diff --git a/src/core/inet_chksum.c b/src/core/inet_chksum.c
index 01a8fa96..9f68e472 100644
--- a/src/core/inet_chksum.c
+++ b/src/core/inet_chksum.c
@@ -309,7 +309,7 @@ inet_cksum_pseudo_base(struct pbuf *p, u8_t proto, u16_t proto_len, u32_t acc)
  */
 u16_t
 inet_chksum_pseudo(struct pbuf *p, u8_t proto, u16_t proto_len,
-       ip_addr_t *src, ip_addr_t *dest)
+       const ip_addr_t *src, const ip_addr_t *dest)
 {
   u32_t acc;
   u32_t addr;
@@ -421,7 +421,7 @@ inet_cksum_pseudo_partial_base(struct pbuf *p, u8_t proto, u16_t proto_len,
  */
 u16_t
 inet_chksum_pseudo_partial(struct pbuf *p, u8_t proto, u16_t proto_len,
-       u16_t chksum_len, ip_addr_t *src, ip_addr_t *dest)
+       u16_t chksum_len, const ip_addr_t *src, const ip_addr_t *dest)
 {
   u32_t acc;
   u32_t addr;
diff --git a/src/core/ipv4/ip4.c b/src/core/ipv4/ip4.c
index a2551d65..3693e2f9 100644
--- a/src/core/ipv4/ip4.c
+++ b/src/core/ipv4/ip4.c
@@ -108,7 +108,7 @@ static u16_t ip_id;
  * @return the netif on which to send to reach dest
  */
 struct netif *
-ip_route(ip_addr_t *dest)
+ip_route(const ip_addr_t *dest)
 {
   struct netif *netif;
 
@@ -649,7 +649,7 @@ ip_input(struct pbuf *p, struct netif *inp)
  *  unique identifiers independent of destination"
  */
 err_t
-ip_output_if(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
+ip_output_if(struct pbuf *p, const ip_addr_t *src, const ip_addr_t *dest,
              u8_t ttl, u8_t tos,
              u8_t proto, struct netif *netif)
 {
@@ -663,12 +663,12 @@ ip_output_if(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
  * @ param ip_options pointer to the IP options, copied into the IP header
  * @ param optlen length of ip_options
  */
-err_t ip_output_if_opt(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
+err_t ip_output_if_opt(struct pbuf *p, const ip_addr_t *src, const ip_addr_t *dest,
        u8_t ttl, u8_t tos, u8_t proto, struct netif *netif, void *ip_options,
        u16_t optlen)
 {
 #endif /* IP_OPTIONS_SEND */
-  ip_addr_t *src_used = src;
+  const ip_addr_t *src_used = src;
   if (dest != IP_HDRINCL) {
     if (ip_addr_isany(src)) {
       src_used = &netif->ip_addr;
@@ -688,7 +688,7 @@ err_t ip_output_if_opt(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
  * when it is 'any'.
  */
 err_t
-ip_output_if_src(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
+ip_output_if_src(struct pbuf *p, const ip_addr_t *src, const ip_addr_t *dest,
              u8_t ttl, u8_t tos,
              u8_t proto, struct netif *netif)
 {
@@ -700,7 +700,7 @@ ip_output_if_src(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
  * Same as ip_output_if_opt() but 'src' address is not replaced by netif address
  * when it is 'any'.
  */
-err_t ip_output_if_opt_src(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
+err_t ip_output_if_opt_src(struct pbuf *p, const ip_addr_t *src, const ip_addr_t *dest,
        u8_t ttl, u8_t tos, u8_t proto, struct netif *netif, void *ip_options,
        u16_t optlen)
 {
@@ -861,7 +861,7 @@ err_t ip_output_if_opt_src(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
  *         see ip_output_if() for more return values
  */
 err_t
-ip_output(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
+ip_output(struct pbuf *p, const ip_addr_t *src, const ip_addr_t *dest,
           u8_t ttl, u8_t tos, u8_t proto)
 {
   struct netif *netif;
@@ -898,7 +898,7 @@ ip_output(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
  *         see ip_output_if() for more return values
  */
 err_t
-ip_output_hinted(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
+ip_output_hinted(struct pbuf *p, const ip_addr_t *src, const ip_addr_t *dest,
           u8_t ttl, u8_t tos, u8_t proto, u8_t *addr_hint)
 {
   struct netif *netif;
diff --git a/src/core/ipv4/ip_frag.c b/src/core/ipv4/ip_frag.c
index 34509270..f54d7db6 100644
--- a/src/core/ipv4/ip_frag.c
+++ b/src/core/ipv4/ip_frag.c
@@ -677,7 +677,7 @@ ipfrag_free_pbuf_custom(struct pbuf *p)
  * @return ERR_OK if sent successfully, err_t otherwise
  */
 err_t 
-ip_frag(struct pbuf *p, struct netif *netif, ip_addr_t *dest)
+ip_frag(struct pbuf *p, struct netif *netif, const ip_addr_t *dest)
 {
   struct pbuf *rambuf;
 #if IP_FRAG_USES_STATIC_BUF
diff --git a/src/core/netif.c b/src/core/netif.c
index 36e801b3..82442f3d 100644
--- a/src/core/netif.c
+++ b/src/core/netif.c
@@ -95,7 +95,7 @@ static err_t netif_null_output_ip6(struct netif *netif, struct pbuf *p, ip6_addr
 #endif
 
