app.js

## app.js
var	express = require('express'),
		app 		= express.createServer(),
		sio 		= require('socket.io'),
		redis 	= require("redis"),
    client 	= redis.createClient(),
		io			= null;

/**
 *	Used to parse cookie
 */
function parse_cookies(_cookies) {
	var cookies = {};

	_cookies && _cookies.split(';').forEach(function( cookie ) {
		var parts = cookie.split('=');
		cookies[ parts[ 0 ].trim() ] = ( parts[ 1 ] || '' ).trim();
	});

	return cookies;
}

app.listen(3000, "localhost");
io = sio.listen(app);

io.configure(function () {
  function auth (data, fn) {
  	var cookies = parse_cookies(data.headers.cookie);
  	console.log('PHPSESSID: ' + cookies.PHPSESSID);

		client.sismember('sid', cookies.PHPSESSID, function (err , reply) {
			fn(null, reply);
		});
  };

  io.set('authorization', auth);
});

io.sockets.on('connection', function (socket) {
  socket.emit('access', 'granted');
});

## client.php
<?php

session_start();

echo "<h1>SID: " . session_id() . "</h1>";
?>
<html>
<head>
	<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.6.1/jquery.min.js"></script>
	<script src="http://localhost:3000/socket.io/socket.io.js"></script>
</head>
<body>
	<p id="text">access denied</p>
	<script>
		var socket = io.connect('http://localhost:3000/');
		socket.on('access', function (data) {
			$("#text").html(data);
		});
	</script>
</body>