Linux Ethernet Bridging - Apr 2007 - [Bridge] mac table updates

On Thu, 28 Jul 2005 16:23:43 -0700
Dirk Morris <dmorris@metaloft.com> wrote:
> I think the new mac ageing (sometime since 2.6.8.1) may be too
> aggressive. Now it updates the table at a much later time, with a
> comment in the code that leads me to believe
> this is to prevent counting spoofed packets and a DOS.
> 
> My problem is that the update occurs after the netfilter hooks which
> may do weird things to change the course of the packet so that it
> does not get counted.
> (in my case, redirecting, queueing to userspace, nonlocally bound 
> sockets, etc).
> For me this causes packets to go spewing out on the wrong interface
> when the timer expires.
> 
> I used the attached patch to revert back to the old method.
> 
> -Dirk
If you are whacking the source address, that seems wrong.  The fix for
that would be to copy the original source address somewhere, then
extract it back afterwards.

I think the new mac ageing (sometime since 2.6.8.1) may be too aggressive.
Now it updates the table at a much later time, with a comment in the 
code that leads me to believe
this is to prevent counting spoofed packets and a DOS.

My problem is that the update occurs after the netfilter hooks which may 
do weird things to change the course of the packet so that it does not 
get counted.
(in my case, redirecting, queueing to userspace, nonlocally bound 
sockets, etc).
For me this causes packets to go spewing out on the wrong interface when 
the timer expires.

I used the attached patch to revert back to the old method.

-Dirk
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