North American Network Operators Group
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Re: key change for TCP-MD5

  • From: Iljitsch van Beijnum
  • Date: Fri Jun 23 19:19:24 2006 
On 24-jun-2006, at 0:43, Owen DeLong wrote:
Why couldn't the network device do an AH check in hardware before passing
the
packet to the receive path? If you can get to a point where all connections
or traffic TO the router should be AH, then, that will help with DOS.
If you care that much, why don't you just add an extra loopback address, give it an RFC 1918 address, have your peer talk BGP towards that address and filter all packets towards the actual interface address of the router?

The chance of an attacker sending an RFC 1918 packet that ends up at your router is close to zero and even though the interface address still shows up in traceroutes etc it is bullet proof because of the filters.

(This works even better with IPv6 link local addresses, those are guaranteed to be unroutable.)