protected function checkConnectionsPerIp($connection)
    {
        $ip = $connection->getIp();

        if (!$ip) {
            $this->logger->warning('Cannot check connections per IP');
            return;
        }

        if (!isset($this->ips[$ip])) {
            $this->ips[$ip] = 1;
        } else {
            $this->ips[$ip] = min(
                $this->options['connections_per_ip'],
                $this->ips[$ip] + 1
            );
        }

        if ($this->ips[$ip] > $this->options['connections_per_ip']) {
            $this->limit($connection, 'Connections per IP');
        }
    }