diff --git a/ext/lwip/CHANGELOG b/ext/lwip/CHANGELOG
index 9f5cda9..3b47ec2 100755
--- a/ext/lwip/CHANGELOG
+++ b/ext/lwip/CHANGELOG
@@ -4,6 +4,22 @@ HISTORY
 
   * [Enter new changes just after this line - do not remove this line]
 
+(STABLE-2.0.3)
+
+  ++ Bugfixes:
+
+  2017-09-11: Simon Goldschmidt
+  * tcp_in.c: fix bug #51937 (leaking tcp_pcbs on passive close with unacked data)
+
+  2017-08-02: Abroz Bizjak/Simon Goldschmidt
+  * multiple fixes in IPv4 reassembly (leading to corrupted datagrams received)
+  
+  2017-03-30: Simon Goldschmidt
+  * dhcp.c: return ERR_VAL instead of asserting on offset-out-of-pbuf
+
+  2017-03-23: Dirk Ziegelmeier
+  * dhcp.h: fix bug #50618 (dhcp_remove_struct() macro does not work)
+
 (STABLE-2.0.2)
 
   ++ New features:
@@ -13,6 +29,9 @@ HISTORY
     We now have a #define for a header file name that is #included in every .c
     file that provides hooks.
 
+  2017-02-10: Simon Goldschmidt
+  * tcp_close does not fail on memory error (instead, FIN is sent from tcp_tmr)
+
   ++ Bugfixes:
 
   2017-03-08
diff --git a/ext/lwip/UPGRADING b/ext/lwip/UPGRADING
index e32150a..89267ae 100755
--- a/ext/lwip/UPGRADING
+++ b/ext/lwip/UPGRADING
@@ -1,235 +1,243 @@
-This file lists major changes between release versions that require
-ports or applications to be changed. Use it to update a port or an
-application written for an older version of lwIP to correctly work
-with newer versions.
-
-
-(git master)
-
-  * [Enter new changes just after this line - do not remove this line]
-
+This file lists major changes between release versions that require
+ports or applications to be changed. Use it to update a port or an
+application written for an older version of lwIP to correctly work
+with newer versions.
+
+
+(git master)
+
+  * [Enter new changes just after this line - do not remove this line]
+
+(2.0.2)
+
+  ++ Application changes:
+
+  * slipif: The way to pass serial port number has changed. netif->num is not
+    supported any more, netif->state is interpreted as an u8_t port number now
+    (it's not a POINTER to an u8_t any more!)
+
 (2.0.1)
 
