Multiple PPP IPForwarding...

We are trying to set up two PPP's, to two different ISP's, one of which (ppp1) will carry all of our LAN's internet mail (smtp -25, pop3 -110) traffic, and the other (ppp0) the balance of our internet traffic (http, ftp, etc.)

The mail (ppp1) connection is full time, the "rest" (ppp0) is dial-on-demand (diald, already working fine).

We already have the "mail only" IPForwarding rules sorted, so we are looking for the "exclude mail" rules, as well as the rules to ensure that traffic is routed to the correct port.

An extra problem is that it seems that if you have ppp0, then ppp1, both are recognised, but if you only start ppp1, the system thinks it is ppp0!

We are running RH5.0, 486/66, 24Mb, 1 x NE2000 (eth0), and 2 x modems.
Spikeman050198Asked:
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mrauschCommented:
> looking for the "exclude mail" rules, as well as the rules to

I suppose with "mail only" rules, you allow connections from the
outside to port 25 on your side, and from your side to port 25
on any machine on the outside, denying the rest. When you want
to disallow mail traffic (that's what you problaby mean with
"exclude mail" rules) just invert that. Deny traffic to/from
port 25 and allow all the rest.

> ensure that traffic is routed to the correct port.

Here you want a policy-based routing. Later 2.1 kernels are
able to do this, but these development kernels are probably not
something you want to use for stability reasons.
Probably the easiest way is to set up another box which carries
the dedicated mail ppp link and let your first machine forward
all mail traffic to the second one. On the first on, you now have
an default route via what was ppp1 before, and mail is forwarded
to box #2, which has an default route to what was ppp0 before.
If this second box is no choice, perhaps you can ask your ISP
to do primary MX for you, and let his mail server relay the
data to you.

Re. your last problem, you can specify the interface address
instead of the interface name in the ipfwadm rules, that is
just give "ipfadm <thisandthat> -V address.of.ppp0.interface"
instead of "ipfwadm <thisandthat> -W ppp0"


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Spikeman050198Author Commented:
We still need a bit more information on this one...
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