A basic TCP proxy written in node.js

tcpproxy.js

var net = require("net");

process.on("uncaughtException", function(error) {
    console.error(error);
});

if (process.argv.length != 5) {
    console.log("Usage: %s <localport> <remotehost> <remoteport>", process.argv[1]);
    process.exit();
}

var localport = process.argv[2];
var remotehost = process.argv[3];
var remoteport = process.argv[4];

var server = net.createServer(function (localsocket) {
    var remotesocket = new net.Socket();

    remotesocket.connect(remoteport, remotehost);

    localsocket.on('connect', function (data) {
        console.log(">>> connection #%d from %s:%d",
                server.connections,
                localsocket.remoteAddress,
                localsocket.remotePort
                );
    });

    localsocket.pipe(remotesocket).pipe(localsocket);
});

server.listen(localport);

console.log("Redirecting connections from 127.0.0.1:%d to %s:%d", localport, remotehost, remoteport);