-  ++ Application changes:
-
-  * UDP does NOT receive multicast traffic from ALL netifs on an UDP PCB bound to a specific
-    netif any more. Users need to bind to IP_ADDR_ANY to receive multicast traffic and compare 
-    ip_current_netif() to the desired netif for every packet.
-    See bug #49662 for an explanation.
-
-(2.0.0)
-
-  ++ Application changes:
-
-  * Changed netif "up" flag handling to be an administrative flag (as opposed to the previous meaning of
-    "ip4-address-valid", a netif will now not be used for transmission if not up) -> even a DHCP netif
-    has to be set "up" before starting the DHCP client
-  * Added IPv6 support (dual-stack or IPv4/IPv6 only)
-  * Changed ip_addr_t to be a union in dual-stack mode (use ip4_addr_t where referring to IPv4 only).
-  * Major rewrite of SNMP (added MIB parser that creates code stubs for custom MIBs);
-    supports SNMPv2c (experimental v3 support)
-  * Moved some core applications from contrib repository to src/apps (and include/lwip/apps)
-
-  +++ Raw API:
-    * Changed TCP listen backlog: removed tcp_accepted(), added the function pair tcp_backlog_delayed()/
-      tcp_backlog_accepted() to explicitly delay backlog handling on a connection pcb
-
-  +++ Socket API:
-    * Added an implementation for posix sendmsg()
-    * Added LWIP_FIONREAD_LINUXMODE that makes ioctl/FIONREAD return the size of the next pending datagram
-
-  ++ Port changes
-
-  +++ new files:
-    * MANY new and moved files! 
-    * Added src/Filelists.mk for use in Makefile projects
-    * Continued moving stack-internal parts from abc.h to abc_priv.h in sub-folder "priv"
-      to let abc.h only contain the actual application programmer's API
-
-  +++ sys layer:
-    * Made LWIP_TCPIP_CORE_LOCKING==1 the default as it usually performs better than
-      the traditional message passing (although with LWIP_COMPAT_MUTEX you are still
-      open to priority inversion, so this is not recommended any more)
-    * Added LWIP_NETCONN_SEM_PER_THREAD to use one "op_completed" semaphore per thread
-      instead of using one per netconn (these semaphores are used even with core locking
-      enabled as some longer lasting functions like big writes still need to delay)
-    * Added generalized abstraction for itoa(), strnicmp(), stricmp() and strnstr()
-      in def.h (to be overridden in cc.h) instead of config 
-      options for netbiosns, httpd, dns, etc. ...
-    * New abstraction for hton* and ntoh* functions in def.h.
-      To override them, use the following in cc.h: 
-      #define lwip_htons(x) <your_htons>
-      #define lwip_htonl(x) <your_htonl>
-
-  +++ new options:
-     * TODO
-
-  +++ new pools:
-     * Added LWIP_MEMPOOL_* (declare/init/alloc/free) to declare private memp pools
-       that share memp.c code but do not have to be made global via lwippools.h
-     * Added pools for IPv6, MPU_COMPATIBLE, dns-api, netif-api, etc.
-     * added hook LWIP_HOOK_MEMP_AVAILABLE() to get informed when a memp pool was empty and an item
-       is now available
-
-  * Signature of LWIP_HOOK_VLAN_SET macro was changed
-
-  * LWIP_DECLARE_MEMORY_ALIGNED() may be used to declare aligned memory buffers (mem/memp)
-    or to move buffers to dedicated memory using compiler attributes
-
-  * Standard C headers are used to define sized types and printf formatters
-    (disable by setting LWIP_NO_STDINT_H=1 or LWIP_NO_INTTYPES_H=1 if your compiler
-    does not support these)
-
-
-  ++ Major bugfixes/improvements
-
-  * Added IPv6 support (dual-stack or IPv4/IPv6 only)
-  * Major rewrite of PPP (incl. keep-up with apache pppd)
-    see doc/ppp.txt for an upgrading how-to
-  * Major rewrite of SNMP (incl. MIB parser)
-  * Fixed timing issues that might have lead to losing a DHCP lease
-  * Made rx processing path more robust against crafted errors
-  * TCP window scaling support
-  * modification of api modules to support FreeRTOS-MPU (don't pass stack-pointers to other threads)
-  * made DNS client more robust
-  * support PBUF_REF for RX packets
-  * LWIP_NETCONN_FULLDUPLEX allows netconn/sockets to be used for reading/writing from separate
-    threads each (needs LWIP_NETCONN_SEM_PER_THREAD)
-  * Moved and reordered stats (mainly memp/mib2)
-
-(1.4.0)
-
-  ++ Application changes:
-
-  * Replaced struct ip_addr by typedef ip_addr_t (struct ip_addr is kept for
-    compatibility to old applications, but will be removed in the future).
-
-  * Renamed mem_realloc() to mem_trim() to prevent confusion with realloc()
-
-  +++ Raw API:
-    * Changed the semantics of tcp_close() (since it was rather a
-      shutdown before): Now the application does *NOT* get any calls to the recv
-      callback (aside from NULL/closed) after calling tcp_close()
-
-    * When calling tcp_abort() from a raw API TCP callback function,
-      make sure you return ERR_ABRT to prevent accessing unallocated memory.
-      (ERR_ABRT now means the applicaiton has called tcp_abort!)
-
-  +++ Netconn API:
-    * Changed netconn_receive() and netconn_accept() to return
-      err_t, not a pointer to new data/netconn.
-
-  +++ Socket API:
-    * LWIP_SO_RCVTIMEO: when accept() or recv() time out, they
-      now set errno to EWOULDBLOCK/EAGAIN, not ETIMEDOUT.
-
-    * Added a minimal version of posix fctl() to have a
-      standardised way to set O_NONBLOCK for nonblocking sockets.
-
-  +++ all APIs:
-    * correctly implemented SO(F)_REUSEADDR
-
-  ++ Port changes
-
-  +++ new files:
-
-    * Added 4 new files: def.c, timers.c, timers.h, tcp_impl.h:
-
-    * Moved stack-internal parts of tcp.h to tcp_impl.h, tcp.h now only contains
-      the actual application programmer's API
-  
-    * Separated timer implementation from sys.h/.c, moved to timers.h/.c;
-      Added timer implementation for NO_SYS==1, set NO_SYS_NO_TIMERS==1 if you
-      still want to use your own timer implementation for NO_SYS==0 (as before).
-
-  +++ sys layer:
-
-    * Converted mbox- and semaphore-functions to take pointers to sys_mbox_t/
-      sys_sem_t;
-
-    * Converted sys_mbox_new/sys_sem_new to take pointers and return err_t;
-
-    * Added Mutex concept in sys_arch (define LWIP_COMPAT_MUTEX to let sys.h use
-      binary semaphores instead of mutexes - as before)
-
-  +++ new options:
-
-     * Don't waste memory when chaining segments, added option TCP_OVERSIZE to
-       prevent creating many small pbufs when calling tcp_write with many small
-       blocks of data. Instead, pbufs are allocated larger than needed and the
-       space is used for later calls to tcp_write.
-
-     * Added LWIP_NETIF_TX_SINGLE_PBUF to always copy to try to create single pbufs
-       in tcp_write/udp_send.
-
-    * Added an additional option LWIP_ETHERNET to support ethernet without ARP
-      (necessary for pure PPPoE)
-
-    * Add MEMP_SEPARATE_POOLS to place memory pools in separate arrays. This may
-      be used to place these pools into user-defined memory by using external
-      declaration.
-
-    * Added TCP_SNDQUEUELOWAT corresponding to TCP_SNDLOWAT
-
-  +++ new pools:
-
-     * Netdb uses a memp pool for allocating memory when getaddrinfo() is called,
-       so MEMP_NUM_NETDB has to be set accordingly.
-
-     * DNS_LOCAL_HOSTLIST_IS_DYNAMIC uses a memp pool instead of the heap, so
-       MEMP_NUM_LOCALHOSTLIST has to be set accordingly.
-
-     * Snmp-agent uses a memp pools instead of the heap, so MEMP_NUM_SNMP_* have
-       to be set accordingly.
-
-     * PPPoE uses a MEMP pool instead of the heap, so MEMP_NUM_PPPOE_INTERFACES
-       has to be set accordingly
-
-  * Integrated loopif into netif.c - loopif does not have to be created by the
-    port any more, just define LWIP_HAVE_LOOPIF to 1.
-
-  * Added define LWIP_RAND() for lwip-wide randomization (needs to be defined
-    in cc.h, e.g. used by igmp)
-
-  * Added printf-formatter X8_F to printf u8_t as hex
-
-  * The heap now may be moved to user-defined memory by defining
-    LWIP_RAM_HEAP_POINTER as a void pointer to that memory's address
-
-  * added autoip_set_struct() and dhcp_set_struct() to let autoip and dhcp work
-    with user-allocated structs instead of calling mem_malloc
-
-  * Added const char* name to mem- and memp-stats for easier debugging.
-
-  * Calculate the TCP/UDP checksum while copying to only fetch data once:
-    Define LWIP_CHKSUM_COPY to a memcpy-like function that returns the checksum
-
-  * Added SO_REUSE_RXTOALL to pass received UDP broadcast/multicast packets to
-    more than one pcb.
-
-  * Changed the semantics of ARP_QUEUEING==0: ARP_QUEUEING now cannot be turned
-    off any more, if this is set to 0, only one packet (the most recent one) is
-    queued (like demanded by RFC 1122).
-
-  
-  ++ Major bugfixes/improvements
-
-  * Implemented tcp_shutdown() to only shut down one end of a connection
-  * Implemented shutdown() at socket- and netconn-level
-  * Added errorset support to select() + improved select speed overhead
-  * Merged pppd to v2.3.11 (including some backported bugfixes from 2.4.x)
-  * Added timer implementation for NO_SYS==1 (may be disabled with NO_SYS_NO_TIMERS==1
-  * Use macros defined in ip_addr.h to work with IP addresses
-  * Implemented many nonblocking socket/netconn functions
-  * Fixed ARP input processing: only add a new entry if a request was directed as us
-  * mem_realloc() to mem_trim() to prevent confusion with realloc()
-  * Some improvements for AutoIP (don't route/forward link-local addresses, don't break
-    existing connections when assigning a routable address)
-  * Correctly handle remote side overrunning our rcv_wnd in ooseq case
-  * Removed packing from ip_addr_t, the packed version is now only used in protocol headers
-  * Corrected PBUF_POOL_BUFSIZE for ports where ETH_PAD_SIZE > 0
-  * Added support for static ARP table entries
-
-(STABLE-1.3.2)
-
-  * initial version of this file
+  ++ Application changes:
+
+  * UDP does NOT receive multicast traffic from ALL netifs on an UDP PCB bound to a specific