 #if LWIP_HAVE_LOOPIF
-static err_t netif_loop_output_ipv4(struct netif *netif, struct pbuf *p, ip_addr_t* addr);
+static err_t netif_loop_output_ipv4(struct netif *netif, struct pbuf *p, const ip_addr_t* addr);
 #if LWIP_IPV6
 static err_t netif_loop_output_ipv6(struct netif *netif, struct pbuf *p, ip6_addr_t* addr);
 #endif
@@ -171,8 +171,8 @@ netif_init(void)
  * @return netif, or NULL if failed.
  */
 struct netif *
-netif_add(struct netif *netif, ip_addr_t *ipaddr, ip_addr_t *netmask,
-  ip_addr_t *gw, void *state, netif_init_fn init, netif_input_fn input)
+netif_add(struct netif *netif, const ip_addr_t *ipaddr, const ip_addr_t *netmask,
+  const ip_addr_t *gw, void *state, netif_init_fn init, netif_input_fn input)
 {
 #if LWIP_IPV6
   u32_t i;
@@ -277,8 +277,8 @@ netif_add(struct netif *netif, ip_addr_t *ipaddr, ip_addr_t *netmask,
  * @param gw the new default gateway
  */
 void
-netif_set_addr(struct netif *netif, ip_addr_t *ipaddr, ip_addr_t *netmask,
-    ip_addr_t *gw)
+netif_set_addr(struct netif *netif, const ip_addr_t *ipaddr, const ip_addr_t *netmask,
+    const ip_addr_t *gw)
 {
   netif_set_ipaddr(netif, ipaddr);
   netif_set_netmask(netif, netmask);
@@ -383,7 +383,7 @@ netif_find(char *name)
  * default gateway
  */
 void
-netif_set_ipaddr(struct netif *netif, ip_addr_t *ipaddr)
+netif_set_ipaddr(struct netif *netif, const ip_addr_t *ipaddr)
 {
   /* TODO: Handling of obsolete pcbs */
   /* See:  http://mail.gnu.org/archive/html/lwip-users/2003-03/msg00118.html */
@@ -448,7 +448,7 @@ netif_set_ipaddr(struct netif *netif, ip_addr_t *ipaddr)
  * @note call netif_set_addr() if you also want to change ip address and netmask
  */
 void
-netif_set_gw(struct netif *netif, ip_addr_t *gw)
+netif_set_gw(struct netif *netif, const ip_addr_t *gw)
 {
   ip_addr_set(&(netif->gw), gw);
   LWIP_DEBUGF(NETIF_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("netif: GW address of interface %c%c set to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
@@ -469,7 +469,7 @@ netif_set_gw(struct netif *netif, ip_addr_t *gw)
  * default gateway
  */
 void
-netif_set_netmask(struct netif *netif, ip_addr_t *netmask)
+netif_set_netmask(struct netif *netif, const ip_addr_t *netmask)
 {
   snmp_delete_iprteidx_tree(0, netif);
   /* set new netmask to netif */
@@ -763,7 +763,7 @@ netif_loop_output(struct netif *netif, struct pbuf *p)
 }
 
 static err_t
-netif_loop_output_ipv4(struct netif *netif, struct pbuf *p, ip_addr_t* addr)
+netif_loop_output_ipv4(struct netif *netif, struct pbuf *p, const ip_addr_t* addr)
 {
   LWIP_UNUSED_ARG(addr);
   return netif_loop_output(netif, p);
diff --git a/src/core/raw.c b/src/core/raw.c
index a0bf0e55..efa25844 100644
--- a/src/core/raw.c
+++ b/src/core/raw.c
@@ -170,7 +170,7 @@ raw_input(struct pbuf *p, struct netif *inp)
  * @see raw_disconnect()
  */
 err_t
-raw_bind(struct raw_pcb *pcb, ip_addr_t *ipaddr)
+raw_bind(struct raw_pcb *pcb, const ip_addr_t *ipaddr)
 {
   ipX_addr_set_ipaddr(PCB_ISIPV6(pcb), &pcb->local_ip, ipaddr);
   return ERR_OK;
@@ -190,7 +190,7 @@ raw_bind(struct raw_pcb *pcb, ip_addr_t *ipaddr)
  * @see raw_disconnect() and raw_sendto()
  */
 err_t
-raw_connect(struct raw_pcb *pcb, ip_addr_t *ipaddr)
+raw_connect(struct raw_pcb *pcb, const ip_addr_t *ipaddr)
 {
   ipX_addr_set_ipaddr(PCB_ISIPV6(pcb), &pcb->remote_ip, ipaddr);
   return ERR_OK;
@@ -231,14 +231,14 @@ raw_recv(struct raw_pcb *pcb, raw_recv_fn recv, void *recv_arg)
  *
  */
 err_t
-raw_sendto(struct raw_pcb *pcb, struct pbuf *p, ip_addr_t *ipaddr)
+raw_sendto(struct raw_pcb *pcb, struct pbuf *p, const ip_addr_t *ipaddr)
 {
   err_t err;
   struct netif *netif;
   ipX_addr_t *src_ip;
   struct pbuf *q; /* q will be sent down the stack */
   s16_t header_size;
-  ipX_addr_t *dst_ip = ip_2_ipX(ipaddr);
+  const ipX_addr_t *dst_ip = ip_2_ipX(ipaddr);
 
