[clue-tech] choosing a default route based on traffic type?

[David L. Anselmi]

Jim Ockers wrote:
> Can anyone out there think of some other way to route particular (as
> determined by layer 4 and above) traffic (bi-directionally) over one
> network and through one "default" gateway, and all other traffic through
> another "default" gateway? Is the only way to do this via iproute2 and
> fwmark? We are open to very clever suggestions...

So TOS seems like it would work instead of fwmark.  But it looks like that uses mangle too.

Is there any way you can set the source IP (as in NAT) at the point that you would use fwmark?  In 
other words, instead of noticing the destination port and setting a mark that can later be used to 
do NAT, can you do the NAT right then?  Or can you move the "what dest port is it" check to later 
when you're doing the NAT anyway?

Can you use queuing disciplines?  They seem to handle destination ports and don't use iptables.  But 
I'm not clear on whether you can put different queues on each interface and then drop any old packet 
into either queue (I'd guess that if you can iptables can figure out how to NAT for each interface).

Good luck!
Dave