出错-php使用ssh2时报错，InvalidMAC

Warning: ssh2_connect(): Error starting up SSH connection(-4): Invalid MAC received in /var/www/html/ssh.php on line 10
Warning: ssh2_connect(): Unable to connect to 192.168.30.72 in /var/www/html/ssh.php on line 10
Warning: ssh2_auth_password() expects parameter 1 to be resource, boolean given in /var/www/html/ssh.php on line 12 Cannot log in

报出这几个错误。。

代码如下
$con = ssh2_connect($host, '22');
if (ssh2_auth_password($con, $user, $passwd)) {
$stream = ssh2_exec( $con, "ls" );
print $stream;
} else print 'Cannot log in';