[Techtalk] no gateway, yet it works!

[Maria Blackmore]

On Wed, 11 Sep 2002, Carla Schroder wrote:

> OK, here's a fun lil mystery. Nowhere can I find a gateway setting on
> my home network- I have a little Linksys NAT firewall box. The gateway
> is 192.168.1.1, how original, but none of the client PCs have a
> gateway assigned to them. I've looked in every config file I can find:
> -redhat-config-network, the GUI configurator -/etc/sysconfig/network-
> empty

I like mysteries :)

> ifconfig shows no gateway. so why does it work? I have Internet and DHCP and 
> everything, how in de hell do the client PCs find the Linksys box???

gateways don't show up in ifconfig :)

you can look at your current routing table with the route command, I would
recommend using "route -n" so that it won't try to resolve the IP
addresses.  You're looking for the route with the destination and mask set
to "0.0.0.0" .. ie everywhere :)

if it doesn't have an entry for that then the answer is still quite
simple, you're probably using proxy arp.  Whereby a router will give an 
ARP response pointing to itself for any IP address not on the local
network, this means that all packets for the outside world get sent to it
anyway.  This can cause a lot of problems on a large network because you
end up with ARP tables filling up and things crashing because of that.

have fun :)

Maria