diff --git a/a8/udplistener.cc b/a8/udplistener.cc
index cf9e9e3..0085593 100644
--- a/a8/udplistener.cc
+++ b/a8/udplistener.cc
@@ -16,6 +16,12 @@
 
 namespace a8
 {
+
+    long long UdpPacket::GetRemoteKey()
+    {
+        return 0;
+    }
+
     struct UdpListenerImpl
     {
         a8::UdpListener* master = nullptr;
diff --git a/a8/udplistener.h b/a8/udplistener.h
index 235779b..9330d24 100644
--- a/a8/udplistener.h
+++ b/a8/udplistener.h
@@ -12,6 +12,8 @@ namespace a8
         char* buf = nullptr;
         int buf_len = 0;
         sockaddr_in remote_addr;
+
+        long long GetRemoteKey();
     };
 
     struct UdpListenerImpl;