Usually the SSH package support HTTP(S) proxies and this should be sufficient to overcome most known proxies.
However, there are existing very difficult cases, where the proxy environment can not be properly recognized, is hidden from third party software or the target servers are behind reverse proxies.
For such difficult cases the software contains Non-SSH solution called "Rescue mode".
If you can establish HTML5 connection, then you can be sure this software will help you to establish native socket connections through Websocket(FF, Chrome, Opera, IE10 etc) or XHR (IE6-IE9).
Be careful, some proxies allow Websocket/XHR traffic only via HTTPS layer, so use https address instead of http.
If proxy does not ask for proxy authentication and you can access pages via browser:
If proxy requests proxy authentication and you can access pages via browser: