smbd opens some strange udp ports

I have found out that a strange udp port was opened in my system. That port is 1168. I know that 137 and 138 are needed for nmbd, but what is this port for? It comes out not from my base smbd daemon, but from a child process (I have mounted a filesystem there). Why is that? How can I firewall it? I do not think next time it will be the same port :-( Tazio