoa(struct in_addr addr); /* returns ptr to static buffer; not reentrant! */
+/* Definitions of the bits in an Internet address integer.
 
-#ifdef htons
-#undef htons
-#endif /* htons */
-#ifdef htonl
-#undef htonl
-#endif /* htonl */
-#ifdef ntohs
-#undef ntohs
-#endif /* ntohs */
-#ifdef ntohl
-#undef ntohl
-#endif /* ntohl */
+   On subnets, host and network parts are found according to
+   the subnet mask, not these masks.  */
+#define IN_CLASSA(a)        IP_CLASSA(a)
+#define IN_CLASSA_NET       IP_CLASSA_NET
+#define IN_CLASSA_NSHIFT    IP_CLASSA_NSHIFT
+#define IN_CLASSA_HOST      IP_CLASSA_HOST
+#define IN_CLASSA_MAX       IP_CLASSA_MAX
 
-#ifndef LWIP_PLATFORM_BYTESWAP
-#define LWIP_PLATFORM_BYTESWAP 0
-#endif
+#define IN_CLASSB(b)        IP_CLASSB(b)
+#define IN_CLASSB_NET       IP_CLASSB_NET
+#define IN_CLASSB_NSHIFT    IP_CLASSB_NSHIFT
+#define IN_CLASSB_HOST      IP_CLASSB_HOST
+#define IN_CLASSB_MAX       IP_CLASSB_MAX
 
-#if BYTE_ORDER == BIG_ENDIAN
-#define htons(x) (x)
-#define ntohs(x) (x)
-#define htonl(x) (x)
-#define ntohl(x) (x)
-#else /* BYTE_ORDER != BIG_ENDIAN */
-#ifdef LWIP_PREFIX_BYTEORDER_FUNCS
-/* workaround for naming collisions on some platforms */
-#define htons lwip_htons
-#define ntohs lwip_ntohs
-#define htonl lwip_htonl
-#define ntohl lwip_ntohl
-#endif /* LWIP_PREFIX_BYTEORDER_FUNCS */
-#if LWIP_PLATFORM_BYTESWAP
-#define htons(x) LWIP_PLATFORM_HTONS(x)
-#define ntohs(x) LWIP_PLATFORM_HTONS(x)
-#define htonl(x) LWIP_PLATFORM_HTONL(x)
-#define ntohl(x) LWIP_PLATFORM_HTONL(x)
-#else /* LWIP_PLATFORM_BYTESWAP */
-u16_t htons(u16_t x);
-u16_t ntohs(u16_t x);
-u32_t htonl(u32_t x);
-u32_t ntohl(u32_t x);
-#endif /* LWIP_PLATFORM_BYTESWAP */
+#define IN_CLASSC(c)        IP_CLASSC(c)
+#define IN_CLASSC_NET       IP_CLASSC_NET
+#define IN_CLASSC_NSHIFT    IP_CLASSC_NSHIFT
+#define IN_CLASSC_HOST      IP_CLASSC_HOST
+#define IN_CLASSC_MAX       IP_CLASSC_MAX
 
-#endif /* BYTE_ORDER == BIG_ENDIAN */
+#define IN_CLASSD(d)        IP_CLASSD(d)
+#define IN_CLASSD_NET       IP_CLASSD_NET     /* These ones aren't really */
+#define IN_CLASSD_NSHIFT    IP_CLASSD_NSHIFT  /*   net and host fields, but */
+#define IN_CLASSD_HOST      IP_CLASSD_HOST    /*   routing needn't know. */
+#define IN_CLASSD_MAX       IP_CLASSD_MAX
+
+#define IN_MULTICAST(a)     IP_MULTICAST(a)
+
+#define IN_EXPERIMENTAL(a)  IP_EXPERIMENTAL(a)
+#define IN_BADCLASS(a)      IP_BADCLASS(a)
+
+#define IN_LOOPBACKNET      IP_LOOPBACKNET
+
+/* directly map this to the lwip internal functions */
+#define inet_addr(cp)         ipaddr_addr(cp)
+#define inet_aton(cp, addr)   ipaddr_aton(cp, (struct ip_addr*)addr)
+#define inet_ntoa(addr)       ipaddr_ntoa((struct ip_addr*)&(addr))
 
