[plug] Route (again)

[Jonathon Bates]

> > World		      Linux Router	  LAN
> > www ip network <------>eth0-eth1<-------->203.1.2.3 /24 subnet.
> >
> > What is hte easiest way to get the world to connect to the LAN?
> 
> Assuming the routes are set up so the Linux Router can see the LAN, and
> can also see the world, I would check the following:
> 
> 1. Is the 203.x.y.0/24 subnet definately routed to your Linux Router by
>    your ISP?
>    Run traceroutes from external sites (eg Spark, or
>    http://www.telstra.net/cgi-bin/trace) to check the packets are
>    definately getting through to your Linux Router.

Positive! :) 
After tracing to an IP within the LAN, it stops at the router and then
goes back and forth between the previous hops.
 
> 2. Ensure ip forwarding is on
>      "cat /proc/sys/net/ipv4/ip_forward" should give you a "1"

If I may ask, what exactly does this do? I thought it was only used
for masq'd hosts (I have tried doing this to no avail).

> 3. Make sure the computers on your LAN are using the Linux Router
>    as their default gateway.

Yeah they definately are! :)

> 4. Make sure your firewall is not interfering.  If in doubt, temporarily
>    flush your firewall rules completely[0]
>      iptables -F
>      for CHAIN in INPUT FORWARD OUTPUT
>      do
>        iptables -P $CHAIN ACCEPT
>      done

Checked that as well! 

> 5. If all else fails, tcpdump is your friend.
>    in 2 different terminals on the Linux Router run the commands:
>      tcpdump -lni eth0
>      tcpdump -lni eth1
>    then try accessing the world from your LAN & vice versa, and watch the
>    tcpdump windows to see what is actually happening to the packets.

I have tried this and from memory if i am trying to get in, no activity
occurs on the 203.1.2.3 subnet

> > The routes that have been set currently are the standard routes
> > that are created upon bootup of the machine.
> 
> Which are ... ?
> What is the output of  "route -n" ?