+    netif any more. Users need to bind to IP_ADDR_ANY to receive multicast traffic and compare 
+    ip_current_netif() to the desired netif for every packet.
+    See bug #49662 for an explanation.
+
+(2.0.0)
+
+  ++ Application changes:
+
+  * Changed netif "up" flag handling to be an administrative flag (as opposed to the previous meaning of
+    "ip4-address-valid", a netif will now not be used for transmission if not up) -> even a DHCP netif
+    has to be set "up" before starting the DHCP client
+  * Added IPv6 support (dual-stack or IPv4/IPv6 only)
+  * Changed ip_addr_t to be a union in dual-stack mode (use ip4_addr_t where referring to IPv4 only).
+  * Major rewrite of SNMP (added MIB parser that creates code stubs for custom MIBs);
+    supports SNMPv2c (experimental v3 support)
+  * Moved some core applications from contrib repository to src/apps (and include/lwip/apps)
+
+  +++ Raw API:
+    * Changed TCP listen backlog: removed tcp_accepted(), added the function pair tcp_backlog_delayed()/
+      tcp_backlog_accepted() to explicitly delay backlog handling on a connection pcb
+
+  +++ Socket API:
+    * Added an implementation for posix sendmsg()
+    * Added LWIP_FIONREAD_LINUXMODE that makes ioctl/FIONREAD return the size of the next pending datagram
+
+  ++ Port changes
+
+  +++ new files:
+    * MANY new and moved files! 
+    * Added src/Filelists.mk for use in Makefile projects
+    * Continued moving stack-internal parts from abc.h to abc_priv.h in sub-folder "priv"
+      to let abc.h only contain the actual application programmer's API
+
+  +++ sys layer:
+    * Made LWIP_TCPIP_CORE_LOCKING==1 the default as it usually performs better than
+      the traditional message passing (although with LWIP_COMPAT_MUTEX you are still
+      open to priority inversion, so this is not recommended any more)
+    * Added LWIP_NETCONN_SEM_PER_THREAD to use one "op_completed" semaphore per thread
+      instead of using one per netconn (these semaphores are used even with core locking
+      enabled as some longer lasting functions like big writes still need to delay)
+    * Added generalized abstraction for itoa(), strnicmp(), stricmp() and strnstr()
+      in def.h (to be overridden in cc.h) instead of config 
+      options for netbiosns, httpd, dns, etc. ...
+    * New abstraction for hton* and ntoh* functions in def.h.
+      To override them, use the following in cc.h: 
+      #define lwip_htons(x) <your_htons>
+      #define lwip_htonl(x) <your_htonl>
+
+  +++ new options:
+     * TODO
+
+  +++ new pools:
+     * Added LWIP_MEMPOOL_* (declare/init/alloc/free) to declare private memp pools
+       that share memp.c code but do not have to be made global via lwippools.h
+     * Added pools for IPv6, MPU_COMPATIBLE, dns-api, netif-api, etc.
+     * added hook LWIP_HOOK_MEMP_AVAILABLE() to get informed when a memp pool was empty and an item
+       is now available
+
+  * Signature of LWIP_HOOK_VLAN_SET macro was changed
+
+  * LWIP_DECLARE_MEMORY_ALIGNED() may be used to declare aligned memory buffers (mem/memp)
+    or to move buffers to dedicated memory using compiler attributes
+
+  * Standard C headers are used to define sized types and printf formatters
+    (disable by setting LWIP_NO_STDINT_H=1 or LWIP_NO_INTTYPES_H=1 if your compiler
+    does not support these)
+
+
+  ++ Major bugfixes/improvements
+
+  * Added IPv6 support (dual-stack or IPv4/IPv6 only)
+  * Major rewrite of PPP (incl. keep-up with apache pppd)
+    see doc/ppp.txt for an upgrading how-to
+  * Major rewrite of SNMP (incl. MIB parser)
+  * Fixed timing issues that might have lead to losing a DHCP lease
+  * Made rx processing path more robust against crafted errors
+  * TCP window scaling support
+  * modification of api modules to support FreeRTOS-MPU (don't pass stack-pointers to other threads)
+  * made DNS client more robust
+  * support PBUF_REF for RX packets
+  * LWIP_NETCONN_FULLDUPLEX allows netconn/sockets to be used for reading/writing from separate
+    threads each (needs LWIP_NETCONN_SEM_PER_THREAD)
+  * Moved and reordered stats (mainly memp/mib2)
+
+(1.4.0)
+
+  ++ Application changes:
+
+  * Replaced struct ip_addr by typedef ip_addr_t (struct ip_addr is kept for
+    compatibility to old applications, but will be removed in the future).
+
+  * Renamed mem_realloc() to mem_trim() to prevent confusion with realloc()
+
+  +++ Raw API:
+    * Changed the semantics of tcp_close() (since it was rather a
+      shutdown before): Now the application does *NOT* get any calls to the recv
+      callback (aside from NULL/closed) after calling tcp_close()
+
+    * When calling tcp_abort() from a raw API TCP callback function,
+      make sure you return ERR_ABRT to prevent accessing unallocated memory.
+      (ERR_ABRT now means the applicaiton has called tcp_abort!)
+
+  +++ Netconn API:
+    * Changed netconn_receive() and netconn_accept() to return
+      err_t, not a pointer to new data/netconn.
+
+  +++ Socket API:
+    * LWIP_SO_RCVTIMEO: when accept() or recv() time out, they
+      now set errno to EWOULDBLOCK/EAGAIN, not ETIMEDOUT.
+
+    * Added a minimal version of posix fctl() to have a
+      standardised way to set O_NONBLOCK for nonblocking sockets.
+
+  +++ all APIs:
+    * correctly implemented SO(F)_REUSEADDR
+
+  ++ Port changes
+
+  +++ new files:
+
+    * Added 4 new files: def.c, timers.c, timers.h, tcp_impl.h:
+
+    * Moved stack-internal parts of tcp.h to tcp_impl.h, tcp.h now only contains
+      the actual application programmer's API
+  
+    * Separated timer implementation from sys.h/.c, moved to timers.h/.c;
+      Added timer implementation for NO_SYS==1, set NO_SYS_NO_TIMERS==1 if you
+      still want to use your own timer implementation for NO_SYS==0 (as before).
+
+  +++ sys layer:
+
+    * Converted mbox- and semaphore-functions to take pointers to sys_mbox_t/
+      sys_sem_t;
+
+    * Converted sys_mbox_new/sys_sem_new to take pointers and return err_t;
+
+    * Added Mutex concept in sys_arch (define LWIP_COMPAT_MUTEX to let sys.h use
+      binary semaphores instead of mutexes - as before)
+
+  +++ new options:
+
+     * Don't waste memory when chaining segments, added option TCP_OVERSIZE to
+       prevent creating many small pbufs when calling tcp_write with many small
+       blocks of data. Instead, pbufs are allocated larger than needed and the
+       space is used for later calls to tcp_write.
+
+     * Added LWIP_NETIF_TX_SINGLE_PBUF to always copy to try to create single pbufs
+       in tcp_write/udp_send.
+
+    * Added an additional option LWIP_ETHERNET to support ethernet without ARP
+      (necessary for pure PPPoE)
+
+    * Add MEMP_SEPARATE_POOLS to place memory pools in separate arrays. This may
+      be used to place these pools into user-defined memory by using external
+      declaration.
+
+    * Added TCP_SNDQUEUELOWAT corresponding to TCP_SNDLOWAT
+
+  +++ new pools:
+
+     * Netdb uses a memp pool for allocating memory when getaddrinfo() is called,
+       so MEMP_NUM_NETDB has to be set accordingly.
+
+     * DNS_LOCAL_HOSTLIST_IS_DYNAMIC uses a memp pool instead of the heap, so
+       MEMP_NUM_LOCALHOSTLIST has to be set accordingly.
+
+     * Snmp-agent uses a memp pools instead of the heap, so MEMP_NUM_SNMP_* have
+       to be set accordingly.
+
+     * PPPoE uses a MEMP pool instead of the heap, so MEMP_NUM_PPPOE_INTERFACES
+       has to be set accordingly
+
+  * Integrated loopif into netif.c - loopif does not have to be created by the
+    port any more, just define LWIP_HAVE_LOOPIF to 1.
+
+  * Added define LWIP_RAND() for lwip-wide randomization (needs to be defined
+    in cc.h, e.g. used by igmp)
+
+  * Added printf-formatter X8_F to printf u8_t as hex
+
+  * The heap now may be moved to user-defined memory by defining
+    LWIP_RAM_HEAP_POINTER as a void pointer to that memory's address
+
+  * added autoip_set_struct() and dhcp_set_struct() to let autoip and dhcp work
+    with user-allocated structs instead of calling mem_malloc
+
+  * Added const char* name to mem- and memp-stats for easier debugging.
+
+  * Calculate the TCP/UDP checksum while copying to only fetch data once:
+    Define LWIP_CHKSUM_COPY to a memcpy-like function that returns the checksum
+
+  * Added SO_REUSE_RXTOALL to pass received UDP broadcast/multicast packets to
+    more than one pcb.
+
+  * Changed the semantics of ARP_QUEUEING==0: ARP_QUEUEING now cannot be turned
+    off any more, if this is set to 0, only one packet (the most recent one) is
+    queued (like demanded by RFC 1122).
+
+  
+  ++ Major bugfixes/improvements
+
+  * Implemented tcp_shutdown() to only shut down one end of a connection
+  * Implemented shutdown() at socket- and netconn-level
+  * Added errorset support to select() + improved select speed overhead
+  * Merged pppd to v2.3.11 (including some backported bugfixes from 2.4.x)
+  * Added timer implementation for NO_SYS==1 (may be disabled with NO_SYS_NO_TIMERS==1
+  * Use macros defined in ip_addr.h to work with IP addresses
+  * Implemented many nonblocking socket/netconn functions
+  * Fixed ARP input processing: only add a new entry if a request was directed as us
+  * mem_realloc() to mem_trim() to prevent confusion with realloc()
+  * Some improvements for AutoIP (don't route/forward link-local addresses, don't break
+    existing connections when assigning a routable address)
+  * Correctly handle remote side overrunning our rcv_wnd in ooseq case
+  * Removed packing from ip_addr_t, the packed version is now only used in protocol headers
+  * Corrected PBUF_POOL_BUFSIZE for ports where ETH_PAD_SIZE > 0
+  * Added support for static ARP table entries
+
+(STABLE-1.3.2)
+
+  * initial version of this file
diff --git a/ext/lwip/doc/NO_SYS_SampleCode.c b/ext/lwip/doc/NO_SYS_SampleCode.c
index e86d63e..fcc22c5 100755
--- a/ext/lwip/doc/NO_SYS_SampleCode.c
+++ b/ext/lwip/doc/NO_SYS_SampleCode.c
@@ -1,4 +1,5 @@
-void eth_mac_irq()
+void
+eth_mac_irq()
 {
   /* Service MAC IRQ here */
 
