Node.js - forward all traffic from port A to port B

Question

I'm trying to forward all traffic from port 6999 to port 7000 (I know I could use iptables, but the idea is to use Node.js to do some packet inspection).

Here is the code I have sofar:

var net=require('net'); var compress=require('./node-compress/compress');  var ip='172.16.1.224'; var ipPort=6999; var opPort=7000;  var output=net.createServer(function(connOut){         var input=net.createServer(function(connIn){                 connIn.pipe(connOut);         });         input.listen(ipPort,ip); }); output.listen(opPort,ip); 

It just does not seem to work. When I do a tcpdump on port 7000, nothing shows up. Anyone have any suggestions?

Many thanks in advance,

Answer 1

Here's my go at it:

Supports giving the "from" and "to" from command line, and supports remote machines.

var net = require('net');  // parse "80" and "localhost:80" or even "42mEANINg-life.com:80" var addrRegex = /^(([a-zA-Z\-\.0-9]+):)?(\d+)$/;  var addr = {     from: addrRegex.exec(process.argv[2]),     to: addrRegex.exec(process.argv[3]) };  if (!addr.from || !addr.to) {     console.log('Usage: <from> <to>');     return; }  net.createServer(function(from) {     var to = net.createConnection({         host: addr.to[2],         port: addr.to[3]     });     from.pipe(to);     to.pipe(from); }).listen(addr.from[3], addr.from[2]); 

(save as proxy.js)

To forward from localhost:9001 => localhost:80

$ node proxy.js 9001 80 

Or localhost:9001 => otherhost:80

$ node proxy.js 9001 otherhost:80 

(This was based on Andrey's answer, thanks!)