diff --git a/src/agent.c b/src/agent.c
index 1e43de8..543b32f 100644
--- a/src/agent.c
+++ b/src/agent.c
@@ -187,7 +187,7 @@ int agent_process_frame(char *str_data, int data_size) {
     log_error("empty packet");
     return 0;
   }
-  log_trace("process_frame %*s\n", data_size, str_data);
+  // log_trace("process_frame %*s\n", data_size, str_data);
   // simple command
   if (data_size == strlen("EXIT") && strcmp(str_data, "EXIT") == 0) {
     agent_restore_stdin();
diff --git a/src/agentcall.c b/src/agentcall.c
index 96a1539..d4daa64 100644
--- a/src/agentcall.c
+++ b/src/agentcall.c
@@ -35,7 +35,7 @@ typedef struct thread_arg_pass_t {
 
 static void agentcall_server_request(void *p) {
   int sd = (int)p;
-  set_vnet_socket_nodelay(sd);
+  vnet_setsocketdefaultopt(sd);
   char recv_buf[READ_CHUNK_SIZE];
   int n, nwrote;
   log_info("sd: %d", sd);
diff --git a/src/fileexchange.c b/src/fileexchange.c
index bb2a1fb..2d2bbd2 100644
--- a/src/fileexchange.c
+++ b/src/fileexchange.c
@@ -37,12 +37,12 @@ typedef struct path_exchange {
 
 static int file_receiver_request(void *p) {
   int sd = (int)p;
-  set_vnet_socket_nodelay(sd);
+  vnet_setsocketdefaultopt(sd);
   char recv_buf[READ_CHUNK_SIZE];
   int n, nwrote;
   log_info("sd: %d", sd);
   if (vnet_readstring(sd, recv_buf, READ_CHUNK_SIZE) == 0) {
-    close(sd);
+    lwip_close(sd);
     return 0;
   }
   char *target_file_path = recv_buf;
@@ -77,12 +77,12 @@ int file_receiver_start() {
 
 static int file_sender_request(void *p) {
   int sd = (int)p;
-  set_vnet_socket_nodelay(sd);
+  vnet_setsocketdefaultopt(sd);
   char recv_buf[READ_CHUNK_SIZE];
   int n, nwrote;
   log_info("sd: %d", sd);
   if (vnet_readstring(sd, recv_buf, READ_CHUNK_SIZE) == 0) {
-    close(sd);
+    lwip_close(sd);
     return 0;
   }
   char *target_file_path = recv_buf;
diff --git a/src/lwipopts.h b/src/lwipopts.h
index a6aef93..0b5854c 100644
--- a/src/lwipopts.h
+++ b/src/lwipopts.h
@@ -135,6 +135,7 @@ a lot of data that needs to be copied, this should be set high. */
 #define LWIP_TCP 1
 #define TCP_TTL 255
 
+#define LWIP_TCP_KEEPALIVE  1
 /* Controls if TCP should queue segments that arrive out of
    order. Define to 0 if your device is low on memory. */
 #define TCP_QUEUE_OOSEQ 1
diff --git a/src/pipe.c b/src/pipe.c
index bd97cec..9af0adb 100644
--- a/src/pipe.c
+++ b/src/pipe.c
@@ -136,7 +136,7 @@ int vnet_notify_to_libuv(char *buf, size_t size) {
   f->buf = memdup(buf, size);
   f->len = size;
   queue_put(q, f);
-  log_info("add queue");
+  // log_info("add queue");
   data_income_notify.data = 1;  // set dry
   int r = uv_async_send(&data_income_notify);
   return 0;
diff --git a/src/portforward.c b/src/portforward.c
index 7a0c9fe..467e4f8 100644
--- a/src/portforward.c
+++ b/src/portforward.c
@@ -37,6 +37,9 @@ struct lwip_sockaddr_in {
   char sin_zero[SIN_ZERO_LEN];
 };
 
