diff --git a/tap.go b/tap.go
index 6be7897..895b911 100644
--- a/tap.go
+++ b/tap.go
@@ -7,6 +7,7 @@ import (
 	"flag"
 	"fmt"
 	"log"
+	"net"
 	"os/exec"
 	gen "slimming/proto/gen"
 	"strings"
@@ -159,11 +160,17 @@ func (nc *NetCard) runRead() {
 				log.Fatal(err)
 			}
 
+			if rframe.Ethertype() != ethernet.IPv4 {
+				continue
+			}
+
+			log.Println(net.IP(rframe.Destination()).String())
+
 			var buffer *[][]byte
-			if buffer, ok = bytesMap[rframe.Destination().String()]; !ok {
+			if buffer, ok = bytesMap[net.IP(rframe.Destination()).String()]; !ok {
 				mbuffer := make([][]byte, 100)
 				buffer = &mbuffer
-				bytesMap[rframe.Destination().String()] = buffer
+				bytesMap[net.IP(rframe.Destination()).String()] = buffer
 			}
 
 			rframe = rframe[:n]