On Wed, Dec 28, 2011 at 10:19 AM, Ray Soucy <rps@maine.edu> wrote:
There are a few solutions that vendors will hopefully look into. One being to implement neighbor discovery in hardware (at which point table exhaustion also becomes a legitimate concern, so the logic should be such that known associations are not discarded in favor of unknown associations).
Even if that is done you are still exposed to attacks -- imagine if a downstream machine that is under customer control (not yours) has a whole /64 nailed up on its Ethernet interface, and happily responds to ND solicits for every address. Your hardware table will fill up and then your network has failed -- which way it fails depends on the table eviction behavior. Perhaps this is not covered very well in my slides. There are design limits here that cannot be overcome by any current or foreseen technology. This is not only about what is broken about current routers but what will always be broken about them, in the absence of clever work-arounds like limits on the number of ND entries allowed per physical customer port, etc. We really need DHCPv6 snooping and ND disabled for campus access networks, for example. Otherwise you could give out addresses from a limited range in each subnet and use an ACL (like Owen DeLong suggests for hosting environments -- effectively turning the /64 into a /120 anyway) but this is IMO much worse than just not configuring a /64. On Wed, Dec 28, 2011 at 10:45 AM, <sthaug@nethelp.no> wrote:
I'm afraid I don't believe this is going to happen unless neighbor discovery based attacks become a serious problem. And even then it would take a long time.
The vendors seem to range from "huh?" to "what is everyone else doing?" to Cisco (the only vendor to make any forward progress at all on this issue.) I think that will change as this topic is discussed more and more on public mailing lists, and as things like DHCPv6 snooping, and good behavior when ND is disabled on a subnet/interface, begin to make their way into RFPs. As it stands right now, if you want to disable the IPv6 functionality (and maybe IPv4 too if dual-stacked) of almost any datacenter / hosting company offering v6, it is trivial to do that. The same is true of every IXP with a v6 subnet. I think once some bad guys figure this out, they will do us a favor and DoS some important things like IXPs, or a highly-visible ISP, and give the vendors a kick in the pants -- along with operators who still have the "/64 or bust" mentality, since they will then see things busting due to trivial attacks. -- Jeff S Wheeler <jsw@inconcepts.biz> Sr Network Operator / Innovative Network Concepts