Apache and IIS

Hi folks,
My english is very bad, so be pacient with me...

I have an Linux server running Apache, this server has only one Valid IP (200.207.51.y) and it's connectec at a ADSL Brazilian Service.

I have an Win2k Server runnig IIS 5.0, this server has an Invalid IP (192.168.9.x) and the IIS is configure to use the port 81

Well, i must allow to some costumers to get access in the IIS, so I used the ipfwadm to redirect the connections on the Valid IP to the Invalid IP at port 81.

It's work, but I need to authenticate the user who will access the IIS, but i can't do that with the IIS authetication configuration, because if I enable the Basic Authentication, it will be required to my local (lan) users...

I was think if is possible to make the authentication in the Apache server, so redirect it to the IIS.

Somebody can help me ?

Please, be free to correct my bad english and I hope that I made myself clear.

Thanks !
Edgar (BrazilianGuy)

well, i guess you got several options to choose from :

- you can put some rewrite rules in place in your Apache config file, so it will redirect and authenticate everybody who is gonna access your IIS server. of course you have to have a dedicated location on the Apache box, so it will now what requests should be redirected

- you can use a so called forwarding proxy on the linux machine ( Squid will do ). it can authenticate and forward your users to the IIS box. I guess it's more secure than the first option. Unfortunatelly it has it's drawback as well. You have to decide which server will run on port 80 : Squid or Apache.