Some questions on networking gateways

[Timothy Murphy]

I have a home LAN on network 192.168.2.0,
with a server at 192.168.2.2,
and various other laptops, iphones, etc on the LAN,
eg I am currently on laptop 192.168.2.7 .

There seem to be 3 places where gateways are specified:

1. In /etc/dhcpd.conf on the server, under "option routers";

2. In /etc/sysconfig/network-scripts/ifcfg-*
on the client machines;

3. In /etc/network on these machines.

I've read that the entries in ifcfg-* are ignored?

I haven't actually given gateways in /etc/network anywhere.
Perhaps I should?

My server has address 192.168.2.2 on eth1,
and address 192.168.1.2 on eth0, which is
connected to my ADSL modem with address 192.168.1.254 .

Now I'm wondering if I should give
GATEWAY=192.168.2.2 or GATEWAY=192.168.1.254
on client machines?

route -n on the server gives
------------------------------
Destination     Gateway         Genmask         Flags Metric Ref    Use 
Iface
192.168.5.2     0.0.0.0         255.255.255.255 UH    0      0        0 tun0
192.168.5.0     192.168.5.2     255.255.255.0   UG    0      0        0 tun0
192.168.2.0     0.0.0.0         255.255.255.0   U     0      0        0 eth1
192.168.1.0     0.0.0.0         255.255.255.0   U     0      0        0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U     0      0        0 eth1
0.0.0.0         192.168.1.254   0.0.0.0         UG    0      0        0 eth0
------------------------------
I'm not sure how it found the (correct) default gateway 192.168.1.254 ?

These questions arise because I tried changing my server
to machine 192.168.1.5, connected to the modem.
Everything worked fine on the new server,
but I could not access the ethernet on other machines,
even after modifying the route tables on these machines
to have default gateway 192.168.2.5 (the new server).

I tried both with NetworkManager and with the network service,
but neither worked satisfactorily.

Any enlightenment gratefully received.

-- 
Timothy Murphy  
e-mail: gayleard /at/ eircom.net
tel: +353-86-2336090, +353-1-2842366
s-mail: School of Mathematics, Trinity College, Dublin 2, Ireland