Wow. I got a headache trying to follow all of those routes. Truly
complicated stuff. Let's dig in!


>  Site 1:  10.10.1.0
>  eth0 10.10.1.40/24
>  eth1 192.168.1.254/24
>
>  Destination  Mask            Gateway        Dev
>  0.0.0.0      0.0.0.0         10.10.1.254    eth0  (to internet)
>  10.10.1.0    255.255.255.0   10.10.1.40     eth0  (wired interface)
>  10.10.12.0   255.255.255.0   192.168.1.253  eth1  (wireless to site 2)
>  10.10.13.0   255.255.255.0   192.168.1.253  eth1  (wireless to site 2)
>  192.168.1.0  255.255.255.0   192.168.1.254  eth1  (wireless interface)
>  192.168.2.0  255.255.255.0   192.168.1.253  eth1  (wireless to site 2)

As a side note here, you can do some trimming down of routes pretty
thoroughly. For example, the 10.10.12.x and 10.10.13.x can be condensed
into 10.10.12.0 255.255.254.0 with a gateway of 192.168.1.253. Remember,
the router only needs to know how to send to the next hop on the path;
the next hop's job is to determine what to do with it. This is the same
reasoning behind what Matt said regarding using a 0.0.0.0 gateway. With
the subnet your worried about, there should be some hop in there between
the site's individual router and that destination net that will examine
the destination traffic and send it correctly. Sending stuff straight out
the default gateway should work just fine as long as there's something
between you and the Internet that can catch the traffic and redirect it
(locally).

In the one I pointed out, Site 2 is going to be doing all the work to
determine where the IPs in those two /24s are going to be going. All Site
1 needs to know is how to get it to site two. If whatever has the
10.10.1.254 IP has routes for public IPs that are NOT destined for the
general internet (and any devices it sends to also have those routes)
shoving it out default gateway works.

Now, you stated that the problem seems to be coming from trying to reach
Site 3 from Site 1, yes?

Site 1 sends traffic from - for example - 10.10.1.8 to a host on Site 3 at
10.10.13.20. Assuming 10.10.1.40 is Default Gateway for all hosts on
10.10.1.0/24 except for the 254 host.

10.10.1.8 -> 10.10.1.40 -> 192.168.1.253 -> 10.10.12.253 -> 192.168.2.253
-> 10.10.13.20.

Response would be:

10.10.13.20 -> 10.10.13.254 -> 192.168.2.254 -> 10.10.12.254 ->
192.168.1.254 -> 10.10.1.8


Site 3 appears to be the problem, though without knowing for sure what the
firewalling is doing there I can't say that the firewalling or the routing
is actually the issue here. Check to make sure IP Forwarding is turned on
as was suggested, and if it is, try adding a specific route for
10.10.1.0/24 pointing to 192.168.1.254 on Site 3. There's no real reason
why it SHOULD work, but stranger things have happened before. The default
routes your using in the later sites should do the job, and indeed do up
until Site 3. It's possible that somewhere, somehow something got altered
by accident routing wise, but it SHOULD show up in the routing tables
(something like a 10.10.13.0 255.255.0.0 would REALLY confuse the
routing...) in at least some form.

This is an interesting problem (for me, at any rate, probably very
frustrating to you) so I'll bang my head on it for a bit and see if I come
up with anything interesting.

--
George Metz
Commercial Routing Engineer
[EMAIL PROTECTED]

"We know what deterrence was with 'mutually assured destruction' during
the Cold War. But what is deterrence in information warfare?" -- Brigadier
General Douglas Richardson, USAF, Commander - Space Warfare Center


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