 #ifdef __cplusplus
 }
diff --git a/src/include/ipv4/lwip/ip_addr.h b/src/include/ipv4/lwip/ip_addr.h
index 298e6576..eb0eb00b 100644
--- a/src/include/ipv4/lwip/ip_addr.h
+++ b/src/include/ipv4/lwip/ip_addr.h
@@ -33,8 +33,7 @@
 #define __LWIP_IP_ADDR_H__
 
 #include "lwip/opt.h"
-
-#include "lwip/inet.h"
+#include "lwip/def.h"
 
 #ifdef __cplusplus
 extern "C" {
@@ -79,38 +78,47 @@ extern const struct ip_addr ip_addr_broadcast;
 #define IP_ADDR_ANY         ((struct ip_addr *)&ip_addr_any)
 #define IP_ADDR_BROADCAST   ((struct ip_addr *)&ip_addr_broadcast)
 
+/** 255.255.255.255 */
+#define IPADDR_NONE         ((u32_t)0xffffffffUL)
+/** 127.0.0.1 */
+#define IPADDR_LOOPBACK     ((u32_t)0x7f000001UL)
+/** 0.0.0.0 */
+#define IPADDR_ANY          ((u32_t)0x00000000UL)
+/** 255.255.255.255 */
+#define IPADDR_BROADCAST    ((u32_t)0xffffffffUL)
+
 /* Definitions of the bits in an Internet address integer.
 
    On subnets, host and network parts are found according to
    the subnet mask, not these masks.  */
+#define IP_CLASSA(a)        ((((u32_t)(a)) & 0x80000000UL) == 0)
+#define IP_CLASSA_NET       0xff000000
+#define IP_CLASSA_NSHIFT    24
+#define IP_CLASSA_HOST      (0xffffffff & ~IP_CLASSA_NET)
+#define IP_CLASSA_MAX       128
 
-#define IN_CLASSA(a)        ((((u32_t)(a)) & 0x80000000UL) == 0)
-#define IN_CLASSA_NET       0xff000000
-#define IN_CLASSA_NSHIFT    24
-#define IN_CLASSA_HOST      (0xffffffff & ~IN_CLASSA_NET)
-#define IN_CLASSA_MAX       128
+#define IP_CLASSB(a)        ((((u32_t)(a)) & 0xc0000000UL) == 0x80000000UL)
+#define IP_CLASSB_NET       0xffff0000
+#define IP_CLASSB_NSHIFT    16
+#define IP_CLASSB_HOST      (0xffffffff & ~IP_CLASSB_NET)
+#define IP_CLASSB_MAX       65536
 
-#define IN_CLASSB(a)        ((((u32_t)(a)) & 0xc0000000UL) == 0x80000000UL)
-#define IN_CLASSB_NET       0xffff0000
-#define IN_CLASSB_NSHIFT    16
-#define IN_CLASSB_HOST      (0xffffffff & ~IN_CLASSB_NET)
-#define IN_CLASSB_MAX       65536
+#define IP_CLASSC(a)        ((((u32_t)(a)) & 0xe0000000UL) == 0xc0000000UL)
+#define IP_CLASSC_NET       0xffffff00
+#define IP_CLASSC_NSHIFT    8
+#define IP_CLASSC_HOST      (0xffffffff & ~IP_CLASSC_NET)
 
-#define IN_CLASSC(a)        ((((u32_t)(a)) & 0xe0000000UL) == 0xc0000000UL)
-#define IN_CLASSC_NET       0xffffff00
-#define IN_CLASSC_NSHIFT    8
-#define IN_CLASSC_HOST      (0xffffffff & ~IN_CLASSC_NET)
+#define IP_CLASSD(a)        (((u32_t)(a) & 0xf0000000UL) == 0xe0000000UL)
+#define IP_CLASSD_NET       0xf0000000          /* These ones aren't really */
+#define IP_CLASSD_NSHIFT    28                  /*   net and host fields, but */
+#define IP_CLASSD_HOST      0x0fffffff          /*   routing needn't know. */
+#define IP_MULTICAST(a)     IP_CLASSD(a)
 
