Configuring IIS to use IP then Authentication for access

From: Jason Hebron (Jason.Hebron@vuw.ac.nz)
Date: 10/17/02 

From: "Jason Hebron" <Jason.Hebron@vuw.ac.nz>
Date: Fri, 18 Oct 2002 10:37:23 +1300

Hi
I need to setup an IIS5 web server so that when a user on a specific set of
subnets connects to it they get in straight away using the IUSR account, if
they aren't on that range of IP addresses they are then forced to
authenticate against a domain

So process is
client connects to site
if they are on an "allowed" range of ip addresses they get on straight away
using IUSR account
If not on that allowed range of IP addresses they are forced to authenticate
using a userid and password

Any assistance greatfully received
PS please email me as well as group, thanks