Authenticate user for socket.io/nodejs

I have a php login, the user puts in a username/password, it checks the mysql db against the login information. If authenticated a session is created via php and the user can now access the system with the php session. My question is once they authenticate via php/session what would be the process to authorize the user to see if they have the right login permissions to access a nodejs server with socket.io? I dont want the person to have access to the nodejs/socket.io function/server unless they have authenticated via the php login.