This is deprecated, python performs poorly and with just 100 lines I created a simple and extremly fast (same as udp) syn/syn-ack proxy in Golang meant to be used with a vpn. Search for it.
I created it because it bypass all mobile carriers' firewalls even when you don't have a balance or an internet plan (only if the carrier redirects you to an http page when you try to navigate on the WWW, but this works also when http host header injection fails and btw it is faster since it practicaly uses udp). Unfortunatly to make those strange packets it uses raw sockets and in Android you need root access for that, but it works.