Re: [Anima-bootstrap] Anima bootstrap: discover protocol multicast notes

[Brian E Carpenter <[e-mail]>]

Hi Toerless,

> (R)ight: L2 discovery protocol requirement:
> proxy needs to periodically (unsolicited) announce its proxy service via L2 multicast/broadcast
> pledge only accepts reply if it was multicast/broadcast
> pledge should then try to register via such discovered proxies.
> if multiple proxies discovered, parallel and/or sequential -> more difficult discussion

I take that as a vote for M_FLOOD

> The security of (R)ight depends on pledge being able to see if received packet from proxy was L2
> unicast or multicasted. 

Why? If a malicious node knows that pledges might be checking this, they will
multicast their bogus announcements. And how could they know the address of
a targetted pledge anyway, in order to send the bogus announcement unicast?

> This information is typically ignored in existing network protocol stacks
> and is also typically unavailable on the socket-API. This IMHO makes it highly beneficial to
> use a very lightweight protocol (like the subset of GRASP dedicate to this) that can specifically
> be implemented to do this security check.

Presumably you have to use a raw socket. I don't see any other way to get the
destination address out of the packet.

Regards
   Brian

On 18/01/2017 06:28, Toerless Eckert wrote:
> 
> Oh, and just read mDNS RFC and found the place where it prohibits
> periodic unsolicited announcements, so added that at the end.
> 
> Michael: Would be great if you
> can figure out what you see in your network. Worst case we'll have
> to ask Stewart...
> 
> Cheers
> Toerless
> 
> On Tue, Jan 17, 2017 at 06:17:32PM +0100, Toerless Eckert wrote:
>> Hi folks
>>
>> I have added my gist wrt to the discovery protocol detail i am
>> interested in to the etherpad
>>
>> http://etherpad.tools.ietf.org:9000/p/anima-boostrapping?useMonospaceFont=true
>>
>>  lines 368  - 407
>>
>> Hope this explains it better than my feeble verbal attempts during the call.
>>
>> Cheers
>> Toerless
>