diff --git a/common.cpp b/common.cpp
index 8462336..58e9cc1 100644
--- a/common.cpp
+++ b/common.cpp
@@ -964,7 +964,7 @@ int new_listen_socket2(int &fd,address_t &addr)
 
 	return 0;
 }
-int new_connected_socket2(int &fd,address_t &addr,bool bind_enabled,address_t &bind_addr)
+int new_connected_socket2(int &fd,address_t &addr,bool bind_enabled,address_t &bind_addr,char interface_string[])
 {
 	fd = socket(addr.get_type(), SOCK_DGRAM, IPPROTO_UDP);
 	if (fd < 0) {
@@ -978,6 +978,14 @@ int new_connected_socket2(int &fd,address_t &addr,bool bind_enabled,address_t &b
 		myexit(1);
 	}
 
+	if (strlen(interface_string) > 0) {
+		if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, interface_string, strlen(interface_string)) < 0) {
+			mylog(log_fatal,"socket interface bind error\n");
+			//perror("socket bind error");
+			myexit(1);
+		}
+	}
+
 	setnonblocking(fd);
 	set_buf_size(fd, socket_buf_size);
 
diff --git a/common.h b/common.h
index 1772293..7c551b7 100644
--- a/common.h
+++ b/common.h
@@ -446,7 +446,7 @@ int new_listen_socket(int &fd,u32_t ip,int port);
 int new_connected_socket(int &fd,u32_t ip,int port);
 
 int new_listen_socket2(int &fd,address_t &addr);
-int new_connected_socket2(int &fd,address_t &addr,bool bind_enabled,address_t &bind_addr);
+int new_connected_socket2(int &fd,address_t &addr,bool bind_enabled,address_t &bind_addr,char interface_string[]);
 
 struct not_copy_able_t
 {
diff --git a/main.cpp b/main.cpp
index 7164058..1285de2 100644
--- a/main.cpp
+++ b/main.cpp
@@ -37,7 +37,8 @@ static void print_help()
 	printf("    --report              <number>        turn on send/recv report, and set a period for reporting, unit: s\n");
 
 	printf("advanced options:\n");
-	printf("    -b,--bind             ip:port         force all output packets to go through this ip. Set port to 0 to use a random one.\n");
+	printf("    -b,--bind             ip:port         force all output packets to go through this address. Set port to 0 to use a random one.\n");
+	printf("    --interface           <string>        force all output packets to go through this interface.\n");
 	printf("    --mode                <number>        fec-mode,available values: 0,1; mode 0(default) costs less bandwidth,no mtu problem.\n");
 	printf("                                          mode 1 usually introduces less latency, but you have to care about mtu.\n");
 	printf("    --mtu                 <number>        mtu. for mode 0, the program will split packet to segment smaller than mtu value.\n");
diff --git a/misc.cpp b/misc.cpp
index 5c25e0c..f60d8da 100644
--- a/misc.cpp
+++ b/misc.cpp
@@ -28,6 +28,8 @@ int output_interval_max=0*1000;
 
 int fix_latency=0;
 
+char interface_string[16];
+
 bool has_b=false;
 address_t local_addr,remote_addr,bind_addr;
 //u32_t local_ip_uint32,remote_ip_uint32=0;
@@ -649,6 +651,7 @@ void process_arg(int argc, char *argv[])
 		{"report", required_argument,    0, 1},
 		{"delay-capacity", required_argument,    0, 1},
 		{"mtu", required_argument,    0, 1},
+		{"interface", required_argument,    0, 1},
 		{"mode", required_argument,   0,1},
 		{"timeout", required_argument,   0,1},
 		{"decode-buf", required_argument,   0,1},
@@ -950,6 +953,16 @@ void process_arg(int argc, char *argv[])
 					myexit(-1);
 				}
 			}
+			else if(strcmp(long_options[option_index].name,"interface")==0)
+			{
+				sscanf(optarg,"%s\n",interface_string);
+				mylog(log_debug,"interface=%s\n",interface_string);
+				if(strlen(interface_string)==0)
+				{
+					mylog(log_fatal,"interface_string len=0??\n");
+					myexit(-1);
+				}
+			}
 			else if(strcmp(long_options[option_index].name,"timeout")==0)
 			{
 				sscanf(optarg,"%d",&g_fec_par.timeout);
diff --git a/misc.h b/misc.h
index f7cda35..1bfd495 100644
--- a/misc.h
+++ b/misc.h
@@ -39,6 +39,8 @@ extern int fix_latency;
 //extern char local_ip[100], remote_ip[100];
 //extern int local_port, remote_port;
 
+extern char interface_string[16];
+
 extern bool has_b;
 extern address_t local_addr,remote_addr,bind_addr;
 
diff --git a/tunnel_client.cpp b/tunnel_client.cpp
index a7458e0..93a4bde 100644
--- a/tunnel_client.cpp
+++ b/tunnel_client.cpp
@@ -295,7 +295,7 @@ int tunnel_client_event_loop()
     int & remote_fd=conn_info.remote_fd;
     fd64_t &remote_fd64=conn_info.remote_fd64;
 
-	assert(new_connected_socket2(remote_fd,remote_addr,has_b,bind_addr)==0);
+	assert(new_connected_socket2(remote_fd,remote_addr,has_b,bind_addr,interface_string)==0);
 	remote_fd64=fd_manager.create(remote_fd);
 
 	mylog(log_debug,"remote_fd64=%llu\n",remote_fd64);
diff --git a/tunnel_server.cpp b/tunnel_server.cpp
index 9285a87..97e674b 100644
--- a/tunnel_server.cpp
+++ b/tunnel_server.cpp
@@ -232,7 +232,7 @@ static void local_listen_cb(struct ev_loop *loop, struct ev_io *watcher, int rev
 			}
 
 			int new_udp_fd;
-			ret=new_connected_socket2(new_udp_fd,remote_addr,has_b,bind_addr);
+			ret=new_connected_socket2(new_udp_fd,remote_addr,has_b,bind_addr,interface_string);
 
 			if (ret != 0) {
 				mylog(log_warn, "[%s]new_connected_socket failed\n",addr.get_str());