Query DB - Session Logged in?

[m002.p]

Hello!

I am after a way to detect using a mysql query whether a user on my vbulletin forum is logged in or not.

Basically, I have a few external scripts on the same server that instead of using a login system for, would like to simply add a query to the php files concerned and detect whether a user is logged in at the forums or not. If they are, then proceed otherwise refer to a denied page.

I have worked out the rest of the queries involved here, and would appreciate anyone who knows or can provide me with the MYSQL query to check the login status from the forum table.

In addition, does anyone know whether a users IP could be faked? I get a users IP and use it to identify them so I am wondering if this is not fail safe and a hacker could potentially fake or mask a users ip and appear to be them?

Any assistance is appreciated.

Matt