+
+
+
 static int port_forward_static_service_port = 7000;
 
 typedef struct port_listen {
@@ -47,12 +50,12 @@ typedef struct port_listen {
 
 static void portforward_static_server_request(void *p) {
   int sd = (int)p;
-  set_vnet_socket_nodelay(sd);
+  vnet_setsocketdefaultopt(sd);
   char recv_buf[READ_CHUNK_SIZE];
   int n, nwrote;
   CHECK(sd >= 0, "sd: %d", sd);
   int readbytes = 0;
-
+  //TODO (jdz) readn
   do {
     n = lwip_read(sd, recv_buf + readbytes, 1);
     if (n <= 0) {
@@ -63,7 +66,7 @@ static void portforward_static_server_request(void *p) {
     readbytes += 1;
   } while (*(recv_buf + readbytes - 1) != '\0');
   char *host = strdup(recv_buf);
-  log_info("target %s", host);
+
   readbytes = 0;
   do {
     n = lwip_read(sd, recv_buf + readbytes, sizeof(uint16_t));
@@ -76,9 +79,7 @@ static void portforward_static_server_request(void *p) {
   uint16_t port = ntohs(*((uint16_t *)(recv_buf)));
 
   log_info("target %s %hu", host, port);
-  // TODO(jdz) real connect the ip port or listen ip port
-  // -L -R 30 80
-  // connect first
+
   int sock;
   if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
     lwip_close(sd);
@@ -89,31 +90,29 @@ static void portforward_static_server_request(void *p) {
   struct addrinfo *res;
   snprintf(portaddr, sizeof(portaddr), "%d", port);
 
-
-  struct hostent *shes = gethostbyname(host);
-  if (!shes) {
+  char* ip = safe_gethostbyname(host, port);
+  if (ip == NULL) {
     close(sock);
     lwip_close(sd);
     return;
   }
-  free(host);
-  // TODO(jdz) thread safe
-  host = inet_ntoa(*(struct in_addr*)shes->h_addr);
-  log_info("use ip %s:%hu for domain", host, port);
-  struct sockaddr_in addr;
 
+  log_info("use ip %s:%hu for domain", ip, port);
+  struct sockaddr_in addr;
   memset(&addr, 0, sizeof(addr));
 #ifdef __APPLE__
   addr.sin_len = sizeof(addr);
 #endif
   addr.sin_family = AF_INET;
   addr.sin_port = htons(port);
-  addr.sin_addr.s_addr = inet_addr(host);
-  /* connect */
-  log_info("start connect %s:%hu", host, port);
+  addr.sin_addr.s_addr = inet_addr(ip);
+
+  log_info("start connect %s:%hu", ip, port);
+  free(ip);
   int ret = connect(sock, (struct sockaddr *)&addr, sizeof(addr));
   if (ret != 0) {
     lwip_close(sd);
+    close(sock);
     log_info("connect error return %d errno:%d %s", ret, errno,
              strerror(errno));
     return;
@@ -156,7 +155,7 @@ static void loop_lwipsocket_to_socket(int *arg) {
     }
     log_info("select ret %d", ret);
     if (!FD_ISSET(lwip_fd, &fdset)) {
-      // return;
+      // pass
     }
     int r = lwip_recv(lwip_fd, buf, READ_CHUNK_SIZE,
                       MSG_DONTWAIT);
@@ -171,11 +170,13 @@ static void loop_lwipsocket_to_socket(int *arg) {
     }
     log_info("write expect %d %d", fd, r);
     int writebytes = write(fd, buf, r);
-    log_info("writeed %d", writebytes);
+    log_info("written %d", writebytes);
     if (writebytes < 0) {
+      lwip_shutdown(lwip_fd, SHUT_RDWR);
       return;
     }
     if (writebytes == 0) {
+      lwip_shutdown(lwip_fd, SHUT_RDWR);
       return;
     }
   }
@@ -187,7 +188,31 @@ static void loop_socket_to_lwipsocket(int *arg) {
   int fd = arg[1];
   while (true) {
     char buf[READ_CHUNK_SIZE];
-    int r = read(fd, buf, READ_CHUNK_SIZE); //TODO
+
+    fd_set fdset;
+    FD_ZERO(&fdset);
+    FD_SET(fd, &fdset);
+    struct timeval tv;
+    tv.tv_usec = 500;
+    tv.tv_sec = 0;
+    int ret = select(fd + 1, &fdset, NULL, NULL, &tv);
+    if (ret < 0) {
+      if (errno == EINTR) continue;
+      if (errno == EBADF) {
+        log_fatal("fd: %d", fd);
+        return;  // TODO(jdz) fix
+      }
+      CHECK(ret > 0, "select ret:%d %s", ret, strerror(errno));
+    }
+    if (ret == 0) {
+      continue;
+    }
+    log_info("select ret %d", ret);
+    if (!FD_ISSET(fd, &fdset)) {
+      // pass
+    }
+    // TODO 这中间可能被close 导致read到 无效的fd
+    int r = read(fd, buf, READ_CHUNK_SIZE);  // TODO
     if (r < 0) {
       lwip_shutdown(lwip_fd, SHUT_RDWR);  // TODO(jdz) 最好去掉
       return;
@@ -199,9 +224,13 @@ static void loop_socket_to_lwipsocket(int *arg) {
 
