Adventures in UPnP with node.js

Please also see:

• nat-upnp
• Adventures in UPnP on OS X
• Adventures in UPnP with cURL and netcat

Find your Internet Gateway (router) with a UPnP Search Broadcast

This will

1. Create a dgram socket bound to a random port
2. Send an HTTP-like M-SEARCH message to discover an IGD (your router)

* message is sent to 239.255.255.250:1900 (hard-coded as per spec)

3. Receives response from IGD from actual ip and dynamic port

* netcat would ignore such a response due to the ip mismatch

4. Prints the message to the screen
5. The Location field is what's important

UPnP SSDP Internet Gateway Device discovery example

wget https://raw.githubusercontent.com/coolaj86/holepunch/master/examples/upnp-ssdp-igd-discovery.js

'use strict';

var dgram         = require('dgram')
  , fs            = require('fs')
  , ssdpAddress   = '239.255.255.250'
  , ssdpPort      = 1900
  , sourceIface   = '0.0.0.0'         // or ip (i.e. '192.168.1.101', '10.0.1.2')
  , sourcePort    = 0                 // chosen at random
  , searchTarget  = 'urn:schemas-upnp-org:device:InternetGatewayDevice:1'
  , socket
  ;

function broadcastSsdp() {
  var query
    ;

  // described at bit.ly/1zjVJVW
  query = new Buffer(
    'M-SEARCH * HTTP/1.1\r\n'
  + 'HOST: ' + ssdpAddress + ':' + ssdpPort + '\r\n'
  + 'MAN: "ssdp:discover"\r\n'
  + 'MX: 1\r\n'
  + 'ST: ' + searchTarget + '\r\n'
  + '\r\n'
  );

  // Send query on each socket
  socket.send(query, 0, query.length, ssdpPort, ssdpAddress);
}

function createSocket() {
  socket = dgram.createSocket('udp4');

  socket.on('listening', function () {
    console.log('socket ready...');

    broadcastSsdp();
  });

  socket.on('message', function (chunk, info) {
    var message = chunk.toString();

    console.log('[incoming] UDP message');
    console.log(info);
    console.log(message);
  });

  console.log('binding to', sourceIface + ':' + sourcePort);
  socket.bind(sourcePort, sourceIface);
}

createSocket();

I've tested this against:

• Google Fiber NetworkBox
• Netgear AC ??? (TODO check model number)
• WRT54G-TM with DD-WRT
• WRT54GS with Linksys firmware

See nat-upnp for port-forwarding.

It will not work with

• Apple Airport Extreme
• Apple Airport Express

These use Zeroconf. If you know how to discover the ip address of an Apple router, I'd love to hear about it in the comments.

See nat-pmp for port-forwarding.

By AJ ONeal


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