// Created on savesnippets.com · https://savesnippets.com/vh8o9asXx4GoMP
<?php
function isPortOpen(string $host, int $port, float $timeoutSec = 2.0): bool {
    $fp = @fsockopen($host, $port, $errno, $errstr, $timeoutSec);
    if ($fp) { fclose($fp); return true; }
    return false;
}

var_dump(isPortOpen('google.com', 443));     // true
var_dump(isPortOpen('google.com', 12345));   // false
var_dump(isPortOpen('localhost', 3306));     // true if MySQL is running locally