-#define IN_CLASSD(a)        (((u32_t)(a) & 0xf0000000UL) == 0xe0000000UL)
-#define IN_CLASSD_NET       0xf0000000          /* These ones aren't really */
-#define IN_CLASSD_NSHIFT    28                  /*   net and host fields, but */
-#define IN_CLASSD_HOST      0x0fffffff          /*   routing needn't know. */
-#define IN_MULTICAST(a)     IN_CLASSD(a)
+#define IP_EXPERIMENTAL(a)  (((u32_t)(a) & 0xf0000000UL) == 0xf0000000UL)
+#define IP_BADCLASS(a)      (((u32_t)(a) & 0xf0000000UL) == 0xf0000000UL)
 
-#define IN_EXPERIMENTAL(a)  (((u32_t)(a) & 0xf0000000UL) == 0xf0000000UL)
-#define IN_BADCLASS(a)      (((u32_t)(a) & 0xf0000000UL) == 0xf0000000UL)
+#define IP_LOOPBACKNET      127                 /* official! */
 
-#define IN_LOOPBACKNET      127                 /* official! */
 
 #define IP4_ADDR(ipaddr, a,b,c,d) \
         (ipaddr)->addr = htonl(((u32_t)((a) & 0xff) << 24) | \
@@ -161,10 +169,13 @@ u8_t ip_addr_isbroadcast(struct ip_addr *, struct netif *);
 #define ip4_addr3(ipaddr) ((u16_t)(ntohl((ipaddr)->addr) >> 8) & 0xff)
 #define ip4_addr4(ipaddr) ((u16_t)(ntohl((ipaddr)->addr)) & 0xff)
 
-/**
- * Same as inet_ntoa() but takes a struct ip_addr*
- */
-#define ip_ntoa(addr)  ((addr != NULL) ? inet_ntoa(*((struct in_addr*)(addr))) : "NULL")
+/** For backwards compatibility */
+#define ip_ntoa(addr)  ipaddr_ntoa(addr)
+
+u32_t ipaddr_addr(const char *cp);
+int ipaddr_aton(const char *cp, struct ip_addr *addr);
+/** returns ptr to static buffer; not reentrant! */
+char *ipaddr_ntoa(struct ip_addr *addr);
 
 #ifdef __cplusplus
 }
diff --git a/src/include/lwip/def.h b/src/include/lwip/def.h
index d2ed251d..b500af2c 100644
--- a/src/include/lwip/def.h
+++ b/src/include/lwip/def.h
@@ -32,8 +32,13 @@
 #ifndef __LWIP_DEF_H__
 #define __LWIP_DEF_H__
 
-/* this might define NULL already */
+/* arch.h might define NULL already */
 #include "lwip/arch.h"
+#include "lwip/opt.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
 
 #define LWIP_MAX(x , y)  (((x) > (y)) ? (x) : (y))
 #define LWIP_MIN(x , y)  (((x) < (y)) ? (x) : (y))
@@ -42,6 +47,53 @@
 #define NULL ((void *)0)
 #endif
 
+#ifdef htons
+#undef htons
+#endif /* htons */
+#ifdef htonl
+#undef htonl
+#endif /* htonl */
+#ifdef ntohs
+#undef ntohs
+#endif /* ntohs */
+#ifdef ntohl
+#undef ntohl
+#endif /* ntohl */
+
+#ifndef LWIP_PLATFORM_BYTESWAP
+#define LWIP_PLATFORM_BYTESWAP 0
+#endif
+
+#if BYTE_ORDER == BIG_ENDIAN
+#define htons(x) (x)
+#define ntohs(x) (x)
+#define htonl(x) (x)
+#define ntohl(x) (x)
+#else /* BYTE_ORDER != BIG_ENDIAN */
+#ifdef LWIP_PREFIX_BYTEORDER_FUNCS
+/* workaround for naming collisions on some platforms */
+#define htons lwip_htons
+#define ntohs lwip_ntohs
+#define htonl lwip_htonl
+#define ntohl lwip_ntohl
+#endif /* LWIP_PREFIX_BYTEORDER_FUNCS */
+#if LWIP_PLATFORM_BYTESWAP
+#define htons(x) LWIP_PLATFORM_HTONS(x)
+#define ntohs(x) LWIP_PLATFORM_HTONS(x)
+#define htonl(x) LWIP_PLATFORM_HTONL(x)
+#define ntohl(x) LWIP_PLATFORM_HTONL(x)
+#else /* LWIP_PLATFORM_BYTESWAP */
+u16_t htons(u16_t x);
+u16_t ntohs(u16_t x);
+u32_t htonl(u32_t x);
+u32_t ntohl(u32_t x);
+#endif /* LWIP_PLATFORM_BYTESWAP */
+
+#endif /* BYTE_ORDER == BIG_ENDIAN */
+
+#ifdef __cplusplus
+}
+#endif
 
