I\'ve been working with Socket.IO for a few days and it\'s been both extremely exciting and even more frustrating. The lack of current documentation/tutorials has made learn
The excellent passport framework for express uses secure cookies to validate identity. There is even a module to access it from socket.io.
If you can install a key-value store like Redis on your node server, you can access it remotely from your php server using a Redis client like Predis. All you have to do is updating the remote session store on node server when a new login/logout happens in your php server.
Check this post for details: Authenticate user for socket.io/nodejs