Security / Login issue

[Remco]

Hi,

I'm working on a secure webportal, a simple representation of my folders:

Root
->Users
->Admins
->Printing

If somebody attempts to access a sub folder he or she will be redirected to
the Logon webpage (Forms security in web.config)

Based on roles I would like to give persons permissions to view pages.

users are entering the website as www.website.com
admins as admin.website.com
print companies as repro.website.com

Can I use the Server Variable "SERVER_NAME" to redirect the different types
of users savely to their part of the website after authorizing them?

Are there any recommendations or suggestions related to this issue?

Thanks in advance,

Remco