Linux Firewalling

[Longman]

* william pink wrote:
> I use virtual interfaces for my firewalls I am intrigued on why you
> need physical NIC's?

I use IP aliasing for configuring more than one IP on the same network
on one NIC but I've never done this where I need to connect to lots of
different networks - only where I've wanted to run different services on
different IPs but not use DNAT.  If you need to connect NIC 192.168.1.1
to router 192.168.1.2 and NIC 192.168.4.1 to router 192.168.4.2 are you
saying rather than connecting them directly you use IP aliasing and a hub?

How do I physically connect the routers 192.168.1.2 and 192.168.4.2 to
my firewall if I'm using virtual addresses?