Re: rfc4941bis: temporary addresses as "outgoing-only"?

Brian E Carpenter <brian.e.carpenter@gmail.com> Tue, 11 February 2020 21:07 UTC

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Subject: Re: rfc4941bis: temporary addresses as "outgoing-only"?
To: Fernando Gont <fgont@si6networks.com>, Mark Smith <markzzzsmith@gmail.com>
Cc: 6MAN <6man@ietf.org>
References: <3217323b-3d8b-bf75-b5b0-ffdd01ee1501@si6networks.com> <CAO42Z2xtvjo_RO7kNsFCi4=S0TJKRest-8fEkvnwbC3rBNAj0A@mail.gmail.com> <ac38ca41-a148-470a-d2ba-26649f77e2f8@gmail.com> <992cb8c9-f360-44f1-89fe-ec9b1abd0846@si6networks.com>
From: Brian E Carpenter <brian.e.carpenter@gmail.com>
Message-ID: <8f88c95f-dc13-5d42-bbc1-1839f6ce8433@gmail.com>
Date: Wed, 12 Feb 2020 10:07:47 +1300
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On 11-Feb-20 16:44, Fernando Gont wrote:
> On 10/2/20 19:17, Brian E Carpenter wrote:
>> On 11-Feb-20 09:46, Mark Smith wrote:
>>>
>>>
>>> On Tue, 11 Feb 2020, 03:13 Fernando Gont, <fgont@si6networks.com <mailto:fgont@si6networks.com>> wrote:
>>>
>>>      Folks,
>>>
>>>      Since we are at it, I wonder if rfc4941bis should say anything about the
>>>      use of temporary addresses for incoming connections. (see
>>>      https://tools.ietf.org/html/draft-gont-6man-address-usage-recommendations-04#section-4.3).
>>>      (e.g., "an implementation MAY....")
>>>
>>>      Particularly for connection-oriented protocols, hosts that prevent
>>>      incoming connections on temporary addresses reduce exposure even when
>>>      their temporary addresses become "exposed" by outgoing sessions.
>>>
>>>      i.e., if the model is that temporary addresses are employed for outgoing
>>>      connections, unless a host uses temporary-only, there's no reason to
>>>      receive incoming connections on temporary addresses. (e.g., browsing the
>>>      web or sending email should not be an invitation for folks to e.g.
>>>      port-scan you).
>>>
>>>
>>> This would prevent peer-to-peer connections between end-user devices, as it means devices become clients only, and they therefore cannot provide a temporary server/service.
>>
>> If a node has a stable address as well as a temporary address, that isn't the case. 
> 
> That's what I had in mind.
> 
> 
>> However, I think it is rather out of scope for 6man to regulate this point. What might be good, but is also probably out of scope,
>> is a socket option to allow/disallow incoming connections to temp addresses, and a socket error code if they are disallowed and an upper layer tries to bind a socket to a temp address.
> 
> The thing here is that, unless the address has been generated upon 
> request of an app (something not possible at the time of this writing), 
> apps share addresses and thus no app has authority over any address...

Technically, yes, but if the socket option required root privilege it could OK. Anyway it's part of a broader problem, not part of 4941bis, IMHO.

    Brian