routing problem

[Alaor Barroso de Carvalho Neto]

Hi, I have some troubles building my internet gateway to my network. I
already have a gateway machine running under linux, with two interfaces eth0
(192.168.1.1) and eth1 (external world), but I installed a new server
running FreeBSD6.2 with ipfilter and squid, in the test time with had the ip
192.168.1.240 in the rl0 and a external ip on rl1, I've configured some
machines in the network (3) to use it as gateway to test it and the
transparent proxy, everything worked fine. So I turned off my linux machine
and configured the BSD ip on rl0 to 192.168.1.1 and then it stop resolving
names. I have a DNS server in my network with the ip 192.168.1.2, I still
can ping to it and to the external world, but the names aren't resolved
anymore, it work for some seconds and then stop. When I turn on the
linuxmachine and plug it on the network with the ip 192.168.1.1 and change
the bsd ip to anything else it work again, resolve names and everything stay
just as suposed to be. If I turn off linux and set the rl0 to 192.168.1.1 it
stop resolving names but can ping to anywhere. Help!!!
in the rc.conf
gateway_enable="YES"
defaultrouter="X.X.X.X"
etc...
Everything seems to be OK.
Thankz for the attention
Hugs!
Alaor Neto