It's been almost a decade since I've looked at ASP/.NET code. I'm pretty inexperienced in this arena but my new employment has forced me to dive back into it.

The project:
I've been given the task of finding a way to authenticate users on our Intranet site via Active Directory to determine if they can access certain parts of the site. As it stands now, users are forced to login to certain sections with their network login. Some sections of the site are off limits to some users, yet they can still see the navigation links to those sections.

The goal:
The ideal situation is to have the Intranet recognize the primary user group each visitor is a member of in Active Directory and not display the links to the sections they do not have permission to access. I'd like to code it so that once a user opens the Intranet site in a browser, their windows network login info will be recognized.

There are two situations that I have to plan for - local and remote users...

The first situation:
In the office, the users will login to their machine with their network login. The intranet would need to capture this login when it's opened so that the navigation can be shown based on their network permissions.

The second situation:
Our users can access our Intranet site remotely by way of a specified URL which asks them for their network login. Once they enter their login, they can access the Intranet as if they were in the office. In this situation, since they're being prompted for authentication right up front, I would think it would be easier to capture that login info and keep it on file so that certain links are not displayed for sections they do not have access to.

The navigation is basically a simple server side include html file. It's not dynamically generated and it's not set up around the directory structure of the site. I'm hoping there is some code I can wrap around each navigation link that will do the necessary checks against Active Directory in order to show the link or not show the link. Also, I'm sure I'll have to add code to the top of each page that will store the session (user's info). I just need to be pointed in the direction where I can find this code and learn some basics of what I'm trying to accomplish, as I'm completely unsure where to start and I know almost nothing about ASP coding.

If there was some code (or script) that anyone could link to or post, I'd greatly appreciate it. Please forgive any stupid questions I'm asking. And please assume I know nothing about ASP when replying - I've been working mostly in PHP the last few years.

Thanks in advance!