Since the introduction of MS Windows 2000, it is possible to run MS Windows networking
without the use of NetBIOS over TCP/IP. NetBIOS over TCP/IP uses UDP port 137 for NetBIOS
name resolution and uses TCP port 139 for NetBIOS session services. When NetBIOS over
TCP/IP is disabled on MS Windows 2000 and later clients, then only the TCP port 445 is
used, and the UDP port 137 and TCP port 139 are not.