IP Alias & IPtables, redirecting outbound traffic out specific interfaces

Hi All,

I have a fedorra box, it has one physical adapter from which I've used
IP aliasing to create 10 virtual interfaces. All of these interfaces
exist on the same subnet 10.209.170.140-150). What I would like to do
is when traffic enters a virtual interface ie 10.209.170.145 it needs
to leave via the same interface. At the moment it leaves by the first
defined interface ie 10.209.170.140, for instance if I have squid
running on 10.209.170.145, the request enters that interface but the
upstream request leaves via 10.209.170.140.

So am I right in assuming that I will need to use IPtables to do this,
or is there another way. If I have to use iptables, anyone want to
give me a hint as to how to do it, last time I touched iptables was
over 2 years ago.

Thanks

Paul

Heya,

You speak here of two different things.

1/ ensuring a connection coming on one IP address will be answered by
the same interface it came from even if the box has another default
route. That is _iproute2_ work (make one routing table per interface
and make a rule mapping each interface to each table. plus a default
route in each table specifying src ip)

2/ managing which way squid requests leave is not AFAIK really
manageable dynamically based on what interface request came from
(upstream request is _not_ in any way related to the client query at
the network / kernel level).

cheers