Roberto Pereyra wrote:
> Hi all !!
> 
> I have two internet  links.
> 
> I would like mark and route all p2p and junk traffic with  a second
> link (not the default).
> 
> Can I use shorewall for it ?
> 

Yes and no.

For that P2P traffic that you can identify up front by protocol and port, you
can create marking rules and route the traffic accordingly. For P2P traffic
identified by ipp2p, in general you cannot change the routing.

Let's take a look at why (and this really has nothing to do with Shorewall).

Suppose that you have two internet connections to two different ISPs. The
external IP addresses are a.b.c.d and w.x.y.z for the links to ISP1 and ISP2
respectively. Further suppose that you use SNAT/MASQUERADE through both
interfaces to allow your internal clients internet access. Suppose that you want
P2P traffic routed out through ISP2 and all other traffic out through ISP1.

If internal system 192.168.4.22 establishes a connection to TCP port 80 at
i.j.k.l, that connection is routed out of ISP1. So the system at i.j.k.l accepts
a connection from a.b.c.d. If later on, the ipp2p module discovers that this
connection is later a P2P connection, what happens if it suddenly switches the
connection to ISP2? Now, we will be sending packets with source IP a.b.c.d out
through the link to ISP2. Since that isn't an address assigned to you by ISP2,
that ISP can reasonably ignore (drop) that traffic. But even if ISP2 doesn't
drop the traffic, only the outbound part of the connection would go through ISP2
-- traffic from i.j.k.l to a.b.c.d will continue to be handled by ISP1.

 -Tom
-- 
Tom Eastep    \ Nothing is foolproof to a sufficiently talented fool
Shoreline,     \ http://shorewall.net
Washington USA  \ [EMAIL PROTECTED]
PGP Public Key   \ https://lists.shorewall.net/teastep.pgp.key

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