We have an SControl which will be used by people who are not SFDC users.

There is a separate authentication procedure (.NET) which uses dedicated SFDC licence. This procedure retrieves SFDC sessionid (through the login call to SFDC Web Service API) and then redirects user to the actual SControl using frontdoor.jsp

https://emea.salesforce.com/secur/frontdoor.jsp?sid={session-id-here}&retURL=/servlet/servlet.Integration%3fic=1%26lid=01N200000008nA1

When the whole procedure opens in a new browser window everything is fine but if we try to embed the authentication/redirect page within a SharePoint Page Viewer Web Part (which uses an IFrame) then we get redirected to the SFDC login page.

We are experiencing the same problem as this person:

http://community.salesforce.com/sforce/board/message?board.id=NET_development&message.id=1848&query.id=94310

i.e. "The cookie for the user session in asp is not allowed when set in an IFrame from another domain"

Unfortunately enabling cookieless sessions as in the example has not resolved the issue for us.

So does anyone have any ideas on how I can embed the web-service authentication page (.net) and forward to the SControl within a SharePoint web part or IFrame?

Many thanks