[Bridge] linux bridge does not bridge bpdu packets

Roman Glebov sleon at sleon.dyndns.org
Mon Apr 23 06:52:14 PDT 2007

when i disable all lines in net/bridge/br.c which are related to following

static struct llc_sap *br_stp_sap;
        br_stp_sap = llc_sap_open(LLC_SAP_BSPAN, br_stp_rcv);
        if (!br_stp_sap) {
                printk(KERN_ERR "bridge: can't register sap for STP\n");
                return -EADDRINUSE;

Will i get as result that all stp packets are passed untouched other the
bridge ?

With regards,
Roman Glebov

>> Roman Glebov wrote:
>>> Hallo,
>>> i have here transparent linux based bridge.
>>> The problem is : all stp packets which come to one side of the Bridge
>>> are
>>> not forwarded to the other side. Which distrubs stp when this device is
>>> put inbetween of two stp capable devices.
>>> It forwards all traffik through it.
>>> Normal udp/tcp traffik is forwarded.
>>> I switched stp on it "off" so it does not participate in Spanning tree
>>> communications.
>>> It is a very simple setup :
>>> br0 with eth0 and eht1 as ports. without any additional firewall rules.
>>> I am using 2.6.18-4-686 debian kernel(testing).
>>> i even did setfd br0 0.
>>> What am i doing wrong ?
>>> Do i need to use ebtables to explicitely forward the traffic?
>> Turn on STP in the bridge, it will then receive process and send it's
>> own STP BPDU's.
> this makes my "stealth" bridge not stealphy anymore!
> because you can see in bptu packets its mac.
> That is what i want to prevent.
> I want it to be completely transparent and not seen in the network
> traffic.
> So should i patch the kernel for it ?
> Roman Glebov
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