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List:       ipng
Subject:    Re: rfc3484-bis issue 2: privacy addresses
From:       Arifumi Matsumoto <arifumi () nttv6 ! net>
Date:       2011-06-29 5:28:18
Message-ID: 971D6F0B-9109-42EC-ABE0-1A5E3AB99741 () nttv6 ! net
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Hi Suresh,

On 2011/06/29, at 4:32, Suresh Krishnan wrote:

> Hi Tim,
> There is already a programmatic switch for this in RFC5014 \
> (IPV6_PREFER_SRC_TMP/IPV6_PREFER_SRC_PUBLIC). Applications wishing to override \
> system policy may do so by using this API.

Yes. An application can control which kind of address to choose by that API.

Our question is whether we should have a way to configure host-wide policy about when \
to use temporary address or not.

For example, if we extend the policy table to have Privacy column like below,

         Prefix        Precedence Label  Privacy
         ::1/128               60     0      OFF
         fc00::/7              50     1      OFF
         ::/0                  40     2       ON
         ::ffff:0:0/96         30     3      OFF
         2002::/16             20     4      OFF
         2001::/32             10     5      OFF
         ::/96                  1    10      OFF
         fec0::/10              1    11      OFF

a temporary address will be used only when a destination address longest matches ::/0 \
entry in this table.

Please note that this is about address selection and not about whether a host should \
generate temporary address for a received RA prefix.

As Tim mentioned, if we agree to have this kind of new tool, after that, we should \
discuss about policy distribution of this added column.

Best regards,

> 
> Cheers
> Suresh
> 
> ________________________________________
> From: ipv6-bounces@ietf.org [ipv6-bounces@ietf.org] On Behalf Of Tim Chown \
>                 [tjc@ecs.soton.ac.uk]
> Sent: Tuesday, June 28, 2011 10:38 AM
> To: ipv6@ietf.org
> Subject: rfc3484-bis issue 2: privacy addresses
> 
> The second issue is surrounding IPv6 privacy addresses (RFC4941).
> 
> Section 3.1 of RFC4941 states:
> "this document assumes that when a node initiates outgoing
> 
> communication, temporary addresses can be given preference over
> public addresses when the device is configured to do so.
> [ADDR_SELECT<http://tools.ietf.org/html/rfc4941#ref-ADDR_SELECT>] mandates \
> implementations to provide a mechanism, which allows an application to configure \
> its preference for temporary addresses over public addresses.  It also allows for \
> an implementation to prefer temporary addresses by default, so that the
> connections initiated by the node can use temporary addresses without
> requiring application-specific enablement."
> 
> 
> This suggests there should be a mechanism for a host to choose whether to use \
> temporary or public addresses.  RFC3484 talks about preferring temporary or public \
> addresses in Rule 7.  In practice, implementations seem to prefer privacy addresses \
> (to initiate connections) when they are enabled.  At the moment, RFC3484-bis says \
> nothing different or new for privacy addresses. 
> 
> Should there be a configuration switch for privacy extensions somewhere, and if so \
> how is this controlled - locally or via a policy distribution mechanism? 
> 
> In IETF80, the suggestion to 'tell' a host whether it should use privacy addresses \
> by using an RA flag was not well received. There was at least one comment at IETF80 \
> that the privilege to carry the traffic and the privilege to turn on/off the \
> privacy extension should be different. 
> 
> Comments please.
> 
> 
> Tim
> 
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--
Arifumi Matsumoto
  NGN System Architecture Project
  NTT Service Integration Laboratories
  E-mail: arifumi@nttv6.net
  TEL +81-422-59-3334 FAX +81-422-59-6364

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