ICMP Forward
Not exactly a Debian-related question, but nonetheless:
We've got a home LAN with what used to be a debian-based
firewall/masquerade server, however we recently borrowed an ISDN router
while we sorted out some issues with the previous ISDN modem. The
firewall machine (192.168.0.1) is still set as the gateway for all the
home machines, with its gateway set to be the router (192.168.0.2). I've
noticed that rather than the router taking the whole packet and
forwarding it to the router, it seems to send ICMP redirect messages to
the originating machines telling them to use 192.168.0.2. Looking at the
frequency of these messages (around 5/sec) I'm assuming that these get
sent every time a new connection is attempted to be made.
However, I've noticed that the W2K boxes we've got change their routing
tables to have 192.168.0.2 as their gateway. Does anyone know
a) is this usual behaviour for any TCP/IP stack?
b) do the machines ignore the "real" (192.168.0.1) gateway when they
make a new connection?
c) if so, can I stop this behaviour?
(the reason for this is that we don't want the line to come up during
the day as we have to pay for this, and use the gateway machine to
control access to the router via cron manipulating the routing tables)
Cheers,
Gareth
--
Gareth Bowker | tgb96@aber.ac.uk
PhD Research Student | http://users.aber.ac.uk/tgb96/
Space Robotics Team | Office: (01970) 621528
University of Wales, Aberystwyth | Mobile: (07971) 219986
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