![]() |
![]() ![]() ![]() |
At the border, we drop:
|
At internal borders, we drop:
|
Of the NetBIOS packets dropped at the border, 99% are UDP/137. Holes are punched in the filter when specifically requested. |
In addition to providing an overview of our border policy, this slide points out an interesting thing about the IP implementation on (some?) Windows systems. When doing a reverse DNS lookup (IP address to name), these systems will first send an NetBIOS query to the IP address. This behavior suggests that the implementors were working under the assumption that the systems would be deployed on small, stable, local LANs.