This tool is meant to run between a NAT rule intercepting HTTPS traffic and an HTTP CONNECT proxy.
It listens for TCP connections (sent by NAT) and waits for the ClientHello message to appear. The SNI is then extracted and a corresponding HTTP CONNECT request is sent to the upstream proxy. tls2httpconnect and the proxy then act together as simple TCP relays between the client and the remote endpoint.
This essentially allows for transparent HTTPS proxying on routers. For an all-in-one solution, you can also find similar functionality in Squid (SslBump) and Apache Traffic Server.
tls2httpconnect can be built using cargo:
$ cargo build --release
You can then install it as you please, for instance using install:
$ sudo install -m 0755 target/release/tls2httpconnect /usr/local/bin
For quick usage instructions, run tls2httpconnect -h.
When running on the router performing NAT, a typical rule would be:
iptables -t nat -A PREROUTING -p tcp --dport 443 -j REDIRECT --to-port 8888
This effectively captures all incoming traffic to TCP 443 and redirects it to local port 8888, where tls2httpconnect is waiting.
tls2httpconnect is released under the terms of the AGPL.