@@ -17,7 +18,8 @@ void eth_mac_irq()
   }
 }
 
-static err_t netif_output(struct netif *netif, struct pbuf *p)
+static err_t 
+netif_output(struct netif *netif, struct pbuf *p)
 {
   LINK_STATS_INC(link.xmit);
 
@@ -38,12 +40,14 @@ static err_t netif_output(struct netif *netif, struct pbuf *p)
   return ERR_OK;
 }
 
-static void netif_status_callback(struct netif *netif)
+static void 
+netif_status_callback(struct netif *netif)
 {
   printf("netif status changed %s\n", ip4addr_ntoa(netif_ip4_addr(netif)));
 }
 
-static err_t netif_init(struct netif *netif)
+static err_t 
+netif_init(struct netif *netif)
 {
   netif->linkoutput = netif_output;
   netif->output     = etharp_output;
@@ -58,7 +62,8 @@ static err_t netif_init(struct netif *netif)
   return ERR_OK;
 }
 
-void main(void)
+void 
+main(void)
 {
   struct netif netif;
 
@@ -74,7 +79,7 @@ void main(void)
   netif_set_up(&netif);
   
   /* Start DHCP and HTTPD */
-  dhcp_init();
+  dhcp_start(&netif );
   httpd_init();
 
   while(1) {
diff --git a/ext/lwip/src/api/api_msg.c b/ext/lwip/src/api/api_msg.c
index 971c8b1..a609017 100755
--- a/ext/lwip/src/api/api_msg.c
+++ b/ext/lwip/src/api/api_msg.c
@@ -177,14 +177,20 @@ recv_udp(void *arg, struct udp_pcb *pcb, struct pbuf *p,
   LWIP_ASSERT("recv_udp must have a pcb argument", pcb != NULL);
   LWIP_ASSERT("recv_udp must have an argument", arg != NULL);
   conn = (struct netconn *)arg;
+
+  if (conn == NULL) {
+    pbuf_free(p);
+    return;
+  }
+
   LWIP_ASSERT("recv_udp: recv for wrong pcb!", conn->pcb.udp == pcb);
 
 #if LWIP_SO_RCVBUF
   SYS_ARCH_GET(conn->recv_avail, recv_avail);
-  if ((conn == NULL) || !sys_mbox_valid(&conn->recvmbox) ||
+  if (!sys_mbox_valid(&conn->recvmbox) ||
       ((recv_avail + (int)(p->tot_len)) > conn->recv_bufsize)) {
 #else  /* LWIP_SO_RCVBUF */
-  if ((conn == NULL) || !sys_mbox_valid(&conn->recvmbox)) {
+  if (!sys_mbox_valid(&conn->recvmbox)) {
 #endif /* LWIP_SO_RCVBUF */
     pbuf_free(p);
     return;
@@ -471,8 +477,6 @@ accept_function(void *arg, struct tcp_pcb *newpcb, err_t err)
   struct netconn *newconn;
   struct netconn *conn = (struct netconn *)arg;
 
-  LWIP_DEBUGF(API_MSG_DEBUG, ("accept_function: newpcb->tate: %s\n", tcp_debug_state_str(newpcb->state)));
-
   if (conn == NULL) {
     return ERR_VAL;
   }
@@ -490,6 +494,8 @@ accept_function(void *arg, struct tcp_pcb *newpcb, err_t err)
     return ERR_VAL;
   }
 
+  LWIP_DEBUGF(API_MSG_DEBUG, ("accept_function: newpcb->tate: %s\n", tcp_debug_state_str(newpcb->state)));
+
   /* We have to set the callback here even though
    * the new socket is unknown. newconn->socket is marked as -1. */
   newconn = netconn_alloc(conn->type, conn->callback);
diff --git a/ext/lwip/src/api/err.c b/ext/lwip/src/api/err.c
index 997eb6c..cc3dabb 100755
--- a/ext/lwip/src/api/err.c
+++ b/ext/lwip/src/api/err.c
@@ -41,6 +41,7 @@
 #include "lwip/sys.h"
 
 #include <errno.h>
+//#include "lwip/errno.h"
 
 #if !NO_SYS
 /** Table to quickly map an lwIP error (err_t) to a socket error
diff --git a/ext/lwip/src/apps/mqtt/mqtt.c b/ext/lwip/src/apps/mqtt/mqtt.c
index 29a975e..565c34a 100755
--- a/ext/lwip/src/apps/mqtt/mqtt.c
+++ b/ext/lwip/src/apps/mqtt/mqtt.c
@@ -360,8 +360,9 @@ mqtt_take_request(struct mqtt_request_t **tail, u16_t pkt_id)
 static void
 mqtt_request_time_elapsed(struct mqtt_request_t **tail, u8_t t)
 {
-  struct mqtt_request_t *r = *tail;
+  struct mqtt_request_t *r;
   LWIP_ASSERT("mqtt_request_time_elapsed: tail != NULL", tail != NULL);
+  r = *tail;
   while (t > 0 && r != NULL) {
     if (t >= r->timeout_diff) {
       t -= (u8_t)r->timeout_diff;
diff --git a/ext/lwip/src/core/init.c b/ext/lwip/src/core/init.c
index 7d2cd38..5e50858 100755
--- a/ext/lwip/src/core/init.c
+++ b/ext/lwip/src/core/init.c
@@ -337,7 +337,7 @@ void
 lwip_init(void)
 {
 #ifndef LWIP_SKIP_CONST_CHECK
-  int a;
+  int a = 0;
   LWIP_UNUSED_ARG(a);
   LWIP_ASSERT("LWIP_CONST_CAST not implemented correctly. Check your lwIP port.", LWIP_CONST_CAST(void*, &a) == &a);
 #endif
diff --git a/ext/lwip/src/core/ipv4/dhcp.c b/ext/lwip/src/core/ipv4/dhcp.c
index 8f2d573..74f6b58 100755
--- a/ext/lwip/src/core/ipv4/dhcp.c
+++ b/ext/lwip/src/core/ipv4/dhcp.c
@@ -736,7 +736,7 @@ dhcp_start(struct netif *netif)
 
   /* no DHCP client attached yet? */
   if (dhcp == NULL) {
-    LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_start(): starting new DHCP client\n"));
+    LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_start(): mallocing new DHCP client\n"));
     dhcp = (struct dhcp *)mem_malloc(sizeof(struct dhcp));
     if (dhcp == NULL) {
       LWIP_DEBUGF(DHCP_DEBUG | LWIP_DBG_TRACE, ("dhcp_start(): could not allocate dhcp\n"));
@@ -1500,7 +1500,7 @@ again:
   offset_max = options_idx_max;
   options = (u8_t*)q->payload;
   /* at least 1 byte to read and no end marker, then at least 3 bytes to read? */
-  while ((q != NULL) && (options[offset] != DHCP_OPTION_END) && (offset < offset_max)) {
+  while ((q != NULL) && (offset < offset_max) && (options[offset] != DHCP_OPTION_END)) {
     u8_t op = options[offset];
     u8_t len;
     u8_t decode_len = 0;
@@ -1617,7 +1617,7 @@ decode_next:
       offset_max -= q->len;
       if ((offset < offset_max) && offset_max) {
         q = q->next;
-        LWIP_ASSERT("next pbuf was null", q);
+        LWIP_ERROR("next pbuf was null", q != NULL, return ERR_VAL;);
         options = (u8_t*)q->payload;
       } else {
         /* We've run out of bytes, probably no end marker. Don't proceed. */
@@ -1832,7 +1832,7 @@ dhcp_create_msg(struct netif *netif, struct dhcp *dhcp, u8_t message_type)
            (dhcp->p_out->len >= sizeof(struct dhcp_msg)));
 
