diff --git a/device.go b/device.go
index abb409f..f9f6707 100644
--- a/device.go
+++ b/device.go
@@ -11,6 +11,7 @@ import (
 	"os/exec"
 	gen "slimming/proto/gen"
 	"strings"
+	"sync"
 	"sync/atomic"
 	"time"
 
@@ -31,6 +32,14 @@ type NetCard struct {
 	server    *RPCServer
 
 	clientMap map[string]*RPCClient
+
+	lock sync.Mutex
+}
+
+func (nc *NetCard) Lock(do func()) {
+	nc.lock.Lock()
+	defer nc.lock.Unlock()
+	do()
 }
 
 type RPCClient struct {
@@ -176,11 +185,14 @@ func (nc *NetCard) runRead() {
 			var rframe ethernet.Frame
 			rframe.Resize(1500)
 
-			n, err := ifce.Read([]byte(rframe))
-			if err != nil {
-				log.Fatal(err)
-			}
-			rframe = rframe[:n]
+			nc.Lock(func() {
+				n, err := ifce.Read([]byte(rframe))
+				if err != nil {
+					log.Fatal(err)
+				}
+				rframe = rframe[:n]
+			})
+
 			if !waterutil.IsIPv4(rframe) || waterutil.IPv4Source(rframe).Equal(net.IPv4(0, 0, 0, 0)) {
 				continue
 			}
@@ -260,12 +272,15 @@ func (nc *NetCard) runWrite() {
 
 		log.Printf("get wframes decode len: %d", len(bufs[0]))
 
-		for _, buf := range bufs {
-			_, err := ifce.Write(buf)
-			if err != nil {
-				log.Panic(err)
+		nc.Lock(func() {
+			for _, buf := range bufs {
+				_, err := ifce.Write(buf)
+				if err != nil {
+					log.Panic(err)
+				}
 			}
-		}
+		})
+
 	}
 
 }