  function tryNextAgentKey() {
    if (curAuth === 'agent') {
      if (agentKeyPos >= agentKeys.length)
        return;
      if (++agentKeyPos >= agentKeys.length) {
        debug('DEBUG: Agent: No more keys left to try');
        debug('DEBUG: Client: agent auth failed');
        agentKeys = undefined;
        tryNextAuth();
      } else {
        debug('DEBUG: Agent: Trying key #' + (agentKeyPos + 1));
        stream.authPK(self.config.username, agentKeys[agentKeyPos]);
        stream.once('USERAUTH_PK_OK', onUSERAUTH_PK_OK);
      }
    }
  }