I have been trying to get a multisite login system working. For example, a user goes to site1.com, logs in using login.site1.com, and is logged in on site2.com as well. I have tried cookies, but site2.com cant access site1.com cookies. I'm stuck with sessions, which I can't figure out, when I pass the session id through the url, I get a session id too long error. I've read that you can use mysql to do that, but how would you do that?