   LWIP_DEBUGF(RAW_DEBUG | LWIP_DBG_TRACE, ("raw_sendto\n"));
 
diff --git a/src/core/tcp.c b/src/core/tcp.c
index d73a614b..2bcf2dc4 100644
--- a/src/core/tcp.c
+++ b/src/core/tcp.c
@@ -436,7 +436,7 @@ tcp_abort(struct tcp_pcb *pcb)
  *         ERR_OK if bound
  */
 err_t
-tcp_bind(struct tcp_pcb *pcb, ip_addr_t *ipaddr, u16_t port)
+tcp_bind(struct tcp_pcb *pcb, const ip_addr_t *ipaddr, u16_t port)
 {
   int i;
   int max_pcb_list = NUM_TCP_PCB_LISTS;
@@ -726,7 +726,7 @@ again:
  *         other err_t values if connect request couldn't be sent
  */
 err_t
-tcp_connect(struct tcp_pcb *pcb, ip_addr_t *ipaddr, u16_t port,
+tcp_connect(struct tcp_pcb *pcb, const ip_addr_t *ipaddr, u16_t port,
       tcp_connected_fn connected)
 {
   err_t ret;
diff --git a/src/core/udp.c b/src/core/udp.c
index 47c6cfe5..1f58a891 100644
--- a/src/core/udp.c
+++ b/src/core/udp.c
@@ -540,7 +540,7 @@ udp_send_chksum(struct udp_pcb *pcb, struct pbuf *p,
  */
 err_t
 udp_sendto(struct udp_pcb *pcb, struct pbuf *p,
-  ip_addr_t *dst_ip, u16_t dst_port)
+  const ip_addr_t *dst_ip, u16_t dst_port)
 {
 #if LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_UDP
   return udp_sendto_chksum(pcb, p, dst_ip, dst_port, 0, 0);
@@ -548,12 +548,12 @@ udp_sendto(struct udp_pcb *pcb, struct pbuf *p,
 
 /** Same as udp_sendto(), but with checksum */
 err_t
-udp_sendto_chksum(struct udp_pcb *pcb, struct pbuf *p, ip_addr_t *dst_ip,
+udp_sendto_chksum(struct udp_pcb *pcb, struct pbuf *p, const ip_addr_t *dst_ip,
                   u16_t dst_port, u8_t have_chksum, u16_t chksum)
 {
 #endif /* LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_UDP */
   struct netif *netif;
-  ipX_addr_t *dst_ip_route = ip_2_ipX(dst_ip);
+  const ipX_addr_t *dst_ip_route = ip_2_ipX(dst_ip);
 
   LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, ("udp_send\n"));
 
@@ -612,7 +612,7 @@ udp_sendto_chksum(struct udp_pcb *pcb, struct pbuf *p, ip_addr_t *dst_ip,
  */
 err_t
 udp_sendto_if(struct udp_pcb *pcb, struct pbuf *p,
-  ip_addr_t *dst_ip, u16_t dst_port, struct netif *netif)
+  const ip_addr_t *dst_ip, u16_t dst_port, struct netif *netif)
 {
 #if LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_UDP
   return udp_sendto_if_chksum(pcb, p, dst_ip, dst_port, netif, 0, 0);
@@ -620,12 +620,12 @@ udp_sendto_if(struct udp_pcb *pcb, struct pbuf *p,
 
 /** Same as udp_sendto_if(), but with checksum */
 err_t
-udp_sendto_if_chksum(struct udp_pcb *pcb, struct pbuf *p, ip_addr_t *dst_ip,
+udp_sendto_if_chksum(struct udp_pcb *pcb, struct pbuf *p, const ip_addr_t *dst_ip,
                      u16_t dst_port, struct netif *netif, u8_t have_chksum,
                      u16_t chksum)
 {
 #endif /* LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_UDP */
-  ip_addr_t *src_ip;
+  const ip_addr_t *src_ip;
 
   /* PCB local address is IP_ANY_ADDR? */
 #if LWIP_IPV6
@@ -670,7 +670,7 @@ udp_sendto_if_chksum(struct udp_pcb *pcb, struct pbuf *p, ip_addr_t *dst_ip,
 /** Same as udp_sendto_if(), but with source address */
 err_t
 udp_sendto_if_src(struct udp_pcb *pcb, struct pbuf *p,
-  ip_addr_t *dst_ip, u16_t dst_port, struct netif *netif, ip_addr_t *src_ip)
+  const ip_addr_t *dst_ip, u16_t dst_port, struct netif *netif, const ip_addr_t *src_ip)
 {
 #if LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_UDP
   return udp_sendto_if_src_chksum(pcb, p, dst_ip, dst_port, netif, 0, 0, src_ip);
@@ -678,9 +678,9 @@ udp_sendto_if_src(struct udp_pcb *pcb, struct pbuf *p,
 
