我会尝试使用ssh2来管理我在本地主机上的ubuntu系统，如果能正常工作我会尝试通过网络连接进行管理。但是第一步我在localhost上连接到自己有问题
$connection = ssh2_connect('localhost', 22);
结果
Warning: ssh2_connect(): Unable to connect to localhost on port 22 in /var/www/system/index.php on line 6
Warning: ssh2_connect(): Unable to connect to localhost in /var/www/system/index.php on line 6