Intranet IP detection for Node.js

intranetIp.js

(function() {
  var os = require('os'), interfaces = os.networkInterfaces(),
    ipFilter = function(addr) {
      // no need to match 169.254.0.0/16
      return !addr.internal && 
        (addr.family === 'IPv4' && addr.address.match(/^(192|172|10)\./)) ||
        (addr.family === 'IPv6' && addr.address.match(/^f(c0|e8)0:/) || addr.address.match(/^::1{0,1}$/));
    };

  for (var i in interfaces) {
    // ignore interfaces created by vm
    if (i.match(/^(VirtualBox|VMware)/)) {
      continue;
    }
    var ip = interfaces[i].filter(ipFilter);
    if (ip.length) {
      // fetch the first one
      // ip.pop() should work as well
      return ip.shift().address;
    }
  }
  // not found
  return 'localhost';
})();