 /** Same as udp_sendto_if_src(), but with checksum */
 err_t
-udp_sendto_if_src_chksum(struct udp_pcb *pcb, struct pbuf *p, ip_addr_t *dst_ip,
+udp_sendto_if_src_chksum(struct udp_pcb *pcb, struct pbuf *p, const ip_addr_t *dst_ip,
                      u16_t dst_port, struct netif *netif, u8_t have_chksum,
-                     u16_t chksum, ip_addr_t *src_ip)
+                     u16_t chksum, const ip_addr_t *src_ip)
 {
 #endif /* LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_UDP */
   struct udp_hdr *udphdr;
@@ -883,7 +883,7 @@ udp_sendto_if_src_chksum(struct udp_pcb *pcb, struct pbuf *p, ip_addr_t *dst_ip,
  * @see udp_disconnect()
  */
 err_t
-udp_bind(struct udp_pcb *pcb, ip_addr_t *ipaddr, u16_t port)
+udp_bind(struct udp_pcb *pcb, const ip_addr_t *ipaddr, u16_t port)
 {
   struct udp_pcb *ipcb;
   u8_t rebind;
@@ -969,7 +969,7 @@ udp_bind(struct udp_pcb *pcb, ip_addr_t *ipaddr, u16_t port)
  * @see udp_disconnect()
  */
 err_t
-udp_connect(struct udp_pcb *pcb, ip_addr_t *ipaddr, u16_t port)
+udp_connect(struct udp_pcb *pcb, const ip_addr_t *ipaddr, u16_t port)
 {
   struct udp_pcb *ipcb;
 
diff --git a/src/include/lwip/inet.h b/src/include/lwip/inet.h
index 2895d61e..890a2578 100644
--- a/src/include/lwip/inet.h
+++ b/src/include/lwip/inet.h
@@ -111,8 +111,9 @@ struct in_addr {
 /* directly map this to the lwip internal functions */
 #define inet_addr(cp)         ipaddr_addr(cp)
 #define inet_aton(cp, addr)   ipaddr_aton(cp, (ip_addr_t*)addr)
-#define inet_ntoa(addr)       ipaddr_ntoa((ip_addr_t*)&(addr))
-#define inet_ntoa_r(addr, buf, buflen) ipaddr_ntoa_r((ip_addr_t*)&(addr), buf, buflen)
+/* if those casts were originally introduced solely to strip off any const qualifier, they could be removed. */
+#define inet_ntoa(addr)       ipaddr_ntoa((const ip_addr_t*)&(addr))
+#define inet_ntoa_r(addr, buf, buflen) ipaddr_ntoa_r((const ip_addr_t*)&(addr), buf, buflen)
 
 #ifdef __cplusplus
 }
diff --git a/src/include/lwip/inet_chksum.h b/src/include/lwip/inet_chksum.h
index 4171d0ae..e40f2169 100644
--- a/src/include/lwip/inet_chksum.h
+++ b/src/include/lwip/inet_chksum.h
@@ -73,9 +73,9 @@ extern "C" {
 u16_t inet_chksum(void *dataptr, u16_t len);
 u16_t inet_chksum_pbuf(struct pbuf *p);
 u16_t inet_chksum_pseudo(struct pbuf *p, u8_t proto, u16_t proto_len,
-       ip_addr_t *src, ip_addr_t *dest);
+       const ip_addr_t *src, const ip_addr_t *dest);
 u16_t inet_chksum_pseudo_partial(struct pbuf *p, u8_t proto,
-       u16_t proto_len, u16_t chksum_len, ip_addr_t *src, ip_addr_t *dest);
+       u16_t proto_len, u16_t chksum_len, const ip_addr_t *src, const ip_addr_t *dest);
 #if LWIP_CHKSUM_COPY_ALGORITHM
 u16_t lwip_chksum_copy(void *dst, const void *src, u16_t len);
 #endif /* LWIP_CHKSUM_COPY_ALGORITHM */
diff --git a/src/include/lwip/ip4.h b/src/include/lwip/ip4.h
index c49a771e..1c1eea29 100644
--- a/src/include/lwip/ip4.h
+++ b/src/include/lwip/ip4.h
@@ -112,23 +112,23 @@ PACK_STRUCT_END
 
