I've got several sites that I'd basically like to have the same user system for.
One of the sites runs XenForo, the others all run Codeigniter, or systems built on Codeigniter (e.g PyroCMS).
I need to somehow be able to let a user login on any of the sites with the same username/password combination, in addition to be able to register.
I know there are a number of ways of going about this, such as an OpenID server, however I'm not 100% sure which is best for my situation given that I'm using two systems that arent exactly going to play nice together.
I'm not too bothered about having it autologin across all sites at once, but just dont want people to have to use multiple different credentials.
Would I be right in thinking something along the lines of a central OpenID server, with openid authentication on the 'slave' sites would be my best option?
I'd ideally like to use the XenForo user table as the 'master' user table in this situation.
Any input or suggestions would be greatly appreciated.
I wrote one here a while ago, I've not updated it in a while though should still be good :
http://www.jeremyhutchings.com/2010/12/xenforo-and-codeigniter-intergration.html