Old questing not yet resolved: Vbulletin Login

[taduyduc2003]

Im currently working on a site that require Vbulletin login as a medium of all other children sites...

BUT:

The problem is that one of the child site that im going to integrate is running on a different host. but it's still on the same main domain (child.xxx.com and forum.xxx.com) -> i already set the session domain to .xxx.com.

The solution of integrating VBB have been writen several times before, but almost all of them did not come with an explanation for any of their code, or they are used for local sites on the same host (require global.php)

I've done a lot of searches about this topic both on Google and Vbulletin websites, but no answer could be found. So i write this question.

I just simply want to ask how can I access the session on other webpage that i wrote above...

For example:
I have a forum on forum.xxx.com

and a site that running on other host and different ip, different server on fck.xxx.com . When the user type in the login on fck.xxx.com, they submited to forum.xxx.com/login.php and return back to the fck.xxx.com/login.php for validation purpose...

but how can i validate the session when i dont know how to access it.

You may find this question noob, but if someone could write a brief explanation for this, i will be very appreciated.

Thank you so much..

Regard....