Operation Manual

Introduction to NetWare MultiProtocol Router for ISDN 3.1 27
Besides their toll saving function, most of the filters are also used for
security purposes, i.e. to prevent access from remote sites to servers
or services. The NetWare MultiProtocol Router for ISDN implements
filters and spoofings on the ISDN level as well as on the network
level. The ISDN-specific toll-saving filters and spoofings are listed
below:
- Watchdog Spoofing
- SPX Spoofing
- NCP Spoofing
- NW4/NDS Spoofing
- WAN LSP Hello Spoofing
- ARP Spoofing (only for IP remote nodes; always enabled)
- NetWare serialization packets filter
- NetBIOS (IPX packet type 20) broadcast filtering
- IPX Message Waiting Filter
- SNMP Over IPX filter
- SNMP Over IP filter
- NW4/NDS Filter
- Timesync Filter
- IPX Broadcast Filter (only for IPX remote nodes)
- IP Broadcast Filter (only for IP remote nodes)
Please note that filters, such as the Packet Forwarding Filter
(FILTCFG.NLM) and several configurable timers that are very
important to save tolls, such as the RIP/SAP Periodic Update Time-
out or the NLSP Hello Timeout, are provided on the network level.
You should check all filters, spoofings, and timers provided on the
network level in any case when configuring your router. Further
especially check the filters, when you use static routes instead of a
routing protocol to a remote site and you use the Disconnect Time-
out for this connection, since all ISDN specific filters and spoofings
are negotiated during an initial set-up of a B channel and are only
activated after a B channel has been set up. They are deactivated
when the B channel is logically cleared down by the Disconnect
Timeout. After that, any packet not filtered on the network level will
Introduc.pm6 27.05.97, 21:0327