External site SSO with vbulletin

[plongeur.com]

Hi,

I have 2 sites :
- one (lets call it site1.com) with my vbulletin instance.
- the other (let's call it site2.com) without a forum but with other content.

I would like my users from site2.com to be able to log in on this site with their vbulletin credentials from site1.com. Idealy they would be logged in on both site once identified in either one of them.

Do you think this is feasable ?

[Master Of Unive]

Are your two sites on the same server?

[plongeur.com]

I could install them on the same server, this is not a big deal.