 
 #define ip_init() /* Compatibility define, no init needed. */
-struct netif *ip_route(ip_addr_t *dest);
+struct netif *ip_route(const ip_addr_t *dest);
 err_t ip_input(struct pbuf *p, struct netif *inp);
-err_t ip_output(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
+err_t ip_output(struct pbuf *p, const ip_addr_t *src, const ip_addr_t *dest,
        u8_t ttl, u8_t tos, u8_t proto);
-err_t ip_output_if(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
+err_t ip_output_if(struct pbuf *p, const ip_addr_t *src, const ip_addr_t *dest,
        u8_t ttl, u8_t tos, u8_t proto, struct netif *netif);
-err_t ip_output_if_src(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
+err_t ip_output_if_src(struct pbuf *p, const ip_addr_t *src, const ip_addr_t *dest,
        u8_t ttl, u8_t tos, u8_t proto, struct netif *netif);
 #if LWIP_NETIF_HWADDRHINT
-err_t ip_output_hinted(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
+err_t ip_output_hinted(struct pbuf *p, const ip_addr_t *src, const ip_addr_t *dest,
        u8_t ttl, u8_t tos, u8_t proto, u8_t *addr_hint);
 #endif /* LWIP_NETIF_HWADDRHINT */
 #if IP_OPTIONS_SEND
-err_t ip_output_if_opt(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
+err_t ip_output_if_opt(struct pbuf *p, const ip_addr_t *src, const ip_addr_t *dest,
        u8_t ttl, u8_t tos, u8_t proto, struct netif *netif, void *ip_options,
        u16_t optlen);
-err_t ip_output_if_opt_src(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
+err_t ip_output_if_opt_src(struct pbuf *p, const ip_addr_t *src, const ip_addr_t *dest,
        u8_t ttl, u8_t tos, u8_t proto, struct netif *netif, void *ip_options,
        u16_t optlen);
 #endif /* IP_OPTIONS_SEND */
diff --git a/src/include/lwip/ip4_addr.h b/src/include/lwip/ip4_addr.h
index 6f6318bd..e46314c2 100644
--- a/src/include/lwip/ip4_addr.h
+++ b/src/include/lwip/ip4_addr.h
@@ -89,8 +89,8 @@ extern const ip_addr_t ip_addr_broadcast;
 /** IP_ADDR_ can be used as a fixed IP address
  *  for the wildcard and the broadcast address
  */
-#define IP_ADDR_ANY         ((ip_addr_t *)&ip_addr_any)
-#define IP_ADDR_BROADCAST   ((ip_addr_t *)&ip_addr_broadcast)
+#define IP_ADDR_ANY         (&ip_addr_any)
+#define IP_ADDR_BROADCAST   (&ip_addr_broadcast)
 
 /** 255.255.255.255 */
 #define IPADDR_NONE         ((u32_t)0xffffffffUL)
diff --git a/src/include/lwip/ip_frag.h b/src/include/lwip/ip_frag.h
index 4d395c72..5e7227ee 100644
--- a/src/include/lwip/ip_frag.h
+++ b/src/include/lwip/ip_frag.h
@@ -81,7 +81,7 @@ struct pbuf_custom_ref {
 #endif /* LWIP_PBUF_CUSTOM_REF_DEFINED */
 #endif /* !IP_FRAG_USES_STATIC_BUF && !LWIP_NETIF_TX_SINGLE_PBUF */
 
-err_t ip_frag(struct pbuf *p, struct netif *netif, ip_addr_t *dest);
+err_t ip_frag(struct pbuf *p, struct netif *netif, const ip_addr_t *dest);
 #endif /* IP_FRAG */
 
 #ifdef __cplusplus
diff --git a/src/include/lwip/netif.h b/src/include/lwip/netif.h
index 9583b6a9..03a820e1 100644
--- a/src/include/lwip/netif.h
+++ b/src/include/lwip/netif.h
@@ -123,7 +123,7 @@ typedef err_t (*netif_input_fn)(struct pbuf *p, struct netif *inp);
  * @param ipaddr The IP address to which the packet shall be sent
  */
 typedef err_t (*netif_output_fn)(struct netif *netif, struct pbuf *p,
-       ip_addr_t *ipaddr);
+       const ip_addr_t *ipaddr);
 #if LWIP_IPV6
 /** Function prototype for netif->output_ip6 functions. Called by lwIP when a packet
  * shall be sent. For ethernet netif, set this to 'ethip6_output' and set
@@ -147,7 +147,7 @@ typedef err_t (*netif_linkoutput_fn)(struct netif *netif, struct pbuf *p);
 typedef void (*netif_status_callback_fn)(struct netif *netif);
 /** Function prototype for netif igmp_mac_filter functions */
 typedef err_t (*netif_igmp_mac_filter_fn)(struct netif *netif,
-       ip_addr_t *group, u8_t action);
+       const ip_addr_t *group, u8_t action);
 #if LWIP_IPV6 && LWIP_IPV6_MLD
 /** Function prototype for netif mld_mac_filter functions */
 typedef err_t (*netif_mld_mac_filter_fn)(struct netif *netif,
@@ -310,12 +310,12 @@ extern struct netif *netif_default;
 
 void netif_init(void);
 
-struct netif *netif_add(struct netif *netif, ip_addr_t *ipaddr, ip_addr_t *netmask,
-      ip_addr_t *gw, void *state, netif_init_fn init, netif_input_fn input);
+struct netif *netif_add(struct netif *netif, const ip_addr_t *ipaddr, const ip_addr_t *netmask,
+      const ip_addr_t *gw, void *state, netif_init_fn init, netif_input_fn input);
 
 void
-netif_set_addr(struct netif *netif, ip_addr_t *ipaddr, ip_addr_t *netmask,
-      ip_addr_t *gw);
+netif_set_addr(struct netif *netif, const ip_addr_t *ipaddr, const ip_addr_t *netmask,
+      const ip_addr_t *gw);
 void netif_remove(struct netif * netif);
 
