Edubuntu routing question -- from external to internal (fwd)

[Gavin McCullagh]

Hi,

On Tue, 20 Nov 2007, Tom Wolfe wrote:

> I'm trying to allow access from the eth1 subnet (external) to the eth0
> subnet (ineternal/Thin Client)
> 
> I have a route set up on the external network
> (192.168.192.0/255.255.252.0) as follows:
> 
> route add -net 192.168.100.0 netmask 255.255.255.0 gw 192.168.192.18

So this route is installed on each machine in the external network.  That
sounds fine.

> The Edubuntu/Gutsy server is 192.168.192.18 on eth1 as you might gather.
> 
> pinging 192.168.100.254 (the Edubuntu server on eth0) from the 192.168.192.0 
> subnet gets no reply

You need to tell the edubuntu that it should forward packets between
networks (ie act as a router) or it will just ignore them.  This is
generally done using 

	echo 1 > /proc/sys/net/ipv4/ip_forward

which you should try first.

However, you're asking it to route packets between two private network
ranges which linux may not be keen on (as it breaks some network rules).
One usually uses an iptables NAT rule in this instance but you may be able
to get away without it, I'm not certain off the top of my head.

Gavin