diff --git a/server_read_test.go b/server_read_test.go
index 060f322d..0f409a63 100644
--- a/server_read_test.go
+++ b/server_read_test.go
@@ -470,13 +470,6 @@ func TestServerRead(t *testing.T) {
 			require.NoError(t, err)
 			require.Equal(t, base.StatusOK, res.StatusCode)
 
-			// skip firewall opening
-			if transport == "udp" {
-				buf := make([]byte, 2048)
-				_, _, err := l2.ReadFrom(buf)
-				require.NoError(t, err)
-			}
-
 			// server -> client (direct)
 			switch transport {
 			case "udp":
@@ -504,6 +497,13 @@ func TestServerRead(t *testing.T) {
 				}
 			}
 
+			// skip firewall opening
+			if transport == "udp" {
+				buf := make([]byte, 2048)
+				_, _, err := l2.ReadFrom(buf)
+				require.NoError(t, err)
+			}
+
 			// server -> client (through stream)
 			if transport == "udp" || transport == "multicast" {
 				buf := make([]byte, 2048)
diff --git a/serversession.go b/serversession.go
index dd34815f..81e16b71 100644
--- a/serversession.go
+++ b/serversession.go
@@ -868,9 +868,7 @@ func (ss *ServerSession) handleRequest(sc *ServerConn, req *base.Request) (*base
 				sc.s.udpRTCPListener.addClient(ss.author.ip(), track.udpRTCPPort, ss, trackID, false)
 
 				// open the firewall by sending packets to the counterpart
-				byts, _ := (&rtcp.ReceiverReport{}).Marshal()
-				ss.s.udpRTCPListener.write(byts,
-					ss.setuppedTracks[trackID].udpRTCPAddr)
+				ss.WritePacketRTCP(trackID, &rtcp.ReceiverReport{})
 			}
 
 		case TransportUDPMulticast:
@@ -998,10 +996,8 @@ func (ss *ServerSession) handleRequest(sc *ServerConn, req *base.Request) (*base
 				ss.s.udpRTCPListener.addClient(ss.author.ip(), track.udpRTCPPort, ss, trackID, true)
 
 				// open the firewall by sending packets to the counterpart
-				byts, _ := (&rtp.Packet{Header: rtp.Header{Version: 2}}).Marshal()
-				ss.s.udpRTPListener.write(byts, ss.setuppedTracks[trackID].udpRTPAddr)
-				byts, _ = (&rtcp.ReceiverReport{}).Marshal()
-				ss.s.udpRTCPListener.write(byts, ss.setuppedTracks[trackID].udpRTCPAddr)
+				ss.WritePacketRTP(trackID, &rtp.Packet{Header: rtp.Header{Version: 2}})
+				ss.WritePacketRTCP(trackID, &rtcp.ReceiverReport{})
 			}
 
 		default: // TCP