DHCPv6 and MAC Address inclusion

[perl-list]

BTW: we are running isc dhcp 4.2.3p1 

I assume the ia-na .... from the leases file is similar to the UID from DHCPv4 leases file: 

uid client-identifier; 

The uid statement records the client identifier used by the client to acquire the lease. Clients are not required to send client identifiers, and this statement only appears if the client did in fact send one. Client identifiers are normally an 
ARP type (1 for ethernet) followed by the MAC address, just like in the hardware statement, but this is not required. 

The client identifier is recorded as a colon-separated hexadecimal list or as a quoted string. If it is recorded as a quoted string and it contains one or more non-printable characters, those characters are represented as octal escapes - a back- 
slash character followed by three octal digits. 

----- Original Message -----

> From: "perl-list" <perl-list at network1.net>
> To: "Users of ISC DHCP" <dhcp-users at lists.isc.org>
> Sent: Wednesday, January 25, 2012 3:35:21 PM
> Subject: Re: DHCPv6 and MAC Address inclusion

> It SEEMS like the windows machine is using the MAC although I am not
> sure of DUID vs IAID and where each can be seen.

> I just disabled / enabled adapter on test windows7 laptop here ... I
> have some numbers available (sans packet capture) from logs and from
> the leases file (dhcpd ):

> 00:15:c5:14:ce:b0 (the actual mac of the windows computer)
> dhcpd: Client 00:01:00:01:13:e0:fd:f1: 00:15:c5:14:ce:b0 releases
> address 2620:0:2e50:e8:1::f541 (line from the log file - I assume
> that is DUID - seems to contain full mac)
> ia-na
> "\305\025\000\020\000\001\000\001\023\340\375\361\000\025\305\024\316\260"
> (Opener to the lease entry in leases file - i have no idea what that
> string of stuff is)

> ----- Original Message -----

> > From: "Michael Dean Pugh" <mdpugh at hotmail.com>
> 
> > To: dhcp-users at isc.org
> 
> > Sent: Wednesday, January 25, 2012 3:00:05 PM
> 
> > Subject: Re: DHCPv6 and MAC Address inclusion
> 

> > I'm jumping in at the end here and not responding to any particular
> > post. I
> 
> > have followed this thread with great interest. This seems like a
> > good
> > time to
> 
> > make an observation and ask a question.
> 

> > There is much talk about deriving the MAC address from IPv6
> > identifiers.
> 
> > While it's true that in most cases (every case I've personally
> > observed--
> 
> > Windows and FreeBSD) the MAC is part of the DUID, this is only
> > useful
> > if the
> 
> > host has one interface as the DUID is unique to the host not the
> > interface (I
> 
> > think we're all in agreement here). Also, once the host has
> > assigned
> > itself
> 
> > the DUID, the interface can be replaced, but the DUID will remain
> > the
> > same, so
> 
> > the MAC address derived from the DUID at this point would be
> > invalid.
> > Again,
> 
> > this is with Windows and FreeBSD.
> 

> > Now, the observation. Microsoft encodes the first 24 bits of the
> > MAC
> > address
> 
> > (the manufacturer portion) in the IAID by directly copying them
> > into
> > the last
> 
> > 24 bits of the IAID. In other words, if the MAC is
> > 01:23:45:ab:cd:ef,
> > the
> 
> > IAID is xy012345(Hex) for some x and y. This has limited usefulness
> > since it
> 
> > is entirely possible to have more than one interface from the same
> 
> > manufacturer installed in one host (it seems like it would have
> > made
> > more
> 
> > sense to have used the last 24 bits of the MAC).
> 

> > This brings me to the question. Does anyone know how the first 8
> > bits
> > of the
> 
> > IAID are derived by Microsoft? I'm pretty sure I found this
> > somewhere
> > on the
> 
> > Internet, but have been unable to find it again. I'm also wondering
> > if
> 
> > Microsoft's IAID algorithm is based on any standards or if the IAID
> > is merely
> 
> > a 32-bit number. It does seem that the IAID holds enough
> > information
> > to
> 
> > uniquely identify each interface on a single managed network.
> 

> > _______________________________________________
> 
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> 
> > dhcp-users at lists.isc.org
> 
> > https://lists.isc.org/mailman/listinfo/dhcp-users
> 

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