diff --git a/ext/ZeroTierOne b/ext/ZeroTierOne
index e01c0ad..21f4f16 160000
--- a/ext/ZeroTierOne
+++ b/ext/ZeroTierOne
@@ -1 +1 @@
-Subproject commit e01c0adff28602d48ad6f0d618bee072ec7843da
+Subproject commit 21f4f16e63f45577a614e25066e71080740fe175
diff --git a/ext/lwip.patch b/ext/lwip.patch
index a23956f..047f87f 100644
--- a/ext/lwip.patch
+++ b/ext/lwip.patch
@@ -11,6 +11,72 @@ index b7632489..786a294e 100644
  #include "lwip/opt.h"
  
  #if LWIP_SOCKET /* don't build if not configured for use in lwipopts.h */
+diff --git a/src/api/tcpip.c b/src/api/tcpip.c
+index 07b2f984..f10136e2 100644
+--- a/src/api/tcpip.c
++++ b/src/api/tcpip.c
+@@ -150,6 +150,11 @@ tcpip_thread(void *arg)
+       msg->msg.cb.function(msg->msg.cb.ctx);
+       break;
+ 
++    case TCPIP_MSG_SHUTDOWN:
++      LWIP_DEBUGF(TCPIP_DEBUG, ("tcpip_thread: SHUTDOWN %p\n", (void *)msg));
++      sys_sem_signal(msg->msg.api_call.sem);
++      return;
++
+     default:
+       LWIP_DEBUGF(TCPIP_DEBUG, ("tcpip_thread: invalid message: %d\n", msg->type));
+       LWIP_ASSERT("tcpip_thread: invalid message", 0);
+@@ -158,6 +163,49 @@ tcpip_thread(void *arg)
+   }
+ }
+ 
++err_t
++tcpip_shutdown(void)
++{
++  //struct tcpip_msg msg;
++  sys_sem_t sem;
++
++  /* If there is no tcpip mailbox, leave */
++  if (mbox == SYS_MBOX_NULL)
++      return ERR_OK;
++
++  /* Create semaphore for message */
++  sys_sem_new(&sem, 0);
++  LWIP_ASSERT("tcpip_terminate: failed to create semaphore\n",
++      sem != SYS_SEM_NULL);
++  if (sem == SYS_SEM_NULL) {
++    return ERR_MEM;
++  }
++
++  /* TODO: do we need to stop the timers? if so, how? */
++
++  struct tcpip_msg *msg;
++  LWIP_ASSERT("Invalid mbox", sys_mbox_valid_val(mbox));
++  msg = (struct tcpip_msg *)memp_malloc(MEMP_TCPIP_MSG_INPKT);
++
++  /* Tell tcpip thread to exit, and wait */
++  msg->msg.api_call.sem = &sem;
++  msg->type = TCPIP_MSG_SHUTDOWN;
++
++  if (sys_mbox_trypost(&mbox, msg) != ERR_OK) {
++    memp_free(MEMP_TCPIP_MSG_INPKT, msg);
++    return ERR_MEM;
++  }
++
++  sys_arch_sem_wait(&sem, 0);
++
++  /* clean up tcpip thread resources */
++
++  //sys_mbox_free(&mbox);
++  sys_sem_free(&sem);
++  mbox = SYS_MBOX_NULL;
++  return ERR_OK;
++}
++
+ /**
+  * Pass a received packet to tcpip_thread for input processing
+  *
 diff --git a/src/core/ipv6/ip6.c b/src/core/ipv6/ip6.c
 index f14e3342..facd3b21 100644
 --- a/src/core/ipv6/ip6.c
@@ -53,6 +119,30 @@ index 0b367181..2a5b77d4 100644
        return 1;
      }
    }
+diff --git a/src/core/timeouts.c b/src/core/timeouts.c
+index 8bf209a5..cf4e556a 100644
+--- a/src/core/timeouts.c
++++ b/src/core/timeouts.c
+@@ -186,6 +186,19 @@ void sys_timeouts_init(void)
+   timeouts_last_time = sys_now();
+ }
+ 
++/** Remove all timeouts */
++void sys_timeouts_free(void)
++{
++  size_t 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_untimeout(cyclic_timer, LWIP_CONST_CAST(void*, &lwip_cyclic_timers[i]));
++  }
++  /* Initialise timestamp for sys_check_timeouts */
++  timeouts_last_time = sys_now();
++}
++
+ /**
+  * Create a one-shot timer (aka timeout). Timeouts are processed in the
+  * following cases:
 diff --git a/src/include/lwip/errno.h b/src/include/lwip/errno.h
 index 641cffb0..cec43f7f 100644
 --- a/src/include/lwip/errno.h
@@ -89,3 +179,54 @@ index ee381aeb..b879f212 100644
