Preconditions for accepting address update events

[boaks]

Security and Privacy Considerations

The part

When a record with CID is received that has the source address of the enclosing
UDP datagram different from the one previously associated with that CID, the
receiver MUST NOT update its view of the peer’s address with the source
specified in the UDP packet before cryptographically validating the enclosed
record(s). This is to ensure that a man-on-the-side attacker that sends a
packet with a different source address on an existing CID session does not
successfully manage to reroute any return traffic.

of PR #65 didn't made to the draft, or did I miss it?

In the meantime, I would even go further:
Applying MAC and Anti-Replay may validates the record cryptographically, and so the receive windows may be updated and the application data may be forwarded. But, if the epoch/sequence_number is not newer than the newest successfully validate epoch/sequence_number before, the address update event itself may be wrong! Assuming, that a address-change is located somewhere on the message's route, it seems to be not possible to distinguish, if the message was delayed after the "address change" (and so that address is deprecated) or before that (and so the address would be the new one). If that could not be decided, I would go for updating the address only for newer records.
Using that approach, updating the address only for newer records (based on epoch/sequence_number) with validated MAC, would also mitigate the first two attacks of issue #64, though retransmitting an record with changed address will not update the address, because these records are NOT newer.

[hannestschofenig]

I have updated the text of #70 and was wondering whether it captures your issue. I am not sure what steps I have to take to meet your requirements.

[boaks]

As long as RFC6347, 4.1.2.6 - anti replay doesn't get mandatory (MUST), everything for me will be OK.

So, yes, PR #70 addresses it in the right way.

[thomas-fossati]

It looks like #70 closes this issue?

[boaks]

Thanks!