Re: draft-ietf-6man-slaac-renum: Heuristics to deprecate stale information

[Michael Richardson <[e-mail]>]

Ted Lemon <[e-mail]> wrote:
    > RS, they seem low-cost. I am somewhat concerned that a cleverly-timed
    > attack while a router is known to be down could result in bogus
    > prefixes being preferred on the link until the router comes back, and
    > that this could break connections on the link that would otherwise
    > survive. But this seems like a fairly useless denial-of-service attack.

If I understand the attack you are thinking about,  it would depend on the
addresses expiring from the nodes while the router is down and can not renew
the prefix lifetimes.

The attacker deprecates the addresses, by impersonating the router, and
nodes kill connections.    One answer, I think, is that any existing sockets
that are using those addresses can just continue to use them.
New connections/sockets would not use those addresses.

I know that my browsers all seem to notice when there is an address change
and they restart connections.  I'm not entirely sure if this is just based
upon opening the routing socket and listening, or if there is a lower
overhead mechanism... I'd sure like to be able to toggle a socket option on a
bind()/connect()'ed socket (both TCP and UDP) to get an error if the
addresses involved go into deprecated state.

The sockets might actually break if they are connections to the Internet, but
they would break anyway in that case.  If they are just across the link, then
they would just continue working.


--
Michael Richardson <[e-mail]>   . o O ( IPv6 IøT consulting )
           Sandelman Software Works Inc, Ottawa and Worldwide