Am 05.03.2020 um 13:27 schrieb Philip Homburg <pch-fbs...@u-1.phicoh.com>: > In your letter dated Wed, 4 Mar 2020 21:10:09 +0100 you wrote: >> This flag was introduced in a 2008 Security Advisory, because >> "non-neighbors" >> could abuse Neighbor Discovery to potentially cause denial-of-service >> situatio >> ns. >> In my situation it caused valid Neighbor Solicitation packets from my >> provider >> to be silently dropped, making the connection effectively unusable. > > In theory, the onlink status of a prefix should be announced in in > router advertisements and should be consistent across all nodes on a > subnet. In that sense, if this check fails then the network is misconfigured.
Good point, and probably an indication that my provider's setup is broken. But in terms of RFC-perspective, RAs and ND are not strictly related, I believe - for example, prefixes might have been configured manually (?). > That said, there is a specific check in processing Neighbor Discovery packets > that the hop limit is equal to 255. In that sense any node that manages to > send a packet with hop limit 255 is a neighbor, so I don't quite see how there > could be an attack by non-neighbors. Exactly, that's where I couldn't understand the Advisory. Though it seems to focus in router nodes, and not host nodes. - D. _______________________________________________ freebsd-net@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
