Execute commands on remote machine via PHP

Question

To give background on my environment:

I have 3 machines A, B & C

A = Webserver, running a php website which basically acts as an interface for B & C

Answer 1

I recommend SSH2 to execute commands on remote machine. You can use pecl to install it easily. After that, you may use ssh2_exec() function to execute your commands and ssh2_fetch_stream() function to get stderr. Example codes are listed below:

// start connection
$connection = ssh2_connect("your remote ip address", your port);
ssh2_auth_password($connection,"your user name","your passwd");

// connection established, start to execute codes
$stream = ssh2_exec($connection, "your command");  
$errorStream = ssh2_fetch_stream($stream, SSH2_STREAM_STDERR);

// block 2 streams simutaneously
stream_set_blocking($errorStream, true);
stream_set_blocking($stream,true);

// write stdout and stderr to log file
file_put_contents("your log file-path", date('Y-m-d H:i:s')."\nError: ".stream_get_contents($errorStream)."\nOutput: ".stream_get_contents($stream), FILE_APPEND)

// close 2 streams   
fclose($errorStream);
fclose($stream);

// close remote connection
ssh2_exec($connection, 'exit');

Cheers.

Answer 2

Use phpseclib to securely SSH or SCP to remote servers

Install with composer require phpseclib/phpseclib

use phpseclib\Crypt\RSA;
use phpseclib\Net\SSH2;
use phpseclib\Net\SCP;

// Load your private key
$key = new RSA();
$key->loadKey('private key string');

// Connect to the server
$ssh = new SSH2('ip_address', 'port', 'timeout');
if (!$ssh->login('username', $key)) {
    throw new Exception("Unable to connect");
}

// Run a remote command
echo $ssh->exec('whoami');

// SCP put a string
$result = (new SCP($ssh))->put('remotePath', 'content to put');
// SCP put a file
$result = (new SCP($ssh))->put('remotePath', 'localPath', SCP::SOURCE_LOCAL_FILE);

// SCP get a file
$result = (new SCP($this->ssh))->get('remotePath', 'localPath');

// $result is true or false

Answer 3

Run SSH commands through PHP on server A to server B.

Here is how to run ssh commands with the command line in linux: http://www.youtube.com/watch?NR=1&feature=fvwp&v=YLqqdQZHzsU

In order to run commands on linux with PHP use the exec() command.

I hope this will get you started looking in the right direction.

Look at these two posts for automating the password prompt

• https://serverfault.com/questions/241588/how-to-automate-ssh-login-with-password
• https://serverfault.com/questions/187036/execute-ssh-command-without-password

Here is a quick example with non-working code to get you thinking:

<?php

    $server = "serverB.example.org";
    //ip address will work too i.e. 192.168.254.254 just make sure this is your public ip address not private as is the example

    //specify your username
    $username = "root";

    //select port to use for SSH
    $port = "22";

    //command that will be run on server B
    $command = "uptime";

    //form full command with ssh and command, you will need to use links above for auto authentication help
    $cmd_string = "ssh -p ".$port." ".$username."@".$server." ".$command;

    //this will run the above command on server A (localhost of the php file)
    exec($cmd_string, $output);

    //return the output to the browser
    //This will output the uptime for server B on page on server A
    echo '<pre>';
    print_r($output);
    echo '</pre>';
?>

The recommended flow is to run a command on server A to SSH to server B