php - ssh2_exec failed allocating pty - php

Question

Using PHP, I need to periodically execute a remote command on a Draytek 2925 router using SSH.
I can already connect to the router using the standard "ssh" command on Linux, but after authenticating I am getting "PTY allocation request failed on channel 0". However despite that message, I can still send commands.
When I try doing the same with PHP, I am getting 1 of 2 results and neither of which is returning the results I need.
My code is as follows:
<?
if (!($connection = ssh2_connect('my.router.local', 22)))
die('CONN');
else if (!ssh2_auth_password($connection, 'admin', 'password'))
die('AUTH');
else
{
$stream = ssh2_exec($connection, 'sys version');
stream_set_blocking($stream, true);
$stream_out = ssh2_fetch_stream($stream, SSH2_STREAM_STDIO);
echo stream_get_contents($stream_out);
exit();
}
?>
The PHP fails at ssh2_exec(). If I specify the 3rd argument (pty), I get this result:
Warning: ssh2_exec(): Failed allocating 1 pty at 80x25 characters
However, not specifying the 3rd argument results in:
Warning: ssh2_exec(): Unable to request command execution on remote host
Even if I type #ssh2_exec(), I don't get a warning, but I don't get a result either.
If PHP is a no-go, I tried using sshpass in the same way, but that results in the following:
# sshpass -f sshpwd -v ssh admin#my.router.local 'sys version'
SSHPASS searching for password prompt using match "assword"
SSHPASS read: admin#my.router.local's password:
SSHPASS detected prompt. Sending password.
SSHPASS read:
exec request failed on channel 0
#
I ultimately just need to authenticate, send a command and return the result. Is there anything I am doing wrong or is there a simpler way?

Answer 1

I have resolved my query by using TELNET instead. Yes it's not secure like SSH, but since it's being used internally over the LAN, it doesn't matter.
For anyone interested, I used Net_Telnet and the following code:
<?php
require_once "Net/Telnet.php";
$router = 'my.router.local';
$password = 'password';
try
{
$t = new Net_Telnet($router);
$t->connect();
$t->login([
'login_prompt' => 'Account:',
'login_success' => ' User login successful, expired time is "Unlimited".',
'login_fail' => '% Access denied',
'login' => 'admin',
'password' => $password,
'prompt' => "{$router}>",
]
);
echo $t->cmd('sys version');
$t->disconnect();
// catch any buffered data
echo $t->get_data();
echo "\n";
} catch (Exception $e)
{
echo "Caught Exception ('{$e->getMessage()}')\n{$e}\n";
}
exit();
?>
Which results in:
# php -f telnet.php
sys version
Router Model: Vigor2925n Version: 3.8.4 English
Profile version: 3.0.0 Status: 1 (0x48245e4c)
Router IP: 0.0.0.0 Netmask: 255.255.255.0
Firmware Build Date/Time: Dec 15 2016 17:26:01
Router Name: my.router.local
Revision: 61327 V384_2925
>
#