Download of TCPRelay 1.0 for Mac was available from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe. The program lies within Internet & Network Tools, more precisely General.
From the developer:
TCPRelay is a command line utility written in java designed to relay TCP connections for servers. What does that mean? It means that you can run a server on your machine, be behind a firewall and God knows what else, and still be able to host a server (as long as outgoing connections are allowed). It requires only that you have access to another computer (called a remote relay) that does allow servers, and for that machine to have java installed.