  constructor() {
    super();

    this.config = {
      host: undefined,
      port: undefined,
      localAddress: undefined,
      localPort: undefined,
      forceIPv4: undefined,
      forceIPv6: undefined,
      keepaliveCountMax: undefined,
      keepaliveInterval: undefined,
      readyTimeout: undefined,

      username: undefined,
      password: undefined,
      privateKey: undefined,
      tryKeyboard: undefined,
      agent: undefined,
      allowAgentFwd: undefined,
      authHandler: undefined,

      hostHashAlgo: undefined,
      hostHashCb: undefined,
      strictVendor: undefined,
      debug: undefined
    };

    this._readyTimeout = undefined;
    this._chanMgr = undefined;
    this._callbacks = undefined;
    this._forwarding = undefined;
    this._forwardingUnix = undefined;
    this._acceptX11 = undefined;
    this._agentFwdEnabled = undefined;
    this._remoteVer = undefined;

    this._protocol = undefined;
    this._sock = undefined;
    this._resetKA = undefined;
  }
The software constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.