Real-time SSH output with Net_SSH (phpseclib) - php

Question

I use Net_SSH (phpseclib) to execute SSH commands on an external server. I simply cannot figure out how to have real-time output from the command. I know how to make it run in the background so it's not dependant on the Apache process, but it's unclear how I'd go about showing the external output in real-time instead of having to wait for the command to finish.
My current code is as simple as $ssh->exec('command').
The PHP version used is:
[admin# ~]$ php -v
PHP 7.1.9 (cli) (built: Sep 10 2017 11:31:06) ( NTS )
Copyright (c) 1997-2017 The PHP Group
Zend Engine v3.1.0, Copyright (c) 1998-2017 Zend Technologies

Answer 1

I managed to get it working with libssh2 and output buffering, see example below:
$session = ssh2_connect("server.local", 22, array('hostkey'=> 'ssh-rsa' )) or die("Couldn't connect to the SSH Server.");
ssh2_auth_pubkey_file($session, "root", "/path/to/public/key.pub", "/path/to/private/key") or die("couldn't authenticate to server"); // Authenticating to the server with a ssh-key for security purposes
while (ob_end_flush()); // end all output buffers if any
$proc = ssh2_exec($session, "ping -c 40 google.nl");
echo '<pre class="scroll">';
echo "[root#server ~]# ping -c 5 google.nl\n"; // Command you will execute
while (!feof($proc))
{
echo fread($proc, 4096); // Read the output from the command
# flush(); // Flushes the whole php buffer so we can output new data
}
echo "\nDone";
echo '</pre>';
Don't forget that you need php 5.6 or lower for ssh2, you can replace the command in the variable $proc by $ssh->exec('command') as you use it.

Answer 2

I was able to get it working using this:
$ssh->exec('ping 127.0.0.1', function($output) {
echo $output;
});
To eliminate the variability in how your system is configured versus mine I'll use Vagrant to establish a common configuration. To that end, here's my Vagrantfile:
Vagrant.configure("2") do |config|
config.vm.box = "ubuntu/trusty64"
end
My full phpseclib code (using 1.0.7):
<?php
include('Net/SSH2.php');
$ssh = new Net_SSH2('127.0.0.1', 2222);
$ssh->login('vagrant', 'vagrant');
$ssh->exec('ping 127.0.0.1', function($output) {
echo $output;
});
A youtube video of the output:
https://youtu.be/j9-q3024eEk
If it's not working then several possibilities exist.
Maybe the "command" you're running simply doesn't dump output real time. Or maybe it requires a PTY or something. It's hard to comment since you haven't said what the command you're trying to run is. As my post demonstrates there are commands that my solution does work with.
Maybe it works with Vagrant but not with your system. Maybe your system has been configured in some funky way or something. In this scenario I guess what'd help is if you provided the SSH logs. You can get them by doing define('NET_SSH2_LOGGING', 2); and then echo $ssh->getLog();. Post the results in pastebin.com and then post the link.
edit: if you're running this in a webserver vs in the CLI you may encounter issues with how the webserver is setup - issues that go past phpseclib. For example, does this output real time or does it lock up?:
while (true) {
echo "test\n";
sleep(1);
}
flush() / ob_flush() might help but ultimately this would depend on the webserver you're using (Apache, nginx, etc), the SAPI you're using (CGI, Apache module, etc), etc.
I would consider this to be a "funky configuration".