     int writebytes = lwip_write(lwip_fd, buf, r);
     if (writebytes < 0) {
+      close(fd);
+      lwip_close(lwip_fd);
       return;
     }
     if (writebytes == 0) {
+      close(fd);
+      lwip_close(lwip_fd);
       return;
     }
     log_info("lwip_write %d %d", r, writebytes);
@@ -218,6 +247,8 @@ int pipe_lwip_socket_and_socket_pair(int lwip_fd, int fd) {
   pthread_create(&worker2, NULL, &loop_socket_to_lwipsocket, (void *)array);
   loop_lwipsocket_to_socket((void *)array);
   pthread_join(worker2, NULL);
+  log_info("lwip ip pair %d %d", lwip_fd, fd);
+  free(array);
   return 0;
 }
 
@@ -298,7 +329,7 @@ int portforward_static_start(char *src_host, uint16_t src_port, char *dst_host,
       comm_write_packet_to_cli(COMMAND_RETURN, strdup("bind local port error\n"),
                               sizeof("bind local port error\n"));
     }
-    return 0;
+    goto fail;
   }
   ret = listen(sock, 20);
   if (ret != 0) {
@@ -308,7 +339,7 @@ int portforward_static_start(char *src_host, uint16_t src_port, char *dst_host,
       comm_write_packet_to_cli(COMMAND_RETURN, strdup("listen error\n"),
                              sizeof("listen error\n"));
     }
-    return 0;
+    goto fail;
   }
 
   port_listen_t *pe = (port_listen_t *)malloc(sizeof(port_listen_t));
@@ -325,4 +356,8 @@ int portforward_static_start(char *src_host, uint16_t src_port, char *dst_host,
   sys_thread_new("portforward_static", portforward_service_handler, (void *)pe,
                  DEFAULT_THREAD_STACKSIZE, DEFAULT_THREAD_PRIO);
   return 0;
+
+  fail:
+  close(sock);
+  return 0;
 }
diff --git a/src/socksproxy.c b/src/socksproxy.c
index 662a94d..4cb68b2 100644
--- a/src/socksproxy.c
+++ b/src/socksproxy.c
@@ -25,7 +25,7 @@
 #include <sys/types.h>
 #include <time.h>
 #include <unistd.h>
-
+#include "utils.h"
 #include "log.h"
 #include "portforward.h"
 #include "vclient.h"
@@ -75,7 +75,8 @@ int readn(int fd, void *buf, int n) {
   return n;
 }
 
-static int writen(int fd, void *buf, int n) {
+
+static int lwip_writen(int fd, void *buf, int n) {
   int nwrite, left = n;
   while (left > 0) {
     if ((nwrite = lwip_write(fd, buf, left)) == -1) {
@@ -113,9 +114,12 @@ int readtocharR(int fd, char *buf, int bufsize) {
 }
 
 int report_error_to_client(int fd, char *message) {
+  if (message == NULL) {
+        message = "(null)";
+  }
   char buffer[512];
-  snprintf(buffer, sizeof(buffer), "HTTP/1.1 500 %s\r\n\r\n", message);
-  writen(fd, buffer, strlen(buffer));
+  snprintf(buffer, sizeof(buffer), "HTTP/1.1 500 Internal Server Error %s\r\n\r\n", message);
+  lwip_writen(fd, buffer, strlen(buffer));
 }
 
 int http_proxy(int fd, char *prefetch_data, int prefetch_data_size) {
@@ -158,7 +162,7 @@ int http_proxy(int fd, char *prefetch_data, int prefetch_data_size) {
   // printf("cmd:[%s]\n",cmd);
   if (strcmp(cmd, "GET") && strcmp(cmd, "POST") && strcmp(cmd, "CONNECT")) {
     report_error_to_client(fd, "This command is not supported");
-    close(fd);
+    lwip_close(fd);  // TODO (jdz) 遗留bug
     return 0;
   }
 
