DHCID calculation bug

René GARCIA rene.garcia at sogeti.com
Tue Jul 21 12:44:56 UTC 2009

Le vendredi 17 juillet 2009 18:55 de la part de David W. Hankins
> I think the RFC approach is to require that clients implement the
DUID-based client 
> identifier, in which case the DHCPv6 and DHCPv4 client on the same system
would be
> identified by the same DUID.  The specification is a little incomplete
because it
> doesn't alter the non- normative direction in RFC 2131 requiring a server
to treat
> the DHCPv4 client identifier as an opaque value, but this is not normative
so a
> server that does this still conforms.

Yes, I agree. Therefore the RFC4703 (5.2.  Dual IPv4/IPv6 Client
Considerations) describes how a dual stack client has to perform DHCP
requests using the same DUID for both IPv4 and IPv6 requests.

In current source code DHCID RDATA is calculated from DUID only when a
lease6 is involved, this means that DUID from a DHCPv4 client is ignored. In
the other hand I don't know if there is any working DHCP IPv4 client sending
the DUID information in its requests as described in rfc4361. I can spend
some time on building a patch for ISC DHCPD but I need a rfc4361 compliant
DHCP IPv4 client.

I guess that sending DUID option in DHCP requests in IPv4 shoud be the new
standard but even the brand new Windows Seven does not send it. This will
not help the IPv4/IPv6 transition.


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