Re: packet forwarding.

[Mike Bird <mgb-debian@yosemite.net>]

On Sat August 2 2008 18:31:40 peasthope@shaw.ca wrote:
> My network is illustrated here now.
> http://carnot.pathology.ubc.ca/Network.jpg
>
> Forwarding is always on.
> dalton:~# cat /proc/sys/net/ipv4/ip_forward
> 1

<snip>

> Even without such a command this is the routing
> table on Dalton.

<snipped routing table, which does indeed show ...>

> According to the first line, Dalton knows
> that the route to joule.petershouse.invalid
> is through the tun0 interface.

<snip>

> So Cantor should be get a POP3 connection to
> joule.petershouse.invalid?  It gets only
> "no connection".

That routing table shows that dalton knows the route to joule.
From the network diagram we see that dalton also knows the
(connected) route to cantor via eth3 (aka eth1).  Assuming no
iptables blocks on any of the three systems, you still need to
ensure:

1) That cantor knows the route to joule (via dalton)
2) That joule knows the route to cantor (via dalton)

In short, every step along the way needs to know how to route
packets in both directions.

--Mike Bird