If my main site where customers log in is www.mysite.com, Will the SIP enable them to not have to login to forums hosted on a different domain (and possibly different server) such as forums.mytechsupportsite.com ?

Hi Iderdik,

The sip utilizes cookie to perform auto login, which means the info cannot be read across domains. However, with some clever programming it can be done. Let me give you an example.

1) you create a table in the db to hold 2 values, member ID and a hash value (maybe an MD5 of memberID + date)
2) once member is logged in using the SIP on the main site, store the member ID and the hash value in the table
3) redirect the member to a page located on the mytechsupportsite.com which also utilizes the SIP, with the hash value as the querystring
4) on this specific page, read the hash value and pull the member ID from the table created in 1), and then delete the record
5) base on the member ID, pull the login and password from the forum database and use the SIP to perform login (because the SIP takes login and password), which then creates a cookie that is readable on the second site.
6) at the end of the operation, you can either redirect the user back to the main site or do whatever you see fit.

ASPPlayground.net Developer

If you do have access to the back end server code of both domains another approach might be to use a trick such one of those found in the net for sharing session state between the asp and asp.net pages of a single web site.
 
Certainly, this one might not be so efficient as that suggested by Samuel but can be used, for example, for getting (long) session variables from another site.