Apparently, HTTP proxies have a command CONNECT, that lets you open a TCP/IP connection to an arbitrary host and port. This is intended for HTTPS. Now, most proxies probably limit this to 443 only, HTTPS port. So, presumably all those clients like ICQ that let you run over HTTP proxy - they use this, and have a ICQ server running on port 443. Thus allowing people to use it behind corporate firewalls. So, we need a HTTPProxy transport that will do this automatically for clients, along with a SOCKSv4 transport and eventually a SOCKSv5 transport. proxy = HTTPProxier("proxy.isp.net", 8080) proxy.clientTCP("www.example.com", 443, myProtocolInstance) # cool, huh?