Sunday, 20 November 2011

How to access remote server using PHP SSH?

To remotely access a server in PHP provides a full library of functions called SSH2 functions. You can get the manual from the link. You'll get most of the information from the manual itself but it also leaves the user with some questions which are unanswered. Here i am just trying to explain the same in some better way..

Simple Example : 

<?php
    if (!function_exists("ssh2_connect"))
        die("function ssh2_connect doesn't exist");
    if(!($con = ssh2_connect("www.example.com", 22(port number)))){
        echo "fail: unable to establish connection\n";
    } else {
        if(!ssh2_auth_password($con, "username", "password")) {
            echo "fail: unable to authenticate\n";
        } else {
            echo "okay: root logged in...\n";
            $stream = shell_exec("mkdir /var/www/shiv");
        }
    }

?>

Important Notes :

1) If you are logged in as a normal user(not root user) then you can't change user and login to the root or super user using these function. You can use su as a command but can't enter password as a command because server only allow the user to enter password through standard input device. For example if you are trying like this:

$stream = shell_exec("su; superuser password");

then it won't work.

2) If you want to run multiple commands then you have to use single shell_exec() function for that. For example :

$stream = shell_exec("mkdir /var/www/shiv; mkdir /var/www/modi");

It would create two sub-directories named 'shiv' and 'modi' in /var/www/ directory.


while


$stream = shell_exec("mkdir /var/www/shiv");
$stream = shell_exec("mkdir /var/www/modi");

commands won't work, because command n shell environment will not be remembered during the execution of command n+1.If you want the shell commands to be working while depending on each other in terms of environment, you should put several commands in a unique ssh2_exec().


Now you can run any number of commands on remote server. You can also use ssh php function to download, upload files etc....

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