nanog mailing list archives

RE: Using IPv6 with prefixes shorter than a /64 on a LAN


From: "George Bonser" <gbonser () seven com>
Date: Tue, 25 Jan 2011 10:49:51 -0800


So I pretty strongly disagree about your statement.  Repetitively
sweeping an IPv6 network to DoS/DDoS the ND protocol thereby
flooding
the ND cache/LRUs could be extremely effective and if not payed
serious attention will cause serious issues.



Yes.... This is an issue for point-to-point links but using a longer
prefix (/126 or similar) has been suggested as a mitigation for this
sort of attack.

I would assume that in the LAN scenario where you have a /64 for your
internal network that you would have some sort of stateful firewall
sitting infront of the network to stop any un-initiated sessions. This
therefore stops any hammering of ND cache etc. The argument then is
that
the number of packets hitting your firewall / bandwidth starvation
would
be the the alternative line of attack for a DoS/DDos but that is a
completely different issue.



So for /64 subnets used for point-to-points you disable ND, configure
static neighbors and that's the end of it. No ND DDoS.




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