Simple way to check if player is using Waterdog proxy to connect to PMMP server

waterdog-address.php

<?php

use pocketmine\event\Listener;
use pocketmine\event\server\DataPacketReceiveEvent;
use pocketmine\network\mcpe\protocol\LoginPacket;

class ProxyCheck implements Listener {

    /**
     * List of addresses that may bypass this restriction
     * Include address of Waterdog too (usually 0.0.0.0 if running on same node)
     * @var array
     */
    public $acceptedIPs = ["0.0.0.0", "127.0.0.1"];

    /**
     * @param DataPacketReceiveEvent $event
     */
    public function onPacketReceive(DataPacketReceiveEvent $event): void {
        if(!($event->getPacket() instanceof LoginPacket)) return;
        /** @var LoginPacket $packet */
        $packet = $event->getPacket();

        $player = $event->getPlayer();
        $remoteAddress = $packet->clientData["WaterDog_RemoteIP"] ?? null;

        if ($remoteAddress === null || !in_array($player->getAddress(), $this->acceptedIPs, true)){
            //Player is not joined over Waterdog Proxy or his address is not accepted
            return;
        }

        try {
            //Set right address to player class
            $class = new ReflectionClass($player);
            $prop = $class->getProperty("ip");
            $prop->setAccessible(true);
            $prop->setValue($player, $remoteAddress);
        }catch (Exception $e){
            //ignore
        }
    }
}