tcp md5 bgp attacks?

Randy Bush randy at psg.com
Wed Aug 15 02:27:28 UTC 2018


my memory is that seq num guessing and sending rst was the core problem
motivating tcp/md5 for bgp, and btsh came some years later.  but no big
deal.

i think that, indeed, md5 keys are shared across many links *within* an
op's infrastructure.  but, since integrity, and not privacy, is the
goal, this does not seem risky.  carrying keys to new networks seems a
bit risky as does re-use with multiple external parties.

> given the existance of effective mitigations for the ibgp case, I've
> need seen a reason to employ it internally or to explore support for
> rfc 4808 mechnisms since key rolling is effectively an external
> coordination problem.

if i need to roll keys on ibgp, i suspect i have a far more serious
problem than if it is ebgp, twice as serious at a minimum :)

< rathole >
i am not much worried about a mesh which floods unicast.  can you even
buy devices which support that any more?  a while back, i had to really
dig in the closet to find one at 100mbps so i could shark mid-stream.

> I have thousands of establish connections that last a very long time
> at public exchange points, so the threat of tcp rsts to sessions is
> clearly not being realized.

my theory is that, as the attacks were mitigated the attackers moved on
to other things.  after all, the non-nuisance benefit i get by resetting
your bgp session with margaret is shifting your traffic past some place
i can mitm or to a more expensive, to you, link.  the attackers moved on
to more lucrative endeavors.

randy


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