public function physAddresses() {
        $pa = $this->getSNMP()->walk1d(self::OID_IF_PHYS_ADDRESS);

        // some switches return leading '00:' as '0:' - we correct this here:
        foreach ($pa as $i => $a) {
            if (strpos($a, ':') == 1) {
                $pa[$i] = '0' . $a;
            }
        }

        return $pa;
    }