 #endif /* __LWIP_DEF_H__ */
 
diff --git a/src/include/lwip/netif.h b/src/include/lwip/netif.h
index c5c3cd4e..59c97543 100644
--- a/src/include/lwip/netif.h
+++ b/src/include/lwip/netif.h
@@ -40,7 +40,7 @@
 
 #include "lwip/ip_addr.h"
 
-#include "lwip/inet.h"
+#include "lwip/def.h"
 #include "lwip/pbuf.h"
 #if LWIP_DHCP
 struct dhcp;
diff --git a/src/include/lwip/raw.h b/src/include/lwip/raw.h
index 395f7dbd..8ddcf3e9 100644
--- a/src/include/lwip/raw.h
+++ b/src/include/lwip/raw.h
@@ -37,7 +37,7 @@
 #if LWIP_RAW /* don't build if not configured for use in lwipopts.h */
 
 #include "lwip/pbuf.h"
-#include "lwip/inet.h"
+#include "lwip/def.h"
 #include "lwip/ip.h"
 #include "lwip/ip_addr.h"
 
diff --git a/src/netif/etharp.c b/src/netif/etharp.c
index 28c7f7e7..1e79a693 100644
--- a/src/netif/etharp.c
+++ b/src/netif/etharp.c
@@ -47,7 +47,8 @@
 
 #if LWIP_ARP || LWIP_ETHERNET
 
-#include "lwip/inet.h"
+#include "lwip/ip_addr.h"
+#include "lwip/def.h"
 #include "lwip/ip.h"
 #include "lwip/stats.h"
 #include "lwip/snmp.h"
diff --git a/src/netif/ppp/auth.c b/src/netif/ppp/auth.c
index c86c982e..0b2f9dde 100644
--- a/src/netif/ppp/auth.c
+++ b/src/netif/ppp/auth.c
@@ -82,6 +82,8 @@
 #include "cbcp.h"
 #endif /* CBCP_SUPPORT */
 
+#include "lwip/inet.h"
+
 #include <string.h>
 
 #if 0 /* UNUSED */
diff --git a/src/netif/ppp/ipcp.c b/src/netif/ppp/ipcp.c
index cf25f476..d49fe90d 100644
--- a/src/netif/ppp/ipcp.c
+++ b/src/netif/ppp/ipcp.c
@@ -63,6 +63,8 @@
 #include "vj.h"
 #include "ipcp.h"
 
+#include "lwip/inet.h"
+
 #include <string.h>
 
 /* #define OLD_CI_ADDRS 1 */ /* Support deprecated address negotiation. */
@@ -166,8 +168,6 @@ static void ipcp_clear_addrs (int);
                      (x) == CONFNAK ? "NAK" : "REJ")
 
 
-#define inet_ntoa(addr) ip_ntoa(((struct ip_addr*)&(addr)))
-
 /*
  * ipcp_init - Initialize IPCP.
  */
diff --git a/src/netif/ppp/ppp.c b/src/netif/ppp/ppp.c
index cec00164..a48de956 100644
--- a/src/netif/ppp/ppp.c
+++ b/src/netif/ppp/ppp.c
@@ -1249,12 +1249,12 @@ GetMask(u32_t addr)
   u32_t mask, nmask;
 
   htonl(addr);
-  if (IN_CLASSA(addr)) { /* determine network mask for address class */
-    nmask = IN_CLASSA_NET;
-  } else if (IN_CLASSB(addr)) {
-    nmask = IN_CLASSB_NET;
+  if (IP_CLASSA(addr)) { /* determine network mask for address class */
+    nmask = IP_CLASSA_NET;
+  } else if (IP_CLASSB(addr)) {
+    nmask = IP_CLASSB_NET;
   } else { 
-    nmask = IN_CLASSC_NET;
+    nmask = IP_CLASSC_NET;
   }
 
   /* class D nets are disallowed by bad_ip_adrs */