@@ -204,23 +208,25 @@ int http_proxy(int fd, char *prefetch_data, int prefetch_data_size) {
     log_info("socket error");
     return 0;
   }
-
-  struct hostent *shes = gethostbyname(host);
-  if (!shes) {
-    report_error_to_client(fd, hstrerror(h_errno));
-    close(fd);
+  char* ip = safe_gethostbyname(host, port);
+  if (ip == NULL) {
+    log_info("safe_gethostbyname empty ip");
+    report_error_to_client(fd, "empty ip");
+    lwip_close(fd);
+    close(rfd);
     return 0;
   }
   struct sockaddr_in sin;
   sin.sin_family = AF_INET;
-  bcopy(shes->h_addr, &sin.sin_addr, sizeof(struct in_addr));
+  sin.sin_addr.s_addr = inet_addr(ip);
+  free(ip);
   sin.sin_port = htons(port);
   if (connect(rfd, (struct sockaddr *)&sin, sizeof(struct sockaddr_in)) < 0) {
-    report_error_to_client(fd, strerror(buf2));
+    report_error_to_client(fd, strerror(errno));
     lwip_close(fd);
+    close(rfd);
     return 0;
   }
-
   if (strcmp(cmd, "CONNECT") != 0) {
     sprintf(buf2, "%s %s\n", cmd, url);
     if (write(rfd, buf2, strlen(buf2)) < 1) {
@@ -230,7 +236,7 @@ int http_proxy(int fd, char *prefetch_data, int prefetch_data_size) {
     }
   } else {
     char *reply = "HTTP/1.1 200 Connection Established\r\n\r\n";
-    if (writen(fd, reply, strlen(reply)) < 1) {
+    if (lwip_writen(fd, reply, strlen(reply)) < 1) {
       lwip_close(fd);
       close(rfd);
       return 0;
@@ -283,42 +289,27 @@ int app_connect(int type, void *buf, unsigned short int portnum) {
 
     return fd;
   } else if (type == DOMAIN) {
-    char portaddr[6];
-    struct addrinfo *res;
-    snprintf(portaddr, ARRAY_SIZE(portaddr), "%d", portnum);
-    log_info("getaddrinfo: %s %s", (char *)buf, portaddr);
-    int ret = getaddrinfo((char *)buf, portaddr, NULL, &res);
-    log_info("getaddrinfo done");
-    if (ret == EAI_NODATA) {
+
+    char* ip = safe_gethostbyname(buf, portnum);
+    if (ip == NULL) {
+      log_info("safe_gethostbyname empty ip");
+      close(fd);
       return -1;
-    } else if (ret == 0) {
-      struct addrinfo *r;
-      for (r = res; r != NULL; r = r->ai_next) {
-        fd = socket(r->ai_family, r->ai_socktype, r->ai_protocol);
-        if (fd == -1) {
-          continue;
-        }
-        log_info("connect host");
-        struct sockaddr_in *addr;
-        addr = (struct sockaddr_in *)r->ai_addr;
-        log_info("port %hu", ntohs(addr->sin_port));
-        log_info("inet_ntoa(in_addr)sin = %s\n",
-                 inet_ntoa((struct in_addr)addr->sin_addr));
-
-        ret = connect(fd, r->ai_addr, r->ai_addrlen);
-        if (ret == 0) {
-          log_info("connect host succ %d", fd);
-          freeaddrinfo(res);
-          return fd;
-        } else {
-          close(fd);
-        }
-      }
     }
-    freeaddrinfo(res);
-    return -1;
+    log_info("connect %s:%hu",ip, portnum);
+    memset(&remote, 0, sizeof(remote));
+    remote.sin_family = AF_INET;
+    remote.sin_addr.s_addr = inet_addr(ip);
+    free(ip);
+    remote.sin_port = htons(portnum);
+    fd = socket(AF_INET, SOCK_STREAM, 0);
+    if (connect(fd, (struct sockaddr *)&remote, sizeof(struct sockaddr_in)) < 0) {
+      log_info("connect() in app_connect");
+      close(fd);
+      return -1;
+    }
+    return fd;
   }
-
   return -1;
 }
 
@@ -358,7 +349,7 @@ char *socks5_auth_get_pass(int fd) {
 
 int socks5_auth_userpass(int fd) {
   char answer[2] = {VERSION5, USERPASS};
-  writen(fd, (void *)answer, ARRAY_SIZE(answer));
+  lwip_writen(fd, (void *)answer, ARRAY_SIZE(answer));
   char resp;
   readn(fd, (void *)&resp, sizeof(resp));
   log_info("auth %hhX", resp);
@@ -368,13 +359,13 @@ int socks5_auth_userpass(int fd) {
   if (strcmp(arg_username, username) == 0 &&
       strcmp(arg_password, password) == 0) {
     char answer[2] = {AUTH_VERSION, AUTH_OK};
-    writen(fd, (void *)answer, ARRAY_SIZE(answer));
+    lwip_writen(fd, (void *)answer, ARRAY_SIZE(answer));
     free(username);
     free(password);
     return 0;
   } else {
     char answer[2] = {AUTH_VERSION, AUTH_FAIL};
-    writen(fd, (void *)answer, ARRAY_SIZE(answer));
+    lwip_writen(fd, (void *)answer, ARRAY_SIZE(answer));
     free(username);
     free(password);
     return 1;
@@ -383,13 +374,13 @@ int socks5_auth_userpass(int fd) {
 