  #define ip6_addr_cmp(addr1, addr2) (((addr1)->addr[0] == (addr2)->addr[0]) && \
                                      ((addr1)->addr[1] == (addr2)->addr[1]) && \
                                      ((addr1)->addr[2] == (addr2)->addr[2]) && \
+diff --git a/src/include/lwip/priv/tcpip_priv.h b/src/include/lwip/priv/tcpip_priv.h
+index 630efb14..41fb3e60 100644
+--- a/src/include/lwip/priv/tcpip_priv.h
++++ b/src/include/lwip/priv/tcpip_priv.h
+@@ -117,7 +117,8 @@ enum tcpip_msg_type {
+   TCPIP_MSG_UNTIMEOUT,
+ #endif /* LWIP_TCPIP_TIMEOUT && LWIP_TIMERS */
+   TCPIP_MSG_CALLBACK,
+-  TCPIP_MSG_CALLBACK_STATIC
++  TCPIP_MSG_CALLBACK_STATIC,
++  TCPIP_MSG_SHUTDOWN
+ };
+ 
+ struct tcpip_msg {
+diff --git a/src/include/lwip/sockets.h b/src/include/lwip/sockets.h
+index 2522056d..1af0c989 100644
+--- a/src/include/lwip/sockets.h
++++ b/src/include/lwip/sockets.h
+@@ -104,7 +104,7 @@ struct sockaddr_storage {
+ 
+ /* If your port already typedef's socklen_t, define SOCKLEN_T_DEFINED
+    to prevent this code from redefining it. */
+-#if !defined(socklen_t) && !defined(SOCKLEN_T_DEFINED)
++#if !defined(socklen_t) && !defined(SOCKLEN_T_DEFINED) && !defined(__ANDROID__)
+ typedef u32_t socklen_t;
+ #endif
+ 
+diff --git a/src/include/lwip/tcpip.h b/src/include/lwip/tcpip.h
+index f2f6b469..60d3578b 100644
+--- a/src/include/lwip/tcpip.h
++++ b/src/include/lwip/tcpip.h
+@@ -73,6 +73,7 @@ typedef void (*tcpip_callback_fn)(void *ctx);
+ struct tcpip_callback_msg;
+ 
+ void   tcpip_init(tcpip_init_done_fn tcpip_init_done, void *arg);
++err_t  tcpip_shutdown();
+ 
+ err_t  tcpip_inpkt(struct pbuf *p, struct netif *inp, netif_input_fn input_fn);
+ err_t  tcpip_input(struct pbuf *p, struct netif *inp);
+diff --git a/src/include/lwip/timeouts.h b/src/include/lwip/timeouts.h
+index c9b93aa0..74385dd4 100644
+--- a/src/include/lwip/timeouts.h
++++ b/src/include/lwip/timeouts.h
+@@ -94,6 +94,7 @@ struct sys_timeo {
+ };
+ 
+ void sys_timeouts_init(void);
++void sys_timeouts_free(void);
+ 
+ #if LWIP_DEBUG_TIMERNAMES
+ void sys_timeout_debug(u32_t msecs, sys_timeout_handler handler, void *arg, const char* handler_name);
diff --git a/include/lwipopts.h b/include/lwipopts.h
index 973421e..b2e5164 100644
--- a/include/lwipopts.h
+++ b/include/lwipopts.h
@@ -586,6 +586,11 @@ happening sooner than they should.
 -------------------------------- TCP Options -----------------------------------
 ------------------------------------------------------------------------------*/
 
+/**
+ * TCP_SYNMAXRTX: Maximum number of retransmissions of SYN segments.
+ */
+#define TCP_SYNMAXRTX                   12
+
 /**
  * LWIP_TCP==1: Turn on TCP.
  */
@@ -623,6 +628,22 @@ happening sooner than they should.
 
 #define LWIP_SOCKET                     1//(NO_SYS==0)
 
+/**
+ * LWIP_SO_SNDTIMEO==1: Enable send timeout for sockets/netconns and
+ * SO_SNDTIMEO processing.
+ */
+#define LWIP_SO_SNDTIMEO                1
+
+/**
+ * LWIP_SO_RCVTIMEO==1: Enable receive timeout for sockets/netconns and
+ * SO_RCVTIMEO processing.
+ */
+#define LWIP_SO_RCVTIMEO                1
+
+/**
+ * LWIP_SO_RCVBUF==1: Enable SO_RCVBUF processing.
+ */
+#define LWIP_SO_RCVBUF                  1
 
 /*------------------------------------------------------------------------------
 ------------------------------ Statistics Options ------------------------------