Ian Grigg wrote:
Bill Stewart wrote:
Also, the author's document discusses protecting BGP to prevent
some of the recent denial-of-service attacks,
and asks for confirmation about the assertion in a message
on the IPSEC mailing list suggesting
"E.g., it is not feasible for BGP routers to be configured with the
appropriate certificate authorities of hundreds of thousands of peers".
Routers typically use BGP to peer with a small number of partners,
though some big ISP gateway routers might peer with a few hundred.
(A typical enterprise router would have 2-3 peers if it does BGP.)
If a router wants to learn full internet routes from its peers,
it might learn 1-200,000, but that's not the number of direct connections
that it has - it's information it learns using those connections.
And the peers don't have to be configured "rapidly without external assistance" -
you typically set up the peering link when you're setting up the
connection between an ISP and a customer or a pair of ISPs,
and if you want to use a CA mechanism to certify X.509 certs,
you can set up that information at the same time.
On the backbone, between BGP peers, one would have thought that there are relatively few attackers, as the staff are highly trusted and the wires are hard to access - hence no active attacks going on and only some passive eavesdropping attacks. Also, anyone setting up BGP routing knows the other party, so there is a prior relationship.
My understanding of the attacks this past spring is that: a) they were indeed on the backbone BGP peers b) that those peers had avoided setting up preshared keys or getting mutually-authenticatable certificates because of the configuration overhead (small on a per-pair basis, but may be large in aggregate)
While inspired by this issue, there may be other solutions (e.g., IMO IPsec) which are more appropriate for BGP peers.
The whole point of the CA model is that there is no prior relationship and that the network is a wild wild west sort of place
Except that certs need to be signed by authorities that are trusted.
- both of these assumptions seem to be reversed in the backbone world, no? So one would think that using opportunistic cryptography would be ideal for the BGP world?
iang
I wouldn't think that the encryption need be opportunistic; in the BGP backbone world, as you noted, peers are known a-priori, and should have certs that could be signed by well-known, trusted CAs.
Joe
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