Spanning Login Across Domains

[DraX]

I run mutliple sites, that are all part of the same network. The forums are modified to give the appearance of being different, but use the same database (i.e. using virtual redirects and aliases).

forums.sitename1.com goes to forumsite.com and the specified category for sitename1.com, and so on and so forth throughout the multiple sites...

It is completely transparent to the user, as they still see forums.sitename1.com in their browser (which is giving me a hell of a time trying to keep the login across the domains).....

Any ideas on how I should go about this?

[NTLDR]

As far as I am aware you can't, you can only span the cookie across an entire single domain and if I am correct this can't be changed. Perhaps someone could confirm this?

[DraX]

Hmmm.. well, in that case, can vBulletin maintain user session by passing the session id through the Query string without cookies?

I've already figured out how to get vBulletin to detect what domain it was requested from, so that if it is not correct (determined by what style is in use), it will redirect the user to the same thread on the other domain name.

What would be the variable I attach to the querystring of the redirect url to send the session id with it, so that the server knows it's the same session? (i.e. ?sess_id=e647u5e6436f4326)