[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Re: Debian installer dhcp problems



On Thu, 29 Sep 2011 13:39:06 -0600, Bob Proulx wrote:

> Camaleón wrote:
>> Niklas Jakobsson wrote:
>> > I found this post to the dhcp-users mailing list:
>> > https://lists.isc.org/pipermail/dhcp-users/2011-July/013440.html
>> 
>> W-o-w... that's incredible.
>> So it is not working even in the upstream dhcpd? :-o
> 
> It may be unintuitive but ignoring client identifier is incorrect. That
> is why patching to do so isn't accepted upstream.  Ignoring client
> identifier violates the protocol.  See RFC 2131.

Yes, I guess that's what man page also warns about, so what's the point 
in adding a setting that in the end cannot be honored? :-?

***
The duplicates flag tells the DHCP server that if a request is received
from a client that matches the MAC address of a host  declaration,  any
other  leases  matching  that  MAC  address  should be discarded by the
server, even if the UID is not the same.   This is a violation  of  the
DHCP  protocol, but can prevent clients whose client identifiers change
regularly from holding many leases  at  the  same  time.   By  default,
duplicates are allowed.
***

I mean, the patch is aimed to solve something that is currently there but 
is not working or did I miss something?

> Now that doesn't mean that in restricted cases it isn't beneficial to
> violate some protocols.  I violate protocols!  (I want that tshirt by
> the way.  :-) 

Maybe at "thinkgeek.com"? ;-)

> Expecially when it suits me.  But it does prevent it from
> being general purpose and certainly should not be the default.

If I read the man page correctly, it certainly is not the default but the 
option is available for specific sitations.

> A typical suggestion for people provisioning a large number of systems
> would be to identify PXE clients using vendor-class-identifier and
> assign those a short lease time so that those addresses expire quickly
> to keep from depleting the pool.

I agree there has to be a better/another way to get the job done.
 
>> > It adds a new option ignore-client-uids to dhcpd. I applied the patch
>> > and recompiled my dhcp-server and it works exactly as intended.
>> > 
>> > So, my problem is solved...
>> 
>> Good to know, and thanks for posting the above URI and confirming the
>> patch works. What scares me is to see no replies to the user who posted
>> the message on the dhcpd mailing list...
> 
> Search for Yedidyah Bar-David (aka Didi) single lease dhcp patch and you
> should get to various discussions going back several years.  This isn't
> a new topic.  It comes up periodically concerning booting multiple
> different operating systems and having each system assigned its own
> address.

Hum... I was not aware this was part of that well-know-discussed issues, 
but regardless its "awareness status", is something that should addressed 
at dhcp mailing list. I think is a valid concern for users and they 
deserve a proper response, whatever it be.

Greetings,

-- 
Camaleón


Reply to: