portforward/lib/portforward.js

A portforwarding service, support both local port forwarding and remote port forwarding

/*
    Author : GYZheng, http://github.com/iamgyz
    Feature : A portforwarding service, support both local port forwarding and remote port forwarding
    Enviornment : nodejs
    Install: npm install -g portforward
    Usage: portforward <from> <to>
    Update date : 2015.06.17
*/
var net = require('net');

function start(){
console.log('============PORTFORWARD SERVICE BY GYZHENG============')
//Handle argument list
var localPort,forwardPort,forwardAddr = '127.0.0.1';
if(process.argv.length <= 5 && process.argv.length >=4){
    localPort = process.argv[2];
    forwardPort = process.argv[3];
    if(process.argv.length==5)
        forwardAddr = process.argv[4];
}else{
    console.log('Usage');
    console.log('#Mode 1: Local forwarding')
    console.log('portforward <from> <to>');
    console.log('Example: portforward 9999 80, which means forward port 9999 to port 80');
    console.log('#Mode 2: Remote host forwarding');
    console.log('portforward <from> <to> <remoteHost>');
    console.log('Example: portforward 9999 80 whatismyip.org, which means forward port 9999 to whatismyip.org:80');
    return;
}

//Create server
var server = net.createServer();
//handle server event
server.on('connection', function(sock) {
    console.log('[INFO] New client connect from ' + sock.remoteAddress +':'+ sock.remotePort);
    console.log('[INFO] Step1 : Connect to forwarded address and port...');
    var to = net.createConnection({
        host: forwardAddr,
        port: forwardPort
    });
    to.on('connect',function(){
        console.log('[INFO] ======> Connect to forwarded address & port successfully!');
        console.log('[INFO] Step2 : Start to forward the socket data!')
        to.pipe(sock);
        sock.pipe(to);
    });
    to.on('close',function(){
        console.log('[INFO] Forwared port close the connection');
    });
    to.on('error',function(err){
        console.log('[ERRO] Error occur! Connection fo forwarded port closed');
        if(err.code == 'ENOTFOUND'){
            console.log('[ERRO] Remote host is not exist! Please check your host address again!!');
        }else if(err.code =='ECONNREFUSED'){
            console.log('[ERRO] Forwarded Port is not open! Please check your port again!!');
        }else{
            console.log(err);
        }
        console.log('[INFO] Close client connection due to the errors')
        sock.destroy();
    });
    sock.on('close',function(){
        console.log('[INFO] Client close the connection to forwarded port');
    })
});
server.on('error',function(err){
    console.log('[ERRO] Error occur! Are you try to bind the already-used port?');
    console.log(err);
});

//Listen on local port
server.listen(localPort,'0.0.0.0',function(){
    console.log('[INFO] Listening on ' + server.address().address +':'+ server.address().port);
    console.log('[INFO] Forward target '+forwardAddr+':'+forwardPort);
    console.log('[INFO] Ready for handling the port-forwarding!');
});
}//function start
exports.start = start;