 /* Returns a network interface given its name. The name is of the form
@@ -326,9 +326,9 @@ struct netif *netif_find(char *name);
 
 void netif_set_default(struct netif *netif);
 
-void netif_set_ipaddr(struct netif *netif, ip_addr_t *ipaddr);
-void netif_set_netmask(struct netif *netif, ip_addr_t *netmask);
-void netif_set_gw(struct netif *netif, ip_addr_t *gw);
+void netif_set_ipaddr(struct netif *netif, const ip_addr_t *ipaddr);
+void netif_set_netmask(struct netif *netif, const ip_addr_t *netmask);
+void netif_set_gw(struct netif *netif, const ip_addr_t *gw);
 
 void netif_set_up(struct netif *netif);
 void netif_set_down(struct netif *netif);
diff --git a/src/include/lwip/raw.h b/src/include/lwip/raw.h
index 5dfb6af4..aae1aebb 100644
--- a/src/include/lwip/raw.h
+++ b/src/include/lwip/raw.h
@@ -59,7 +59,7 @@ struct raw_pcb;
  * if it's not used any more.
  */
 typedef u8_t (*raw_recv_fn)(void *arg, struct raw_pcb *pcb, struct pbuf *p,
-    ip_addr_t *addr);
+    const ip_addr_t *addr);
 
 #if LWIP_IPV6
 /** Function prototype for raw pcb IPv6 receive callback functions.
@@ -108,11 +108,11 @@ struct raw_pcb {
    RAW code. */
 struct raw_pcb * raw_new        (u8_t proto);
 void             raw_remove     (struct raw_pcb *pcb);
-err_t            raw_bind       (struct raw_pcb *pcb, ip_addr_t *ipaddr);
-err_t            raw_connect    (struct raw_pcb *pcb, ip_addr_t *ipaddr);
+err_t            raw_bind       (struct raw_pcb *pcb, const ip_addr_t *ipaddr);
+err_t            raw_connect    (struct raw_pcb *pcb, const ip_addr_t *ipaddr);
 
 void             raw_recv       (struct raw_pcb *pcb, raw_recv_fn recv, void *recv_arg);
-err_t            raw_sendto     (struct raw_pcb *pcb, struct pbuf *p, ip_addr_t *ipaddr);
+err_t            raw_sendto     (struct raw_pcb *pcb, struct pbuf *p, const ip_addr_t *ipaddr);
 err_t            raw_send       (struct raw_pcb *pcb, struct pbuf *p);
 
 #if LWIP_IPV6
diff --git a/src/include/lwip/tcp.h b/src/include/lwip/tcp.h
index 9840a2f7..0f38baf4 100644
--- a/src/include/lwip/tcp.h
+++ b/src/include/lwip/tcp.h
@@ -364,9 +364,9 @@ void             tcp_err     (struct tcp_pcb *pcb, tcp_err_fn err);
 #endif /* TCP_LISTEN_BACKLOG */
 
 void             tcp_recved  (struct tcp_pcb *pcb, u16_t len);
-err_t            tcp_bind    (struct tcp_pcb *pcb, ip_addr_t *ipaddr,
+err_t            tcp_bind    (struct tcp_pcb *pcb, const ip_addr_t *ipaddr,
                               u16_t port);
-err_t            tcp_connect (struct tcp_pcb *pcb, ip_addr_t *ipaddr,
+err_t            tcp_connect (struct tcp_pcb *pcb, const ip_addr_t *ipaddr,
                               u16_t port, tcp_connected_fn connected);
 
 struct tcp_pcb * tcp_listen_with_backlog(struct tcp_pcb *pcb, u8_t backlog);
diff --git a/src/include/lwip/udp.h b/src/include/lwip/udp.h
index be353543..be9579e8 100644
--- a/src/include/lwip/udp.h
+++ b/src/include/lwip/udp.h
@@ -86,7 +86,7 @@ struct udp_pcb;
  * @param port the remote port from which the packet was received
  */
 typedef void (*udp_recv_fn)(void *arg, struct udp_pcb *pcb, struct pbuf *p,
-    ip_addr_t *addr, u16_t port);
+    const ip_addr_t *addr, u16_t port);
 
 #if LWIP_IPV6
 /** Function prototype for udp pcb IPv6 receive callback functions
@@ -123,7 +123,7 @@ struct udp_pcb {
 
 #if LWIP_IGMP
   /** outgoing network interface for multicast packets */
-  ip_addr_t multicast_ip;
+  const ip_addr_t multicast_ip;
 #endif /* LWIP_IGMP */
 