 int socks5_auth_noauth(int fd) {
   char answer[2] = {VERSION5, NOAUTH};
-  writen(fd, (void *)answer, ARRAY_SIZE(answer));
+  lwip_writen(fd, (void *)answer, ARRAY_SIZE(answer));
   return 0;
 }
 
 void socks5_auth_notsupported(int fd) {
   char answer[2] = {VERSION5, NOMETHOD};
-  writen(fd, (void *)answer, ARRAY_SIZE(answer));
+  lwip_writen(fd, (void *)answer, ARRAY_SIZE(answer));
 }
 
 void socks5_auth(int fd, int methods_count) {
@@ -447,9 +438,9 @@ char *socks_ip_read(int fd) {
 
 void socks5_ip_send_response(int fd, char *ip, unsigned short int port) {
   char response[4] = {VERSION5, OK, RESERVED, IP};
-  writen(fd, (void *)response, ARRAY_SIZE(response));
-  writen(fd, (void *)ip, IPSIZE);
-  writen(fd, (void *)&port, sizeof(port));
+  lwip_writen(fd, (void *)response, ARRAY_SIZE(response));
+  lwip_writen(fd, (void *)ip, IPSIZE);
+  lwip_writen(fd, (void *)&port, sizeof(port));
 }
 
 char *socks5_domain_read(int fd, unsigned char *size) {
@@ -472,32 +463,14 @@ void socks5_ip_send_response(int fd, char *ip, unsigned short int port)
         writen(fd, (void *)&port, sizeof(port));
 }
 */
-
 void socks5_domain_send_response(int fd, char *domain, unsigned char size,
-                                 uint16_t port) {
-  char response[4] = {VERSION5, OK, RESERVED, IP};
-  writen(fd, (void *)response, sizeof(response));
-#if 0
-	buf->data[0] = 0x5;
-	buf->data[1] = 0x0;
-	buf->data[2] = 0x0;
-	buf->data[3] = 0x1;
-	int s_addr = inet_aton("0.0.0.0", NULL);
-	uint32_t us_addr = htonl(s_addr);
-	memcpy(&buf->data[4], &us_addr, 4);
-	buf->data[4] = 0x1;
-	buf->data[4 + 4] = 0x19;
-	buf->data[4 + 5] = 0x19;
-	buf->used = 10;
-#endif
-  char buf[4];
-  int s_addr = inet_aton("0.0.0.0", NULL);
-  uint32_t us_addr = htonl(s_addr);
-  memcpy(buf, &us_addr, 4);
-  buf[0] = 0x1;
-  writen(fd, (void *)buf, sizeof(buf));
-  // writen(fd, (void *)domain, size * sizeof(char));
-  writen(fd, (void *)&port, sizeof(port));
+                                 unsigned short int port)
+{
+  char response[4] = { VERSION5, OK, RESERVED, DOMAIN };
+  lwip_writen(fd, (void *)response, ARRAY_SIZE(response));
+  lwip_writen(fd, (void *)&size, sizeof(size));
+  lwip_writen(fd, (void *)domain, size * sizeof(char));
+  lwip_writen(fd, (void *)&port, sizeof(port));
 }
 
 int socks4_is_4a(char *ip) {
@@ -529,12 +502,12 @@ int socks4_read_nstring(int fd, char *buf, int size) {
 
 void socks4_send_response(int fd, int status) {
   char resp[8] = {0x00, (char)status, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
-  writen(fd, (void *)resp, ARRAY_SIZE(resp));
+  lwip_writen(fd, (void *)resp, ARRAY_SIZE(resp));
 }
 
 void *app_thread_process(void *fd) {
   int net_fd = (int)fd;
-  set_vnet_socket_nodelay(net_fd);
+  vnet_setsocketdefaultopt(net_fd);
   int version = 0;
   int inet_fd = -1;
   char header[255];
diff --git a/src/utils.c b/src/utils.c
index 00789ad..3a190ce 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -9,7 +9,12 @@
 