   /* DHCP_REQUEST should reuse 'xid' from DHCPOFFER */
-  if (message_type != DHCP_REQUEST) {
+  if ((message_type != DHCP_REQUEST) || (dhcp->state == DHCP_STATE_REBOOTING)) {
     /* reuse transaction identifier in retransmissions */
     if (dhcp->tries == 0) {
 #if DHCP_CREATE_RAND_XID && defined(LWIP_RAND)
@@ -1942,7 +1942,8 @@ dhcp_supplied_address(const struct netif *netif)
 {
   if ((netif != NULL) && (netif_dhcp_data(netif) != NULL)) {
     struct dhcp* dhcp = netif_dhcp_data(netif);
-    return (dhcp->state == DHCP_STATE_BOUND) || (dhcp->state == DHCP_STATE_RENEWING);
+    return (dhcp->state == DHCP_STATE_BOUND) || (dhcp->state == DHCP_STATE_RENEWING) ||
+           (dhcp->state == DHCP_STATE_REBINDING);
   }
   return 0;
 }
diff --git a/ext/lwip/src/core/ipv4/ip4_frag.c b/ext/lwip/src/core/ipv4/ip4_frag.c
index 61a24da..996c8be 100755
--- a/ext/lwip/src/core/ipv4/ip4_frag.c
+++ b/ext/lwip/src/core/ipv4/ip4_frag.c
@@ -79,6 +79,10 @@
 
 #define IP_REASS_FLAG_LASTFRAG 0x01
 
+#define IP_REASS_VALIDATE_TELEGRAM_FINISHED  1
+#define IP_REASS_VALIDATE_PBUF_QUEUED        0
+#define IP_REASS_VALIDATE_PBUF_DROPPED       -1
+
 /** This is a helper struct which holds the starting
  * offset and the ending offset of this fragment to
  * easily chain the fragments.
@@ -333,10 +337,11 @@ ip_reass_dequeue_datagram(struct ip_reassdata *ipr, struct ip_reassdata *prev)
  * fragment was received at least once).
  * @param ipr points to the reassembly state
  * @param new_p points to the pbuf for the current fragment
- * @return 0 if invalid, >0 otherwise
+ * @param is_last is 1 if this pbuf has MF==0 (ipr->flags not updated yet)
+ * @return see IP_REASS_VALIDATE_* defines
  */
 static int
-ip_reass_chain_frag_into_datagram_and_validate(struct ip_reassdata *ipr, struct pbuf *new_p)
+ip_reass_chain_frag_into_datagram_and_validate(struct ip_reassdata *ipr, struct pbuf *new_p, int is_last)
 {
   struct ip_reass_helper *iprh, *iprh_tmp, *iprh_prev=NULL;
   struct pbuf *q;
@@ -375,7 +380,18 @@ ip_reass_chain_frag_into_datagram_and_validate(struct ip_reassdata *ipr, struct
         }
 #endif /* IP_REASS_CHECK_OVERLAP */
         iprh_prev->next_pbuf = new_p;
+        if (iprh_prev->end != iprh->start) {
+          /* There is a fragment missing between the current
+           * and the previous fragment */
+          valid = 0;
+        }
       } else {
+#if IP_REASS_CHECK_OVERLAP
+        if (iprh->end > iprh_tmp->start) {
+          /* fragment overlaps with following, throw away */
+          goto freepbuf;
+        }
+#endif /* IP_REASS_CHECK_OVERLAP */
         /* fragment with the lowest offset */
         ipr->p = new_p;
       }
@@ -426,7 +442,7 @@ ip_reass_chain_frag_into_datagram_and_validate(struct ip_reassdata *ipr, struct
 
   /* At this point, the validation part begins: */
   /* If we already received the last fragment */
-  if ((ipr->flags & IP_REASS_FLAG_LASTFRAG) != 0) {
+  if (is_last || ((ipr->flags & IP_REASS_FLAG_LASTFRAG) != 0)) {
     /* and had no holes so far */
     if (valid) {
       /* then check if the rest of the fragments is here */
@@ -454,23 +470,21 @@ ip_reass_chain_frag_into_datagram_and_validate(struct ip_reassdata *ipr, struct
             ((struct ip_reass_helper*)ipr->p->payload) != iprh);
           LWIP_ASSERT("validate_datagram:next_pbuf!=NULL",
             iprh->next_pbuf == NULL);
-          LWIP_ASSERT("validate_datagram:datagram end!=datagram len",
-            iprh->end == ipr->datagram_len);
         }
       }
     }
     /* If valid is 0 here, there are some fragments missing in the middle
      * (since MF == 0 has already arrived). Such datagrams simply time out if
      * no more fragments are received... */
-    return valid;
+    return valid ? IP_REASS_VALIDATE_TELEGRAM_FINISHED : IP_REASS_VALIDATE_PBUF_QUEUED;
   }
   /* If we come here, not all fragments were received, yet! */
-  return 0; /* not yet valid! */
+  return IP_REASS_VALIDATE_PBUF_QUEUED; /* not yet valid! */
 #if IP_REASS_CHECK_OVERLAP
 freepbuf:
   ip_reass_pbufcount -= pbuf_clen(new_p);
   pbuf_free(new_p);
-  return 0;
+  return IP_REASS_VALIDATE_PBUF_DROPPED;
 #endif /* IP_REASS_CHECK_OVERLAP */
 }
 
@@ -488,6 +502,8 @@ ip4_reass(struct pbuf *p)
   struct ip_reassdata *ipr;
   struct ip_reass_helper *iprh;
   u16_t offset, len, clen;
+  int valid;
+  int is_last;
 
   IPFRAG_STATS_INC(ip_frag.recv);
   MIB2_STATS_INC(mib2.ipreasmreqds);
@@ -552,24 +568,41 @@ ip4_reass(struct pbuf *p)
       SMEMCPY(&ipr->iphdr, fraghdr, IP_HLEN);
     }
   }
-  /* Track the current number of pbufs current 'in-flight', in order to limit
-  the number of fragments that may be enqueued at any one time */
-  ip_reass_pbufcount += clen;
 
   /* At this point, we have either created a new entry or pointing
    * to an existing one */
 
   /* check for 'no more fragments', and update queue entry*/
-  if ((IPH_OFFSET(fraghdr) & PP_NTOHS(IP_MF)) == 0) {
+  is_last = (IPH_OFFSET(fraghdr) & PP_NTOHS(IP_MF)) == 0;
+  if (is_last) {
+    u16_t datagram_len = (u16_t)(offset + len);
+    if ((datagram_len < offset) || (datagram_len > (0xFFFF - IP_HLEN))) {
+      /* u16_t overflow, cannot handle this */
+      goto nullreturn;
+    }
+  }
+  /* find the right place to insert this pbuf */
+  /* @todo: trim pbufs if fragments are overlapping */
+  valid = ip_reass_chain_frag_into_datagram_and_validate(ipr, p, is_last);
+  if (valid == IP_REASS_VALIDATE_PBUF_DROPPED) {
+    goto nullreturn;
+  }
+  /* if we come here, the pbuf has been enqueued */
+
+  /* Track the current number of pbufs current 'in-flight', in order to limit
+     the number of fragments that may be enqueued at any one time
+     (overflow checked by testing against IP_REASS_MAX_PBUFS) */
+  ip_reass_pbufcount = (u16_t)(ip_reass_pbufcount + clen);
+  if (is_last) {
+    u16_t datagram_len = (u16_t)(offset + len);
+    ipr->datagram_len = datagram_len;
     ipr->flags |= IP_REASS_FLAG_LASTFRAG;
-    ipr->datagram_len = offset + len;
     LWIP_DEBUGF(IP_REASS_DEBUG,
      ("ip4_reass: last fragment seen, total len %"S16_F"\n",
       ipr->datagram_len));
   }
-  /* find the right place to insert this pbuf */
-  /* @todo: trim pbufs if fragments are overlapping */
-  if (ip_reass_chain_frag_into_datagram_and_validate(ipr, p)) {
+
+  if (valid == IP_REASS_VALIDATE_TELEGRAM_FINISHED) {
     struct ip_reassdata *ipr_prev;
     /* the totally last fragment (flag more fragments = 0) was received at least
      * once AND all fragments are received */
diff --git a/ext/lwip/src/core/netif.c b/ext/lwip/src/core/netif.c
index f3ff808..f16a0ff 100755
--- a/ext/lwip/src/core/netif.c
+++ b/ext/lwip/src/core/netif.c
@@ -849,7 +849,9 @@ netif_loop_output(struct netif *netif, struct pbuf *p)
      netif_poll(). */
 
