Controlling HTTP & SMTP IP flow for 3 NIC's

[Craig White]

On Wed, 2008-01-23 at 09:53 -0800, Tim Alberts wrote:
> A little background first..I run 2 servers, mail and web.  The mail 
> server is down for hardware problems.  I'm running both email and web on 
> one server.  The web server has 3 network interfaces 1 for public email, 
> 1 for public web, and 1 for private network.  I use 3 cards because the 
> router I connect to the internet won't recognize multiple IP's for a 
> single hardware MAC.
> 
> The problem is, that my email messages seem to be going out the web 
> network interface.  This is typically not a problem except for the 
> reverse DNS lookup  fails which at least one domain (Comcast.Net) rejects.
> 
> My question therefore is, how can I route my sendmail traffic to go out 
> the correct ethernet interface?  I'm sure I'll need to do the same for 
> the web traffic so web site spoofing alarms are triggered.
> 
> I have told sendmail to listen to the correct interfaces, but that 
> apparently doesn't mean only write to those interfaces.  I don't see how 
> to control this by setting up my routes and I can only really think of 
> ways to block it in IPtables, not re-route it.
----
assuming that /etc/sysconfig/network has GATEWAY=SOME_IP_ADDRESS then
adding GATEWAYDEV=eth0 (or whatever) should identify which to use.

Craig