Re: [babel] Comments about rfc7298bis

[Juliusz Chroboczek <[e-mail]>]

Thanks for the explanation, that helps.  I'm going to read 7183 when
I have time.

> Do you see any ways for this to go wrong?

Probably not, but I'm not quite comfortable yet.  Please be patient,
I probably get the details wrong in the following example.

Suppose that Chloe has captured a large number of packets previously sent
by alice.  Alice left the network, and state relevant to Alice has expired
at Bob.

Now Alice joins the network, and sends

  A: Hello, TS/PC = 42

Now Chloe sends a replayed packet:

  C (spoofing A): Update (::/0, 0), TS/PC = 43

Bob sees this as a route announcement from Alice, so he inserts a default
route in its route table.  Since Alice hasn't sent an IHU yet, the link
cost is infinite, so the route doesn't get installed.

Bob sends a Hello:

  B: Hello, TS/PC = 57

and Alice sends an IHU with the correct TS/PC echo:

  A: IHU(TS/PC=57), TS/PC = 43

the IHU gets ignored, due to the obsolete TS/PC (43), but then Alice
resends the IHU:

  A: IHU(TS/PC=57), TS/PC = 44

This packet is correct, so BOB sets its txcost to something finite, and
bang, the route suddenly is selectable, and Bob installs the route that
was spoofed by Chloe.

What am I missing?

-- Juliusz