 #define TERMTUNNEL_UTILS_H
 #include "utils.h"
-
+#include "log.h"
+#include <arpa/inet.h>
+#include <ctype.h>
+#include <errno.h>
+#include <netdb.h>
+#include <netinet/tcp.h>
 #include <fcntl.h>
 #include <stdbool.h>
 #include <stdio.h>
@@ -94,4 +99,33 @@ void set_stdin_raw() {
   _stdin_is_raw = true;
 }
 
+
+char* safe_gethostbyname(char *host, uint16_t port) {
+    log_info("gethostbyname %s:%hu", host, port);
+    char portaddr[6];
+    struct addrinfo *res;
+    snprintf(portaddr, sizeof(portaddr), "%d", port);
+    int ret = getaddrinfo((char *)host, portaddr, NULL, &res);
+    if (ret == EAI_NODATA) {
+      printf("gethostbyname EAI_NODATA");
+      return NULL;
+    } else if (ret == 0) {
+      struct addrinfo *r;
+      for (r = res; r != NULL; r = r->ai_next) {
+        // TODO(jdz) if == ipv4 
+        // int fd = socket(r->ai_family, r->ai_socktype, r->ai_protocol);
+        struct sockaddr_in *addr;
+        addr = (struct sockaddr_in *)r->ai_addr;
+        char *ret = malloc(INET_ADDRSTRLEN);
+        inet_ntop(AF_INET, &(addr->sin_addr), ret, INET_ADDRSTRLEN);
+        // inet_pton(AF_INET, "192.0.2.33", &(sa.sin_addr));
+        freeaddrinfo(res);
+        return ret;
+    }
+    freeaddrinfo(res);
+    }
+    return NULL;
+}
+
+
 #endif
\ No newline at end of file
diff --git a/src/utils.h b/src/utils.h
index e56bfec..bc6eb30 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -9,7 +9,7 @@
 
 #define TERMTUNNEL_UTILS_H
 #include <assert.h>
-
+#include <stdint.h>
 #include "log.h"
 #define CHECK(x, ...)       \
   if (!(x)) {               \
@@ -22,4 +22,5 @@ extern void set_stdin_raw();
 extern void restore_stdin();
 extern void *memdup(const void *src, size_t n);
 extern const char *green_encode(const char *buf, int len, int *result_len);
+extern char* safe_gethostbyname(char *buf, uint16_t port);
 #endif
\ No newline at end of file
diff --git a/src/vnet.c b/src/vnet.c
index 7d44cf9..e019d11 100644
--- a/src/vnet.c
+++ b/src/vnet.c
@@ -42,10 +42,12 @@ char *server_ip = "192.168.1.111";
 
 int16_t listen_port = 700;
 
-void set_vnet_socket_nodelay(int nfd) {
-  int flags = 1;
-  size_t flglen = sizeof(flags);
-  lwip_setsockopt(nfd, SOL_SOCKET, TCP_NODELAY, &flags, &flglen);
+void vnet_setsocketdefaultopt(int nfd) {
+  int flags;
+  flags = 1;
+  lwip_setsockopt(nfd, SOL_SOCKET, TCP_NODELAY, &flags, sizeof(flags));
+  flags = 1;
+  lwip_setsockopt(nfd, SOL_SOCKET, SO_KEEPALIVE, &flags, sizeof(flags));
 }
 
 
@@ -137,7 +139,7 @@ int vnet_tcp_connect(uint16_t port) {
   addr.sin_family = AF_INET;
   addr.sin_port = lwip_htons(port);
   addr.sin_addr.s_addr = inet_addr(server_ip);
-  set_vnet_socket_nodelay(s);
+  vnet_setsocketdefaultopt(s);
   /* connect */
   int ret = lwip_connect(s, (struct sockaddr *)&addr, sizeof(addr));
   if (ret == 0) {
diff --git a/src/vnet.h b/src/vnet.h
index 3a92b11..b76f628 100644
--- a/src/vnet.h
+++ b/src/vnet.h
@@ -18,7 +18,7 @@ int vnet_send(int s, const void *data, size_t size);
 int vnet_recv(int s, const void *data, size_t size);
 int vnet_listen_at(uint16_t port, void *cb,char* thread_desc);
 int vnet_close(int s);
-void set_vnet_socket_nodelay(int nfd);
+void vnet_setsocketdefaultopt(int nfd);
 int vnet_readn(int fd, void *buf, int n);
 int vnet_readstring(int fd, char *buf, int n);
 #endif