diff --git a/app/include/lwip/app/espconn.h b/app/include/lwip/app/espconn.h
index e6e60fd1..6eda9e3a 100644
--- a/app/include/lwip/app/espconn.h
+++ b/app/include/lwip/app/espconn.h
@@ -394,5 +394,21 @@ extern sint8 espconn_igmp_join(ip_addr_t *host_ip, ip_addr_t *multicast_ip);
 *******************************************************************************/
 extern sint8 espconn_igmp_leave(ip_addr_t *host_ip, ip_addr_t *multicast_ip);
 
+/******************************************************************************
+ * FunctionName : espconn_recv_hold
+ * Description  : hold tcp receive
+ * Parameters   : espconn -- espconn to hold
+ * Returns      : none
+*******************************************************************************/
+extern sint8 espconn_recv_hold(struct espconn *pespconn);
+
+/******************************************************************************
+ * FunctionName : espconn_recv_unhold
+ * Description  : unhold tcp receive
+ * Parameters   : espconn -- espconn to unhold
+ * Returns      : none
+*******************************************************************************/
+extern sint8 espconn_recv_unhold(struct espconn *pespconn);
+
 #endif
 
diff --git a/app/include/lwip/tcp.h b/app/include/lwip/tcp.h
index 909ff9b7..7856a92d 100644
--- a/app/include/lwip/tcp.h
+++ b/app/include/lwip/tcp.h
@@ -277,6 +277,8 @@ struct tcp_pcb {
 
   /* KEEPALIVE counter */
   u8_t keep_cnt_sent;
+
+  u8_t hold;
 };
 
 struct tcp_pcb_listen {  
diff --git a/app/lwip/app/espconn.c b/app/lwip/app/espconn.c
index bd81e4d6..114f1b59 100644
--- a/app/lwip/app/espconn.c
+++ b/app/lwip/app/espconn.c
@@ -718,3 +718,32 @@ espconn_gethostbyname(struct espconn *pespconn, const char *hostname, ip_addr_t
     return dns_gethostbyname(hostname, addr, found, pespconn);
 }
 
+sint8 espconn_recv_hold(struct espconn *pespconn) {
+  espconn_msg *pnode = NULL;
+
+  if (pespconn == NULL) {
+    return ESPCONN_ARG;
+  }
+  pespconn->state = ESPCONN_WRITE;
+  if (!espconn_find_connection(pespconn, &pnode)) {
+      return ESPCONN_ARG;
+  }
+
+  espconn_tcp_hold(pnode);
+  return ESPCONN_OK;
+}
+
+sint8 espconn_recv_unhold(struct espconn *pespconn) {
+  espconn_msg *pnode = NULL;
+
+  if (pespconn == NULL) {
+    return ESPCONN_ARG;
+  }
+  pespconn->state = ESPCONN_WRITE;
+  if (!espconn_find_connection(pespconn, &pnode)) {
+      return ESPCONN_ARG;
+  }
+
+  espconn_tcp_unhold(pnode);
+  return ESPCONN_OK;
+}
diff --git a/app/lwip/app/espconn_tcp.c b/app/lwip/app/espconn_tcp.c
index 91843887..da5c441a 100644
--- a/app/lwip/app/espconn_tcp.c
+++ b/app/lwip/app/espconn_tcp.c
@@ -948,3 +948,19 @@ sint8 ICACHE_FLASH_ATTR espconn_tcp_delete(struct espconn *pdeletecon)
 			return ESPCONN_ARG;
 	}
 }
+
+void espconn_tcp_hold(void *arg) {
+    espconn_msg *ptcp_sent = arg;
+    struct tcp_pcb *pcb = NULL;
+    pcb = ptcp_sent->pcommon.pcb;
+
+    pcb->hold = 1;
+}
+
+void espconn_tcp_unhold(void *arg) {
+    espconn_msg *ptcp_sent = arg;
+    struct tcp_pcb *pcb = NULL;
+    pcb = ptcp_sent->pcommon.pcb;
+
+    pcb->hold = 0;
+}
diff --git a/app/lwip/core/tcp.c b/app/lwip/core/tcp.c
index e3193cc7..fe0bb913 100644
--- a/app/lwip/core/tcp.c
+++ b/app/lwip/core/tcp.c
@@ -1259,6 +1259,7 @@ tcp_alloc(u8_t prio)
 #endif /* LWIP_TCP_KEEPALIVE */
 
     pcb->keep_cnt_sent = 0;									//���ķ��ʹ���
+    pcb->hold = 0;
   }
   return pcb;
 }
diff --git a/app/lwip/core/tcp_in.c b/app/lwip/core/tcp_in.c
index 2f4a1c42..2aca07d4 100644
--- a/app/lwip/core/tcp_in.c
+++ b/app/lwip/core/tcp_in.c
@@ -1137,7 +1137,7 @@ tcp_receive(struct tcp_pcb *pcb)
 
