docs: function (opts) {
          EventEmitter.call(this);
  
          this.host = opts.host;
          this.port = this._generateRandomPort(opts.ports);
          this._sshPort = opts.sshPort || DEFAULTS.SSH_PORT;
          this.user = opts.user;
          this.proxyHost = util.format('%s:%d', this.host, this.port);
          this.proxyUrl = this.proxyHost; // deprecated, use proxyHost
          this._localPort = opts.localport;
          this._connectTimeout = opts.connectTimeout || DEFAULTS.CONNECT_TIMEOUT;
          this._tunnel = null;
          this._tunnelDeferred = q.defer();
          this._closeDeferred = q.defer();
      }