 #if LWIP_UDPLITE
@@ -146,36 +146,36 @@ extern struct udp_pcb *udp_pcbs;
    UDP code. */
 struct udp_pcb * udp_new        (void);
 void             udp_remove     (struct udp_pcb *pcb);
-err_t            udp_bind       (struct udp_pcb *pcb, ip_addr_t *ipaddr,
+err_t            udp_bind       (struct udp_pcb *pcb, const ip_addr_t *ipaddr,
                                  u16_t port);
-err_t            udp_connect    (struct udp_pcb *pcb, ip_addr_t *ipaddr,
+err_t            udp_connect    (struct udp_pcb *pcb, const ip_addr_t *ipaddr,
                                  u16_t port);
 void             udp_disconnect (struct udp_pcb *pcb);
 void             udp_recv       (struct udp_pcb *pcb, udp_recv_fn recv,
                                  void *recv_arg);
 err_t            udp_sendto_if  (struct udp_pcb *pcb, struct pbuf *p,
-                                 ip_addr_t *dst_ip, u16_t dst_port,
+                                 const ip_addr_t *dst_ip, u16_t dst_port,
                                  struct netif *netif);
 err_t            udp_sendto_if_src(struct udp_pcb *pcb, struct pbuf *p,
-                                 ip_addr_t *dst_ip, u16_t dst_port,
-                                 struct netif *netif, ip_addr_t *src_ip);
+                                 const ip_addr_t *dst_ip, u16_t dst_port,
+                                 struct netif *netif, const ip_addr_t *src_ip);
 err_t            udp_sendto     (struct udp_pcb *pcb, struct pbuf *p,
-                                 ip_addr_t *dst_ip, u16_t dst_port);
+                                 const ip_addr_t *dst_ip, u16_t dst_port);
 err_t            udp_send       (struct udp_pcb *pcb, struct pbuf *p);
 
 #if LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_UDP
 err_t            udp_sendto_if_chksum(struct udp_pcb *pcb, struct pbuf *p,
-                                 ip_addr_t *dst_ip, u16_t dst_port,
+                                 const ip_addr_t *dst_ip, u16_t dst_port,
                                  struct netif *netif, u8_t have_chksum,
                                  u16_t chksum);
 err_t            udp_sendto_chksum(struct udp_pcb *pcb, struct pbuf *p,
-                                 ip_addr_t *dst_ip, u16_t dst_port,
+                                 const ip_addr_t *dst_ip, u16_t dst_port,
                                  u8_t have_chksum, u16_t chksum);
 err_t            udp_send_chksum(struct udp_pcb *pcb, struct pbuf *p,
                                  u8_t have_chksum, u16_t chksum);
 err_t            udp_sendto_if_src_chksum(struct udp_pcb *pcb, struct pbuf *p,
-                                 ip_addr_t *dst_ip, u16_t dst_port, struct netif *netif,
-                                 u8_t have_chksum, u16_t chksum, ip_addr_t *src_ip);
+                                 const ip_addr_t *dst_ip, u16_t dst_port, struct netif *netif,
+                                 u8_t have_chksum, u16_t chksum, const ip_addr_t *src_ip);
 #endif /* LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_UDP */
 
 #define          udp_flags(pcb) ((pcb)->flags)
diff --git a/src/include/netif/etharp.h b/src/include/netif/etharp.h
index 0f8facca..307d1f64 100644
--- a/src/include/netif/etharp.h
+++ b/src/include/netif/etharp.h
@@ -196,11 +196,11 @@ struct etharp_q_entry {
 
 #define etharp_init() /* Compatibility define, no init needed. */
 void etharp_tmr(void);
-s8_t etharp_find_addr(struct netif *netif, ip_addr_t *ipaddr,
-         struct eth_addr **eth_ret, ip_addr_t **ip_ret);
-err_t etharp_output(struct netif *netif, struct pbuf *q, ip_addr_t *ipaddr);
-err_t etharp_query(struct netif *netif, ip_addr_t *ipaddr, struct pbuf *q);
-err_t etharp_request(struct netif *netif, ip_addr_t *ipaddr);
+s8_t etharp_find_addr(struct netif *netif, const ip_addr_t *ipaddr,
+         struct eth_addr **eth_ret, const ip_addr_t **ip_ret);
+err_t etharp_output(struct netif *netif, struct pbuf *q, const ip_addr_t *ipaddr);
+err_t etharp_query(struct netif *netif, const ip_addr_t *ipaddr, struct pbuf *q);
+err_t etharp_request(struct netif *netif, const ip_addr_t *ipaddr);
 /** For Ethernet network interfaces, we might want to send "gratuitous ARP";
  *  this is an ARP packet sent by a node in order to spontaneously cause other
  *  nodes to update an entry in their ARP cache.
@@ -209,8 +209,8 @@ err_t etharp_request(struct netif *netif, ip_addr_t *ipaddr);
 void etharp_cleanup_netif(struct netif *netif);
 
 #if ETHARP_SUPPORT_STATIC_ENTRIES
-err_t etharp_add_static_entry(ip_addr_t *ipaddr, struct eth_addr *ethaddr);
-err_t etharp_remove_static_entry(ip_addr_t *ipaddr);
+err_t etharp_add_static_entry(const ip_addr_t *ipaddr, struct eth_addr *ethaddr);
+err_t etharp_remove_static_entry(const ip_addr_t *ipaddr);
 #endif /* ETHARP_SUPPORT_STATIC_ENTRIES */
 
