Problem: -------- When having a network with NT workstations/servers connected to the internet over a Brick, the Brick unreasonably establishes connections over ISDN to the internet without any user interaction. This behaviour is not a Brick's bug or problem, because the Brick simply connects to the internet when any PC from the LAN tries to reach an ip- adress outside the LAN. Especially Windows NT PCs are sending udp-packets at the broadcast- address of the LAN and therefore an internet connection will be established. The corresponding service is called Netbios over tcp/ip and it periodically transmits udp-packets at port 137 to search for other workstations and servers. Like described below, it's possible to suppress this behaviour, filtering the udp-broadcast-packets sent to the Brick. But there's still another NT service running over port 137, also udp, which has the purpose to synchronize the explorers content. If you display a remote networkdrives' (mounted over ISDN) content, the ISDN connection will remain established as long as the window is opened. You can't filter this too, you can't do anything but close the window! Example: -------- PC--------------LAN-----------Brick--------ISDN-----------Internet 192.168.168.100 192.168.168.1 Interface 'ISP' Netmask 255.255.255.0 1. Connect to Brick with telnet or serial connection and log in 2. enter 'setup' 3. choose IP->Access Lists 4. add a 'deny'-filter for interface 'en': BIANCA/BRICK-XM Setup Tool BinTec Communications GmbH [IP][ACCESS][EDIT]: Configure Access List Entry brick3 _______________________________________________________________________________ Mode deny Protocol udp Source Interface/Partner en Source Address Source Mask Source Port any Destination Address 192.168.168.255 Destination Mask 255.255.255.255 Destination Port specify Specify Port 137 SAVE CANCEL _______________________________________________________________________________ This filter will cause all broadcasts using udp-port 137 on the ethernet,
not to be transported over ISDN, eg using interface 'ISP'.
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