   /* If the incoming segment contains data, we must process it
      further. */
-  if (tcplen > 0) {
+  if ((tcplen > 0) && (!pcb->hold)) {
     /* This code basically does three things:
 
     +) If the incoming segment contains data that is the next
diff --git a/app/modules/mqtt.c b/app/modules/mqtt.c
index a37974ec..13b182bc 100644
--- a/app/modules/mqtt.c
+++ b/app/modules/mqtt.c
@@ -725,8 +725,15 @@ static int mqtt_socket_connect( lua_State* L )
   if(mud == NULL)
     return 0;
 
-  if(mud->pesp_conn)
-    	c_free(mud->pesp_conn);
+  if(mud->pesp_conn){   //TODO: should I free tcp struct directly or ask user to call close()???
+    mud->pesp_conn->reverse = NULL;
+    if(mud->pesp_conn->proto.tcp)
+      c_free(mud->pesp_conn->proto.tcp);
+    mud->pesp_conn->proto.tcp = NULL;
+    c_free(mud->pesp_conn);
+    mud->pesp_conn = NULL;
+  }
+
   struct espconn *pesp_conn = NULL;
 	pesp_conn = mud->pesp_conn = (struct espconn *)c_zalloc(sizeof(struct espconn));
 	if(!pesp_conn)
diff --git a/app/modules/net.c b/app/modules/net.c
index 92514c9b..51639b54 100644
--- a/app/modules/net.c
+++ b/app/modules/net.c
@@ -665,6 +665,10 @@ static int net_start( lua_State* L, const char* mt )
   	return 0;
   }
 
+  if(nud->pesp_conn == NULL){
+    NODE_DBG("nud->pesp_conn is NULL.\n");
+    return 0;
+  }
   pesp_conn = nud->pesp_conn;
   port = luaL_checkinteger( L, stack );
   stack++;
@@ -1074,6 +1078,10 @@ static int net_dns( lua_State* L, const char* mt )
     return 0;
   }
 
+  if(nud->pesp_conn == NULL){
+    NODE_DBG("nud->pesp_conn is NULL.\n");
+    return 0;
+  }
   pesp_conn = nud->pesp_conn;
 
   if(!isserver || pesp_conn->type == ESPCONN_UDP){    // self_ref is only needed by socket userdata, or udp server
@@ -1185,6 +1193,54 @@ static int net_socket_send( lua_State* L )
   return net_send(L, mt);
 }
 
+static int net_socket_hold( lua_State* L )
+{
+  const char *mt = "net.socket";
+  struct espconn *pesp_conn = NULL;
+  lnet_userdata *nud;
+  size_t l;
+
+  nud = (lnet_userdata *)luaL_checkudata(L, 1, mt);
+  luaL_argcheck(L, nud, 1, "Server/Socket expected");
+  if(nud==NULL){
+    NODE_DBG("userdata is nil.\n");
+    return 0;
+  }
+
+  if(nud->pesp_conn == NULL){
+    NODE_DBG("nud->pesp_conn is NULL.\n");
+    return 0;
+  }
+  pesp_conn = nud->pesp_conn;
+  espconn_recv_hold(pesp_conn);
+
+  return 0;
+}
+
+static int net_socket_unhold( lua_State* L )
+{
+  const char *mt = "net.socket";
+  struct espconn *pesp_conn = NULL;
+  lnet_userdata *nud;
+  size_t l;
+
+  nud = (lnet_userdata *)luaL_checkudata(L, 1, mt);
+  luaL_argcheck(L, nud, 1, "Server/Socket expected");
+  if(nud==NULL){
+    NODE_DBG("userdata is nil.\n");
+    return 0;
+  }
+
+  if(nud->pesp_conn == NULL){
+    NODE_DBG("nud->pesp_conn is NULL.\n");
+    return 0;
+  }
+  pesp_conn = nud->pesp_conn;
+  espconn_recv_unhold(pesp_conn);
+
+  return 0;
+}
+
 // Lua: socket:dns( string, function(ip) )
 static int net_socket_dns( lua_State* L )
 {
@@ -1243,6 +1299,8 @@ static const LUA_REG_TYPE net_socket_map[] =
   { LSTRKEY( "close" ), LFUNCVAL ( net_socket_close ) },
   { LSTRKEY( "on" ), LFUNCVAL ( net_socket_on ) },
   { LSTRKEY( "send" ), LFUNCVAL ( net_socket_send ) },
+  { LSTRKEY( "hold" ), LFUNCVAL ( net_socket_hold ) },
+  { LSTRKEY( "unhold" ), LFUNCVAL ( net_socket_unhold ) },
   { LSTRKEY( "dns" ), LFUNCVAL ( net_socket_dns ) },
   // { LSTRKEY( "delete" ), LFUNCVAL ( net_socket_delete ) },
   { LSTRKEY( "__gc" ), LFUNCVAL ( net_socket_delete ) },