 #if LWIP_AUTOIP
diff --git a/src/netif/etharp.c b/src/netif/etharp.c
index 037cc683..05b2842b 100644
--- a/src/netif/etharp.c
+++ b/src/netif/etharp.c
@@ -264,7 +264,7 @@ etharp_tmr(void)
  * entry is found or could be recycled.
  */
 static s8_t
-etharp_find_entry(ip_addr_t *ipaddr, u8_t flags)
+etharp_find_entry(const ip_addr_t *ipaddr, u8_t flags)
 {
   s8_t old_pending = ARP_TABLE_SIZE, old_stable = ARP_TABLE_SIZE;
   s8_t empty = ARP_TABLE_SIZE;
@@ -462,7 +462,7 @@ etharp_send_ip(struct netif *netif, struct pbuf *p, struct eth_addr *src, struct
  * @see pbuf_free()
  */
 static err_t
-etharp_update_arp_entry(struct netif *netif, ip_addr_t *ipaddr, struct eth_addr *ethaddr, u8_t flags)
+etharp_update_arp_entry(struct netif *netif, const ip_addr_t *ipaddr, struct eth_addr *ethaddr, u8_t flags)
 {
   s8_t i;
   LWIP_ASSERT("netif->hwaddr_len == ETHARP_HWADDR_LEN", netif->hwaddr_len == ETHARP_HWADDR_LEN);
@@ -540,7 +540,7 @@ etharp_update_arp_entry(struct netif *netif, ip_addr_t *ipaddr, struct eth_addr
  * @return @see return values of etharp_add_static_entry
  */
 err_t
-etharp_add_static_entry(ip_addr_t *ipaddr, struct eth_addr *ethaddr)
+etharp_add_static_entry(const ip_addr_t *ipaddr, struct eth_addr *ethaddr)
 {
   struct netif *netif;
   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_add_static_entry: %"U16_F".%"U16_F".%"U16_F".%"U16_F" - %02"X16_F":%02"X16_F":%02"X16_F":%02"X16_F":%02"X16_F":%02"X16_F"\n",
@@ -565,7 +565,7 @@ etharp_add_static_entry(ip_addr_t *ipaddr, struct eth_addr *ethaddr)
  *         ERR_ARG: entry wasn't a static entry but a dynamic one
  */
 err_t
-etharp_remove_static_entry(ip_addr_t *ipaddr)
+etharp_remove_static_entry(const ip_addr_t *ipaddr)
 {
   s8_t i;
   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_remove_static_entry: %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
@@ -617,8 +617,8 @@ void etharp_cleanup_netif(struct netif *netif)
  * @return table index if found, -1 otherwise
  */
 s8_t
-etharp_find_addr(struct netif *netif, ip_addr_t *ipaddr,
-         struct eth_addr **eth_ret, ip_addr_t **ip_ret)
+etharp_find_addr(struct netif *netif, const ip_addr_t *ipaddr,
+         struct eth_addr **eth_ret, const ip_addr_t **ip_ret)
 {
   s8_t i;
 
@@ -893,11 +893,11 @@ etharp_output_to_arp_index(struct netif *netif, struct pbuf *q, u8_t arp_idx)
  * or the return type of either etharp_query() or etharp_send_ip().
  */
 err_t
-etharp_output(struct netif *netif, struct pbuf *q, ip_addr_t *ipaddr)
+etharp_output(struct netif *netif, struct pbuf *q, const ip_addr_t *ipaddr)
 {
   struct eth_addr *dest;
   struct eth_addr mcastaddr;
-  ip_addr_t *dst_addr = ipaddr;
+  const ip_addr_t *dst_addr = ipaddr;
 
   LWIP_ASSERT("netif != NULL", netif != NULL);
   LWIP_ASSERT("q != NULL", q != NULL);
@@ -1045,7 +1045,7 @@ etharp_output(struct netif *netif, struct pbuf *q, ip_addr_t *ipaddr)
  *
  */
 err_t
-etharp_query(struct netif *netif, ip_addr_t *ipaddr, struct pbuf *q)
+etharp_query(struct netif *netif, const ip_addr_t *ipaddr, struct pbuf *q)
 {
   struct eth_addr * srcaddr = (struct eth_addr *)netif->hwaddr;
   err_t result = ERR_MEM;
@@ -1326,7 +1326,7 @@ etharp_raw(struct netif *netif, const struct eth_addr *ethsrc_addr,
  *         any other err_t on failure
  */
 err_t
-etharp_request(struct netif *netif, ip_addr_t *ipaddr)
+etharp_request(struct netif *netif, const ip_addr_t *ipaddr)
 {
   LWIP_DEBUGF(ETHARP_DEBUG | LWIP_DBG_TRACE, ("etharp_request: sending ARP request.\n"));
   return etharp_raw(netif, (struct eth_addr *)netif->hwaddr, &ethbroadcast,