diff --git a/gtun/client.go b/gtun/client.go
index 1056949..8ee4e41 100644
--- a/gtun/client.go
+++ b/gtun/client.go
@@ -57,6 +57,12 @@ func NewClient(cfg *ClientConfig) *Client {
 }
 
 func (client *Client) Run() {
+	ifce, err := NewIfce()
+	if err != nil {
+		logs.Error("new interface fail: %v", err)
+		return
+	}
+
 	for {
 		server := client.serverAddr
 		conn, err := net.DialTimeout("tcp", server, time.Second*10)
@@ -78,13 +84,7 @@ func (client *Client) Run() {
 		client.myip = s2c.AccessIP
 		client.gw = s2c.Gateway
 		sndqueue := make(chan []byte)
-		ifce, err := NewIfce()
-		if err != nil {
-			logs.Error("new interface fail: %v", err)
-			return
-		}
-
-		err = setupIface(ifce, s2c.AccessIP, s2c.Gateway)
+		err = SetIfaceIP(ifce, s2c.AccessIP)
 		if err != nil {
 			logs.Error("setup iface fail: %v", err)
 			time.Sleep(time.Second * 3)
@@ -101,8 +101,7 @@ func (client *Client) Run() {
 		go rcv(conn, ifce, wg)
 		wg.Wait()
 
-		setdownIface(ifce, s2c.AccessIP, s2c.Gateway)
-		ifce.Close()
+		RemoveIfaceIP(ifce, s2c.AccessIP)
 		logs.Info("reconnecting")
 	}
 }
@@ -190,13 +189,15 @@ func snd(conn net.Conn, sndqueue chan []byte, done chan struct{}, wg *sync.WaitG
 
 func heartbeat(sndqueue chan []byte, done chan struct{}, wg *sync.WaitGroup) {
 	defer wg.Done()
+	tick := time.NewTicker(time.Second * 3)
+	defer tick.Stop()
 
 	for {
 		select {
 		case <-done:
 			return
 
-		case <-time.After(time.Second * 3):
+		case <-tick.C:
 			bytes, _ := common.Encode(common.C2S_HEARTBEAT, nil)
 			sndqueue <- bytes
 		}
diff --git a/gtun/ifce.go b/gtun/ifce.go
index 31ec353..0fc1d94 100644
--- a/gtun/ifce.go
+++ b/gtun/ifce.go
@@ -5,7 +5,6 @@ package gtun
 import (
 	"fmt"
 	"os/exec"
-	"runtime"
 	"strings"
 
 	"github.com/ICKelin/gtun/pkg/logs"
@@ -20,78 +19,30 @@ func NewIfce() (*water.Interface, error) {
 		return nil, err
 	}
 
-	return ifce, err
-}
+	output, err := exec.Command("ifconfig", []string{ifce.Name(), "up"}...).CombinedOutput()
+	if err != nil {
+		logs.Error("up inface %s fail: %s %v", ifce.Name(), string(output), err)
+		return nil, err
+	}
 
-type CMD struct {
-	cmd  string
-	args []string
+	return ifce, err
 }
 
-func setupIface(ifce *water.Interface, ip string, gw string) (err error) {
-	cmdlist := make([]*CMD, 0)
-
-	switch runtime.GOOS {
-	case "linux":
-		cmdlist = append(cmdlist, &CMD{cmd: "ifconfig", args: []string{ifce.Name(), "up"}})
-		args := strings.Split(fmt.Sprintf("addr add %s/24 dev %s", ip, ifce.Name()), " ")
-		cmdlist = append(cmdlist, &CMD{cmd: "ip", args: args})
-
-	case "darwin":
-		cmdlist = append(cmdlist, &CMD{cmd: "ifconfig", args: []string{ifce.Name(), "up"}})
-
-		args := strings.Split(fmt.Sprintf("%s %s %s", ifce.Name(), ip, ip), " ")
-		cmdlist = append(cmdlist, &CMD{cmd: "ifconfig", args: args})
-
-		args = strings.Split(fmt.Sprintf("add -net %s/24 %s", gw, ip), " ")
-		cmdlist = append(cmdlist, &CMD{cmd: "route", args: args})
-
-	case "windows":
-		logs.Error("do not support %s", runtime.GOOS)
-
-	}
-
-	logs.Info("set up interface")
-	for _, c := range cmdlist {
-		logs.Info("%s %s", c.cmd, c.args)
-		output, err := exec.Command(c.cmd, c.args...).CombinedOutput()
-		if err != nil {
-			return fmt.Errorf("run %s error %s", c, string(output))
-		}
+func SetIfaceIP(ifce *water.Interface, ip string) error {
+	args := strings.Split(fmt.Sprintf("addr add %s/24 dev %s", ip, ifce.Name()), " ")
+	output, err := exec.Command("ip", args...).CombinedOutput()
+	if err != nil {
+		return fmt.Errorf("set ip fail: %s %v", string(output), err)
 	}
 