   /* let last point to the last pbuf in chain r */
-  for (last = r; last->next != NULL; last = last->next);
+  for (last = r; last->next != NULL; last = last->next) {
+    /* nothing to do here, just get to the last pbuf */
+  }
 
   SYS_ARCH_PROTECT(lev);
   if (netif->loop_first != NULL) {
diff --git a/ext/lwip/src/core/tcp.c b/ext/lwip/src/core/tcp.c
index 697bc2d..fb95374 100755
--- a/ext/lwip/src/core/tcp.c
+++ b/ext/lwip/src/core/tcp.c
@@ -358,7 +358,6 @@ tcp_close_shutdown_fin(struct tcp_pcb *pcb)
   default:
     /* Has already been closed, do nothing. */
     return ERR_OK;
-    break;
   }
 
   if (err == ERR_OK) {
@@ -371,6 +370,12 @@ tcp_close_shutdown_fin(struct tcp_pcb *pcb)
   } else if (err == ERR_MEM) {
     /* Mark this pcb for closing. Closing is retried from tcp_tmr. */
     pcb->flags |= TF_CLOSEPEND;
+    /* We have to return ERR_OK from here to indicate to the callers that this
+       pcb should not be used any more as it will be freed soon via tcp_tmr.
+       This is OK here since sending FIN does not guarantee a time frime for
+       actually freeing the pcb, either (it is left in closure states for
+       remote ACK or timeout) */
+    return ERR_OK;
   }
   return err;
 }
@@ -408,8 +413,8 @@ tcp_close(struct tcp_pcb *pcb)
  * @ingroup tcp_raw
  * Causes all or part of a full-duplex connection of this PCB to be shut down.
  * This doesn't deallocate the PCB unless shutting down both sides!
- * Shutting down both sides is the same as calling tcp_close, so if it succeds,
- * the PCB should not be referenced any more.
+ * Shutting down both sides is the same as calling tcp_close, so if it succeds
+ * (i.e. returns ER_OK), the PCB must not be referenced any more!
  *
  * @param pcb PCB to shutdown
  * @param shut_rx shut down receive side if this is != 0
diff --git a/ext/lwip/src/core/tcp_in.c b/ext/lwip/src/core/tcp_in.c
index 1c5ab6b..17ceaff 100755
--- a/ext/lwip/src/core/tcp_in.c
+++ b/ext/lwip/src/core/tcp_in.c
@@ -89,6 +89,8 @@ static void tcp_parseopt(struct tcp_pcb *pcb);
 static void tcp_listen_input(struct tcp_pcb_listen *pcb);
 static void tcp_timewait_input(struct tcp_pcb *pcb);
 
+static int tcp_input_delayed_close(struct tcp_pcb *pcb);
+
 /**
  * The initial input processing of TCP. It verifies the TCP header, demultiplexes
  * the segment between the PCBs and passes it on to tcp_process(), which implements
@@ -404,17 +406,7 @@ tcp_input(struct pbuf *p, struct netif *inp)
           }
           recv_acked = 0;
         }
-        if (recv_flags & TF_CLOSED) {
-          /* The connection has been closed and we will deallocate the
-             PCB. */
-          if (!(pcb->flags & TF_RXCLOSED)) {
-            /* Connection closed although the application has only shut down the
-               tx side: call the PCB's err callback and indicate the closure to
-               ensure the application doesn't continue using the PCB. */
-            TCP_EVENT_ERR(pcb->state, pcb->errf, pcb->callback_arg, ERR_CLSD);
-          }
-          tcp_pcb_remove(&tcp_active_pcbs, pcb);
-          memp_free(MEMP_TCP_PCB, pcb);
+        if (tcp_input_delayed_close(pcb)) {
           goto aborted;
         }
 #if TCP_QUEUE_OOSEQ && LWIP_WND_SCALE
@@ -488,6 +480,9 @@ tcp_input(struct pbuf *p, struct netif *inp)
         }
 
         tcp_input_pcb = NULL;
+        if (tcp_input_delayed_close(pcb)) {
+          goto aborted;
+        }
         /* Try to send something out. */
         tcp_output(pcb);
 #if TCP_INPUT_DEBUG
@@ -532,6 +527,30 @@ dropped:
   pbuf_free(p);
 }
 
+/** Called from tcp_input to check for TF_CLOSED flag. This results in closing
+ * and deallocating a pcb at the correct place to ensure noone references it
+ * any more.
+ * @returns 1 if the pcb has been closed and deallocated, 0 otherwise
+ */
+static int
+tcp_input_delayed_close(struct tcp_pcb *pcb)
+{
+  if (recv_flags & TF_CLOSED) {
+    /* The connection has been closed and we will deallocate the
+        PCB. */
+    if (!(pcb->flags & TF_RXCLOSED)) {
+      /* Connection closed although the application has only shut down the
+          tx side: call the PCB's err callback and indicate the closure to
+          ensure the application doesn't continue using the PCB. */
+      TCP_EVENT_ERR(pcb->state, pcb->errf, pcb->callback_arg, ERR_CLSD);
+    }
+    tcp_pcb_remove(&tcp_active_pcbs, pcb);
+    memp_free(MEMP_TCP_PCB, pcb);
+    return 1;
+  }
+  return 0;
+}
+
 /**
  * Called by tcp_input() when a segment arrives for a listening
  * connection (from tcp_input()).
@@ -1749,11 +1768,11 @@ tcp_parseopt(struct tcp_pcb *pcb)
           LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_parseopt: bad length\n"));
           return;
         }
+        /* An WND_SCALE option with the right option length. */
+        data = tcp_getoptbyte();
         /* If syn was received with wnd scale option,
            activate wnd scale opt, but only if this is not a retransmission */
         if ((flags & TCP_SYN) && !(pcb->flags & TF_WND_SCALE)) {
-          /* An WND_SCALE option with the right option length. */
-          data = tcp_getoptbyte();
           pcb->snd_scale = data;
           if (pcb->snd_scale > 14U) {
             pcb->snd_scale = 14U;
diff --git a/ext/lwip/src/core/timeouts.c b/ext/lwip/src/core/timeouts.c
index 40749f9..5c9b29d 100755
--- a/ext/lwip/src/core/timeouts.c
+++ b/ext/lwip/src/core/timeouts.c
@@ -176,7 +176,7 @@ void sys_timeouts_init(void)
 {
   size_t i;
   /* tcp_tmr() at index 0 is started on demand */
-  for (i = 1; i < LWIP_ARRAYSIZE(lwip_cyclic_timers); i++) {
+  for (i = (LWIP_TCP ? 1 : 0); i < LWIP_ARRAYSIZE(lwip_cyclic_timers); i++) {
     /* we have to cast via size_t to get rid of const warning
       (this is OK as cyclic_timer() casts back to const* */
     sys_timeout(lwip_cyclic_timers[i].interval_ms, cyclic_timer, LWIP_CONST_CAST(void*, &lwip_cyclic_timers[i]));
diff --git a/ext/lwip/src/include/lwip/arch.h b/ext/lwip/src/include/lwip/arch.h
index 58b9d6e..f366ab5 100755
--- a/ext/lwip/src/include/lwip/arch.h
+++ b/ext/lwip/src/include/lwip/arch.h
@@ -76,8 +76,7 @@
  * systems, this should be defined to something less resource-consuming.
  */
 #ifndef LWIP_PLATFORM_DIAG
-#include "Debug.hpp"
-#define LWIP_PLATFORM_DIAG(x) printf(x);
+#define LWIP_PLATFORM_DIAG(x) do {printf x;} while(0)
 #include <stdio.h>
 #include <stdlib.h>
 #endif
diff --git a/ext/lwip/src/include/lwip/def.h b/ext/lwip/src/include/lwip/def.h
index 12b143c..2db7522 100755
--- a/ext/lwip/src/include/lwip/def.h
+++ b/ext/lwip/src/include/lwip/def.h
@@ -91,14 +91,6 @@ u32_t lwip_htonl(u32_t x);
 #endif
 #define lwip_ntohl(x) lwip_htonl(x)
 
