-------- Message original --------

> Hi
> 
> I have a Adsl (pppoe)  connection with 2 ips.
> 

Tell us more about these 2 IP addresses. How are they assigned?

What I guess:

You have 2 IP addresses and get one static IP address via PPPoE. The 
other one is a 'spare' address' which is not assigned to any interface: 
you have to configure it by hand.

Is this right?

I don't see why the other IP address could not be used as alias for the 
WAN interface...

Just give it a try ;-)  See my previous post and replace x.x.x.A with 
your actual address and sis0 with your actual interface name. That's 
just it!

Notice: DMZ and NAT/Firewall setup are another topic ;-)

-- Vincent