$OpenBSD$
--- net/net-ip.cpp.orig	Tue Jul 19 14:08:49 2011
+++ net/net-ip.cpp	Fri Aug 19 11:11:59 2011
@@ -232,6 +232,7 @@ int IPNetwork::command(int argc, const char*const* arg
 int IPNetwork::open(const char * host, int port, int ttl)
 {
 	char *g_addr;
+	Tcl& tcl = Tcl::instance();
 	// Check for SSM src address: Src,Group
 	if ((g_addr=(char*)strchr(host,(int)','))!=NULL) {
 		char s_addr_ssm[MAXHOSTNAMELEN];
@@ -273,6 +274,18 @@ int IPNetwork::open(const char * host, int port, int t
                 (IPAddress&)local_ = local.sin_addr;
 
 	disconnect_sock(ssock_);
+	/* 
+	 * Check whether a local port to be used was specified on the commandline
+	 * If so, make sure that when setting RTP port, it is even, and RTCP uneven
+	 */
+	if (tcl.attr("localport") != NULL) {
+		int localport;
+		localport = atoi(tcl.attr("localport"));	
+		if (ntohs(port) % 2 == 0)
+			port = (localport % 2 == 0) ? htons(localport) : htons(localport-1);
+		else
+			port = (localport % 2 == 0) ? htons(localport+1) : htons(localport);
+	}
 	rsock_ = openrsock(g_addr_, s_addr_ssm_, port, local_);
 	if (rsock_ < 0) {
 		rsock_ = ssock_;