 	return nil
 }
 
-func setdownIface(ifce *water.Interface, ip string, gw string) (err error) {
-	cmdlist := make([]*CMD, 0)
-
-	switch runtime.GOOS {
-	case "linux":
-		cmdlist = append(cmdlist, &CMD{cmd: "ifconfig", args: []string{ifce.Name(), "down"}})
-		args := strings.Split(fmt.Sprintf("addr del %s/24 dev %s", ip, ifce.Name()), " ")
-		cmdlist = append(cmdlist, &CMD{cmd: "ip", args: args})
-
-	case "darwin":
-		cmdlist = append(cmdlist, &CMD{cmd: "ifconfig", args: []string{ifce.Name(), "down"}})
-
-		args := strings.Split(fmt.Sprintf("%s %s %s", ifce.Name(), ip, ip), " ")
-		cmdlist = append(cmdlist, &CMD{cmd: "ifconfig", args: args})
-
-		args = strings.Split(fmt.Sprintf("del -net %s/24 %s", gw, ip), " ")
-		cmdlist = append(cmdlist, &CMD{cmd: "route", args: args})
-
-	case "windows":
-		logs.Error("do not support %s", runtime.GOOS)
-	}
-
-	logs.Info("set down interface")
-	for _, c := range cmdlist {
-		logs.Info("%s %s", c.cmd, c.args)
-		output, err := exec.Command(c.cmd, c.args...).CombinedOutput()
-		if err != nil {
-			return fmt.Errorf("run %s error %s", c, string(output))
-		}
+func RemoveIfaceIP(ifce *water.Interface, ip string) (err error) {
+	args := strings.Split(fmt.Sprintf("addr del %s/24 dev %s", ip, ifce.Name()), " ")
+	output, err := exec.Command("ip", args...).CombinedOutput()
+	if err != nil {
+		return fmt.Errorf("remove ip fail: %s %v", string(output), err)
 	}
 
 	return nil
diff --git a/gtund/forward.go b/gtund/forward.go
index 595cb63..5714f27 100644
--- a/gtund/forward.go
+++ b/gtund/forward.go
@@ -57,7 +57,10 @@ func (forward *Forward) Peer(dst string, buff []byte) error {
 		return err
 	}
 
-	sndbuf <- bytes
+	select {
+	case sndbuf <- bytes:
+	default:
+	}
 	logs.Debug("send dst %s bytes size: %d", dst, len(bytes))
 	return nil
 }
diff --git a/gtund/server.go b/gtund/server.go
index 5690c95..2014b48 100644
--- a/gtund/server.go
+++ b/gtund/server.go
@@ -55,7 +55,6 @@ func NewServer(cfg ServerConfig, dhcp *DHCP, iface *Interface) (*Server, error)
 
 func (s *Server) Run() error {
 	go s.readIface()
-	// go s.snd()
 
 	listener, err := net.Listen("tcp", s.listenAddr)
 	if err != nil {
@@ -117,7 +116,7 @@ func (s *Server) onConn(conn net.Conn) {
 	s2c.Nameservers = s.nameservers
 	s.authResp(conn, s2c)
 
-	sndbuf := make(chan []byte)
+	sndbuf := make(chan []byte, 10)
 	s.forward.Add(s2c.AccessIP, sndbuf)
 	defer s.forward.Del(s2c.AccessIP)