-/* Provide usual function names as macros for users, but this can be turned off */
-#ifndef LWIP_DONT_PROVIDE_BYTEORDER_FUNCTIONS
-#define htons(x) lwip_htons(x)
-#define ntohs(x) lwip_ntohs(x)
-#define htonl(x) lwip_htonl(x)
-#define ntohl(x) lwip_ntohl(x)
-#endif
-
 /* These macros should be calculated by the preprocessor and are used
    with compile-time constants only (so that there is no little-endian
    overhead at runtime). */
@@ -109,9 +101,16 @@ u32_t lwip_htonl(u32_t x);
                      (((x) & 0x00ff0000UL) >>  8) | \
                      (((x) & 0xff000000UL) >> 24))
 #define PP_NTOHL(x) PP_HTONL(x)
-
 #endif /* BYTE_ORDER == BIG_ENDIAN */
 
+/* Provide usual function names as macros for users, but this can be turned off */
+#ifndef LWIP_DONT_PROVIDE_BYTEORDER_FUNCTIONS
+#define htons(x) lwip_htons(x)
+#define ntohs(x) lwip_ntohs(x)
+#define htonl(x) lwip_htonl(x)
+#define ntohl(x) lwip_ntohl(x)
+#endif
+
 /* Functions that are not available as standard implementations.
  * In cc.h, you can #define these to implementations available on
  * your platform to save some code bytes if you use these functions
diff --git a/ext/lwip/src/include/lwip/dhcp.h b/ext/lwip/src/include/lwip/dhcp.h
index d090afb..9750491 100755
--- a/ext/lwip/src/include/lwip/dhcp.h
+++ b/ext/lwip/src/include/lwip/dhcp.h
@@ -108,7 +108,7 @@ struct dhcp
 
 void dhcp_set_struct(struct netif *netif, struct dhcp *dhcp);
 /** Remove a struct dhcp previously set to the netif using dhcp_set_struct() */
-#define dhcp_remove_struct(netif) do { (netif)->dhcp = NULL; } while(0)
+#define dhcp_remove_struct(netif) netif_set_client_data(netif, LWIP_NETIF_CLIENT_DATA_INDEX_DHCP, NULL)
 void dhcp_cleanup(struct netif *netif);
 err_t dhcp_start(struct netif *netif);
 err_t dhcp_renew(struct netif *netif);
diff --git a/ext/lwip/src/include/lwip/fuck_off.h b/ext/lwip/src/include/lwip/fuck_off.h
index 5619491..2d326cb 100755
--- a/ext/lwip/src/include/lwip/fuck_off.h
+++ b/ext/lwip/src/include/lwip/fuck_off.h
@@ -43,8 +43,6 @@
 extern "C" {
 #endif
 
-#define LWIP_PROVIDE_ERRNO 0
-
 #ifdef LWIP_PROVIDE_ERRNO
 
 #define  EPERM            1  /* Operation not permitted */
@@ -176,13 +174,12 @@ extern "C" {
 #define  EMEDIUMTYPE    124  /* Wrong medium type */
 
 #ifndef errno
-//extern int errno;
+extern int errno;
 #endif
 
 #else /* LWIP_PROVIDE_ERRNO */
 
 /* Define LWIP_ERRNO_INCLUDE to <errno.h> to include the error defines here */
-#define LWIP_ERRNO_INCLUDE <errno.h>
 #ifdef LWIP_ERRNO_INCLUDE
 #include LWIP_ERRNO_INCLUDE
 #endif /* LWIP_ERRNO_INCLUDE */
diff --git a/ext/lwip/src/include/lwip/init.h b/ext/lwip/src/include/lwip/init.h
index a38845a..721bb57 100755
--- a/ext/lwip/src/include/lwip/init.h
+++ b/ext/lwip/src/include/lwip/init.h
@@ -54,7 +54,7 @@ extern "C" {
 /** x.X.x: Minor version of the stack */
 #define LWIP_VERSION_MINOR      0
 /** x.x.X: Revision of the stack */
-#define LWIP_VERSION_REVISION   2
+#define LWIP_VERSION_REVISION   3
 /** For release candidates, this is set to 1..254
   * For official releases, this is set to 255 (LWIP_RC_RELEASE)
   * For development versions (Git), this is set to 0 (LWIP_RC_DEVELOPMENT) */
diff --git a/ext/lwip/src/include/lwip/memp.h b/ext/lwip/src/include/lwip/memp.h
index 34134cb..c45aca8 100755
--- a/ext/lwip/src/include/lwip/memp.h
+++ b/ext/lwip/src/include/lwip/memp.h
@@ -38,6 +38,8 @@
 #ifndef LWIP_HDR_MEMP_H
 #define LWIP_HDR_MEMP_H
 
+#include "lwip/opt.h"
+
 #ifdef __cplusplus
 extern "C" {
 #endif
diff --git a/ext/lwip/src/include/lwip/stats.h b/ext/lwip/src/include/lwip/stats.h
index 685f57b..a0c818b 100755
--- a/ext/lwip/src/include/lwip/stats.h
+++ b/ext/lwip/src/include/lwip/stats.h
@@ -387,9 +387,9 @@ void stats_init(void);
 
