SSH功能不存在

I try create user with SSH, but in website I get this error: function ssh2_connect doesn't exist. What can I do?

My all code:

    <?php
if (!function_exists("ssh2_connect")) die("function ssh2_connect doesn't exist");
if (!($con = ssh2_connect("77.241.202.58", 22))) 
{
    echo "Klaida
";
} 
else 
{
    if (!ssh2_auth_password($con, "root", "pass")) {
        echo "Negalima
";
    } else {
        // allright, we're in!
        echo "Prisijungta
";

    }
}
?>

You are missing OpenSSL or libssh2 on your server: http://www.php.net/manual/en/ssh2.requirements.php

My recommendation: use phpseclib, a pure PHP SSH2 implementation. Trying to install libssh2 is quite difficult and phpseclib is often just plain better anyway:

https://stackoverflow.com/a/14305875/569976