 <p>As of version 1.5.1, I'm able to access all the sockets in a namespace with:</p> <pre><code>var socket_ids = Object.keys(io.of('/namespace').sockets); socket_ids.forEach(function(socket_id) { var socket = io.of('/namespace').sockets[socket_id]; if (socket.connected) { // Do something... } }); </code></pre> <p>For some reason, they're using a plain object instead of an array to store the socket IDs.</p>