[OpenIndiana-discuss] How to configure a DUID for DHCPv6 usage?

[James Carlson]

On 04/15/16 08:46, Henner Gratz wrote:
> Thank you very much for your quick response. Because I'm no fan of endless
> debugging sessions, I've followed your second advice and got the source of
> dhcpagent and libdhcpagent. And after a first look at it I think that the
> code isn't able to parse a DUID of type 1 (and that's the only type DHCPv6
> supports for the identification of a client). The time in this DUID is only

What do you mean by "only type DHCPv6 supports?"

As far as the server is concerned, a DUID is just a bag of bits.  The
innards can be (and *should* be) treated as opaque by the server.  The
type number is there just for convenience of logging and display in
management tools.  If there's a server out there that's so broken that
it tries to "validate" the contents of a DUID and rejects certain types,
then my advice would be to start running -- fast -- in the opposite
direction.  Who knows what else is horribly broken?

See RFC 3315 section 9.  It clearly calls out that DUIDs are opaque, and
the only thing that makes sense with them is equality comparison.

> there to make it even less likely that two identical IDs exist. Once a DUID
> of type 1 is created it should be stored in a save place (OI/Solaris use
> /etc/dhcp/duid) and the time won't be changed again. So a DHCPv6 server is
> able to recognise a client - even after it has rebooted.

If I recall correctly, the constructed DUID is stored in stable storage
once created.  Look for the write_stable_duid() and read_stable_duid().
 They're in the dhcp_stable.c file in libdhcpagent.

Type 1 should work fine.  The user interface just provides no way to
specify the "time" portion of the DUID.  That is constructed
automatically.  You must specify "1,<hwaddr>,<hwaddress>", and dhcpagent
will add in the current time, and store the resulting DUID in a file
named /etc/dhcp/duid.

> And I think that there is a bug in the function get_smach_cid, because it's
> not even expected, that the string is DUID of type 1. The code just expects
> a DUID of type 3. But I hadn't much time to look at the source, I will take
> a closer look on the week-end. Hope this will result in a dhcpagent binary
> that also works for DHCPv6 clients with fixex addresses. Wish me luck...

I don't understand that response.

The code doesn't just "expect" a DUID of type 3.  What it does is parse
a string of the format "1,<hwtype>,<hwaddress>", and then it
automatically inserts the current time of day when it constructs the
type 1 DUID.

I'm pretty sure the only problem you had was setting the correct format
in the configuration file.

-- 
James Carlson         42.703N 71.076W         <carlsonj at workingcode.com>