 #if MEM_STATS
 #define MEM_STATS_AVAIL(x, y) lwip_stats.mem.x = y
-#define MEM_STATS_INC(x) STATS_INC(mem.x)
-#define MEM_STATS_INC_USED(x, y) STATS_INC_USED(mem, y)
-#define MEM_STATS_DEC_USED(x, y) lwip_stats.mem.x -= y
+#define MEM_STATS_INC(x) SYS_ARCH_INC(lwip_stats.mem.x, 1)
+#define MEM_STATS_INC_USED(x, y) SYS_ARCH_INC(lwip_stats.mem.x, y)
+#define MEM_STATS_DEC_USED(x, y) SYS_ARCH_DEC(lwip_stats.mem.x, y)
 #define MEM_STATS_DISPLAY() stats_display_mem(&lwip_stats.mem, "HEAP")
 #else
 #define MEM_STATS_AVAIL(x, y)
diff --git a/ext/lwip/test/unit/ip4/test_ip4.c b/ext/lwip/test/unit/ip4/test_ip4.c
new file mode 100755
index 0000000..383acf3
--- /dev/null
+++ b/ext/lwip/test/unit/ip4/test_ip4.c
@@ -0,0 +1,154 @@
+#include "test_ip4.h"
+
+#include "lwip/ip4.h"
+#include "lwip/inet_chksum.h"
+#include "lwip/stats.h"
+#include "lwip/prot/ip.h"
+#include "lwip/prot/ip4.h"
+
+#if !LWIP_IPV4 || !IP_REASSEMBLY || !MIB2_STATS || !IPFRAG_STATS
+#error "This tests needs LWIP_IPV4, IP_REASSEMBLY; MIB2- and IPFRAG-statistics enabled"
+#endif
+
+/* Helper functions */
+static void
+create_ip4_input_fragment(u16_t ip_id, u16_t start, u16_t len, int last)
+{
+  struct pbuf *p;
+  struct netif *input_netif = netif_list; /* just use any netif */
+  fail_unless((start & 7) == 0);
+  fail_unless(((len & 7) == 0) || last);
+  fail_unless(input_netif != NULL);
+
+  p = pbuf_alloc(PBUF_RAW, len + sizeof(struct ip_hdr), PBUF_RAM);
+  fail_unless(p != NULL);
+  if (p != NULL) {
+    err_t err;
+    struct ip_hdr *iphdr = (struct ip_hdr *)p->payload;
+    IPH_VHL_SET(iphdr, 4, sizeof(struct ip_hdr) / 4);
+    IPH_TOS_SET(iphdr, 0);
+    IPH_LEN_SET(iphdr, lwip_htons(p->tot_len));
+    IPH_ID_SET(iphdr, lwip_htons(ip_id));
+    if (last) {
+      IPH_OFFSET_SET(iphdr, lwip_htons(start / 8));
+    } else {
+      IPH_OFFSET_SET(iphdr, lwip_htons((start / 8) | IP_MF));
+    }
+    IPH_TTL_SET(iphdr, 5);
+    IPH_PROTO_SET(iphdr, IP_PROTO_UDP);
+    IPH_CHKSUM_SET(iphdr, 0);
+    ip4_addr_copy(iphdr->src, *netif_ip4_addr(input_netif));
+    iphdr->src.addr = lwip_htonl(lwip_htonl(iphdr->src.addr) + 1);
+    ip4_addr_copy(iphdr->dest, *netif_ip4_addr(input_netif));
+    IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, sizeof(struct ip_hdr)));
+
+    err = ip4_input(p, input_netif);
+    if (err != ERR_OK) {
+      pbuf_free(p);
+    }
+    fail_unless(err == ERR_OK);
+  }
+}
+
+/* Setups/teardown functions */
+
+static void
+ip4_setup(void)
+{
+}
+
+static void
+ip4_teardown(void)
+{
+  if (netif_list->loop_first != NULL) {
+    pbuf_free(netif_list->loop_first);
+    netif_list->loop_first = NULL;
+  }
+  netif_list->loop_last = NULL;
+}
+
+
+/* Test functions */
+
+START_TEST(test_ip4_reass)
+{
+  const u16_t ip_id = 128;
+  LWIP_UNUSED_ARG(_i);
+
+  memset(&lwip_stats.mib2, 0, sizeof(lwip_stats.mib2));
+
+  create_ip4_input_fragment(ip_id, 8*200, 200, 1);
+  fail_unless(lwip_stats.ip_frag.recv == 1);
+  fail_unless(lwip_stats.ip_frag.err == 0);
+  fail_unless(lwip_stats.ip_frag.memerr == 0);
+  fail_unless(lwip_stats.ip_frag.drop == 0);
+  fail_unless(lwip_stats.mib2.ipreasmoks == 0);
+
+  create_ip4_input_fragment(ip_id, 0*200, 200, 0);
+  fail_unless(lwip_stats.ip_frag.recv == 2);
+  fail_unless(lwip_stats.ip_frag.err == 0);
+  fail_unless(lwip_stats.ip_frag.memerr == 0);
+  fail_unless(lwip_stats.ip_frag.drop == 0);
+  fail_unless(lwip_stats.mib2.ipreasmoks == 0);
+
+  create_ip4_input_fragment(ip_id, 1*200, 200, 0);
+  fail_unless(lwip_stats.ip_frag.recv == 3);
+  fail_unless(lwip_stats.ip_frag.err == 0);
+  fail_unless(lwip_stats.ip_frag.memerr == 0);
+  fail_unless(lwip_stats.ip_frag.drop == 0);
+  fail_unless(lwip_stats.mib2.ipreasmoks == 0);
+
+  create_ip4_input_fragment(ip_id, 2*200, 200, 0);
+  fail_unless(lwip_stats.ip_frag.recv == 4);
+  fail_unless(lwip_stats.ip_frag.err == 0);
+  fail_unless(lwip_stats.ip_frag.memerr == 0);
+  fail_unless(lwip_stats.ip_frag.drop == 0);
+  fail_unless(lwip_stats.mib2.ipreasmoks == 0);
+
+  create_ip4_input_fragment(ip_id, 3*200, 200, 0);
+  fail_unless(lwip_stats.ip_frag.recv == 5);
+  fail_unless(lwip_stats.ip_frag.err == 0);
+  fail_unless(lwip_stats.ip_frag.memerr == 0);
+  fail_unless(lwip_stats.ip_frag.drop == 0);
+  fail_unless(lwip_stats.mib2.ipreasmoks == 0);
+
+  create_ip4_input_fragment(ip_id, 4*200, 200, 0);
+  fail_unless(lwip_stats.ip_frag.recv == 6);
+  fail_unless(lwip_stats.ip_frag.err == 0);
+  fail_unless(lwip_stats.ip_frag.memerr == 0);
+  fail_unless(lwip_stats.ip_frag.drop == 0);
+  fail_unless(lwip_stats.mib2.ipreasmoks == 0);
+
+  create_ip4_input_fragment(ip_id, 7*200, 200, 0);
+  fail_unless(lwip_stats.ip_frag.recv == 7);
+  fail_unless(lwip_stats.ip_frag.err == 0);
+  fail_unless(lwip_stats.ip_frag.memerr == 0);
+  fail_unless(lwip_stats.ip_frag.drop == 0);
+  fail_unless(lwip_stats.mib2.ipreasmoks == 0);
+
+  create_ip4_input_fragment(ip_id, 6*200, 200, 0);
+  fail_unless(lwip_stats.ip_frag.recv == 8);
+  fail_unless(lwip_stats.ip_frag.err == 0);
+  fail_unless(lwip_stats.ip_frag.memerr == 0);
+  fail_unless(lwip_stats.ip_frag.drop == 0);
+  fail_unless(lwip_stats.mib2.ipreasmoks == 0);
+
+  create_ip4_input_fragment(ip_id, 5*200, 200, 0);
+  fail_unless(lwip_stats.ip_frag.recv == 9);
+  fail_unless(lwip_stats.ip_frag.err == 0);
+  fail_unless(lwip_stats.ip_frag.memerr == 0);
+  fail_unless(lwip_stats.ip_frag.drop == 0);
+  fail_unless(lwip_stats.mib2.ipreasmoks == 1);
+}
+END_TEST
+
+
+/** Create the suite including all tests for this module */
+Suite *
+ip4_suite(void)
+{
+  testfunc tests[] = {
+    TESTFUNC(test_ip4_reass),
+  };
+  return create_suite("IPv4", tests, sizeof(tests)/sizeof(testfunc), ip4_setup, ip4_teardown);
+}
diff --git a/ext/lwip/test/unit/ip4/test_ip4.h b/ext/lwip/test/unit/ip4/test_ip4.h
new file mode 100755
index 0000000..71922b3
--- /dev/null
+++ b/ext/lwip/test/unit/ip4/test_ip4.h
@@ -0,0 +1,8 @@
+#ifndef LWIP_HDR_TEST_IP4_H
+#define LWIP_HDR_TEST_IP4_H
+
+#include "../lwip_check.h"
+
+Suite* ip4_suite(void);
+
+#endif
diff --git a/ext/lwip/test/unit/lwip_unittests.c b/ext/lwip/test/unit/lwip_unittests.c
index 84b895d..5563015 100755
--- a/ext/lwip/test/unit/lwip_unittests.c
+++ b/ext/lwip/test/unit/lwip_unittests.c
@@ -1,5 +1,6 @@
 #include "lwip_check.h"
 
+#include "ip4/test_ip4.h"
 #include "udp/test_udp.h"
 #include "tcp/test_tcp.h"
 #include "tcp/test_tcp_oos.h"
@@ -37,6 +38,7 @@ int main(void)
   SRunner *sr;
   size_t i;
   suite_getter_fn* suites[] = {
+    ip4_suite,
     udp_suite,
     tcp_suite,
     tcp_oos_suite,
diff --git a/ext/lwip/test/unit/lwipopts.h b/ext/lwip/test/unit/lwipopts.h
index a94c3fe..9bd672b 100755
--- a/ext/lwip/test/unit/lwipopts.h
+++ b/ext/lwip/test/unit/lwipopts.h
@@ -59,4 +59,7 @@
 /* Minimal changes to opt.h required for etharp unit tests: */
 #define ETHARP_SUPPORT_STATIC_ENTRIES   1
 
+/* MIB2 stats are required to check IPv4 reassembly results */
+#define MIB2_STATS                      1
+
 #endif /* LWIP_HDR_LWIPOPTS_H */