What alternative is there to writing a TCP/IP data relay?

I am about to write a tcp/ip data relay - application that passes a one way stream of data from one host/port to开发者_开发百科 another host/port. Initially it will be generic, but later on i will customize it to the need of a specific business request.

I am guessing that something generic already exists out there so my question is:

Has anyone used a third party (preferably open source) data relay in a production environment, if so what is, and do you recommend it?

Any platform is fine.

Thanks.

GNU netcat can be configured to do this, and is open source, multi platform.

I am the author of yProxy, which can be used as a transparent TCP proxy server. I use it in production as a simple transparent proxy.

I don't know of any open source proxies, but that's what you're looking for. Look for an open source "transparent proxy server", also sometimes called "tunneling".

A transparent tcp proxy or tunnel is about the easiest thing to write if you're familiar with socket programming. The hardest thing about it is dying gracefully. There are so many ways that you can lose your connection, you must ensure that your program can handle all eventualities.

I've used Delegate for proxying in production use, it's been solid.