Based on the document found at: »support.microsoft.com/default.as ··· &SD=HSCH
It appears that port 138/udp is used to broadcast information on browse lists and elections from a Windows Master Browser to Windows workstations.
If you filter (block) this port over a LAN, your ability to browse other machines on the LAN may be limited.
This port can be filtered from leaving your LAN (going out to the Internet) with no problems.[text was edited by author 2003-04-17 19:47:24]