WebSocket connections generally work even if a proxy or firewall is in place. This is because they use ports 80 and 443 which are also used by HTTP connections.
In some situations WebSocket connections are blocked over port 80. In this case a secure SSL connection using WSS over port 443 should successfully connect. If this is not the case please contact Pusher support.
The destinations and ports used by Pusher clients are as follows:
If pusher-js is used and it is a version before 3.0.0 then if Flash is required as a fallback (e.g. the browser does not natively support WebSockets) the following addresses and ports may attempt to be used via a direct TCP connection:
ws.pusherapp.com port 843
ws.pusherapp.com port 80