diff --git a/.listener.go.kate-swp b/.listener.go.kate-swp
new file mode 100644
index 0000000..f82d04e
Binary files /dev/null and b/.listener.go.kate-swp differ
diff --git a/utils.go b/utils.go
index 3ce2133..b7f064c 100644
--- a/utils.go
+++ b/utils.go
@@ -18,3 +18,13 @@ func generateRandomMAC() net.HardwareAddr {
 
 	return mac
 }
+
+// Check if IP address is all zero.
+func isZeroAddr(ip net.IP) bool {
+	for _, b := range ip {
+		if b != 0x0 {
+			return false
+		}
+	}
+	return true
+}