u2nl

u2nl is a powerful software application that offers a universal transparent HTTPS proxy tunnel to its users. What this means is that it acts as a middleman and tunnels all connections transparently via an HTTPS proxy, using the CONNECT command to the internet, without requiring another host on the internet. The only requirement is that the HTTPS proxy allows these CONNECT connections. It provides full connectivity to a Linux host when everything except the HTTP proxy is blocked by a firewall.

Using u2nl is easy. The first step is to identify the IP address and port of the HTTPS proxy being used for tunneling. Once confirmed, ensure that the Linux host forwards all connections to a port, u2nl is listening on. The following command can be used for the same:

# iptables -t nat -A OUTPUT -p tcp -d ! -j REDIRECT --to-port

Replace OUTPUT by PREROUTING if the Linux computer is only acting as a gateway. After replacing the placeholders with the actual IP address/hostname of the proxy host and the port assigned to be used by u2nl, start the application by executing the following command:

# u2nl

The port of the HTTPS proxy (normally 8080 or 80) and the previously assigned port of u2nl should be filled in to execute the command. The tunnel is ready to use once these steps have been carried out.

The latest version of u2nl includes an improved Makefile. This software application is highly recommended for users looking for a seamless and efficient HTTPS proxy tunneling solution.