Fred correctly points out that this text from draft-ietf-ipv6-privacy-
addrs-v2-0.txt is inaccurate:
2.4 Possible Approaches
One way to avoid having a static non-changing address is to use
DHCPv6 [DHCPV6] for obtaining addresses. The DHCPv6 server could be
configured to hand out addresses that change over time. But DHCPv6
will solve the privacy issue only if it frequently handed out
constantly changing addresses to the nodes or if the DHCPv6 client
moves from links to links frequently, being allocated independent
addresses from different DHCPv6 servers. However, the former does
not happen automatically, and is difficult to configure manually;
the
latter cannot be assumed for static (not frequently moving) hosts.
Thus, DHCPv6 is not a self contained alternative for solving the
privacy issues addressed by this document. However, in the absence
of stateless address autoconfiguration, DHCPv6 can be used for
distributing temporary addresses to clients.
DHCPv6 explicitly includes the IA_TA (IA for temporary addresses)
construct which provides for RFC 3041 addressing; see section 12 of
RFC 3315:
12. Management of Temporary Addresses
A client may request the assignment of temporary addresses (see RFC
3041 [12] for the definition of temporary addresses). DHCPv6
handling of address assignment is no different for temporary
addresses. DHCPv6 says nothing about details of temporary addresses
like lifetimes, how clients use temporary addresses, rules for
generating successive temporary addresses, etc.
Clients ask for temporary addresses and servers assign them.
Temporary addresses are carried in the Identity Association for
Temporary Addresses (IA_TA) option (see section 22.5). Each IA_TA
option contains at most one temporary address for each of the
prefixes on the link to which the client is attached.
The IAID number space for the IA_TA option IAID number space is
separate from the IA_NA option IAID number space.
The server MAY update the DNS for a temporary address, as described
in section 4 of RFC 3041.
Fred, thanks for your careful read and analysis of RFC 3315.
- Ralph
On Aug 18, 2006, at 12:45 PM, Templin, Fred L wrote:
Suresh,
[http://www.ietf.org/internet-drafts/draft-ietf-ipv6-privacy-addrs-
v2-04
.txt]
This draft seems to link itself unnecessarily with Stateless
Address Autoconfiguration, since it seems that the same
mechanisms work under DHCPv6 - see: (RFC3315, Section 22.5).
Unless I am missing something, the only difference I see is
that the entity that generates the temporary addresses is
the DHCP server instead of the client.
In particular, the text of Section 2.4, paragraph 1 beginning:
"But DHCPv6 will solve the privacy issue" is new since RFC3041
and seems to make questionable statements about the use of DHCP
for generating temporary addresses, since 1) the server can be
configured to hand out temporary addresses with short preferred/
valid lifetimes, and 2) the client can go back to the server to
get new temporary addresses whenever it wants to regardless of
preferred/valid lifetimes.
Again, unless I am missing something, suggestions are to
1) remove this new text from Section 2.4, and 2) relax any
text (including the document title) that links the generation
of privacy addresses with Stateless Address Autoconfiguration.
Fred
[EMAIL PROTECTED]
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