Aerys\Host::separateIPv4Binding PHP Method

    public static function separateIPv4Binding() : bool
    {
        static $separateIPv6 = null;
        if ($separateIPv6 === null) {
            // PHP 7.0.0 doesn't have ipv6_v6only socket option yet
            if (PHP_VERSION_ID < 70001) {
                $separateIPv6 = !file_exists("/proc/sys/net/ipv6/bindv6only") || trim(file_get_contents("/proc/sys/net/ipv6/bindv6only"));
            } else {
                $separateIPv6 = true;
            }
        }
        return $separateIPv6;
    }