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Today's Topics:

   1. one-lease-per-client... seriously (Brian Rak)
   2. Re: one-lease-per-client... seriously (Jeff Wieland)
   3. Re: one-lease-per-client... seriously (Simon Hobson)


----------------------------------------------------------------------

Message: 1
Date: Thu, 15 Sep 2016 16:00:14 -0400
From: Brian Rak <b...@gameservers.com>
To: dhcp-users@lists.isc.org
Subject: one-lease-per-client... seriously
Message-ID: <dcf10ee2-1a93-8ba8-6b8f-442a0e783...@gameservers.com>
Content-Type: text/plain; charset=utf-8; format=flowed

I'm running into an issue where DHCPD (v4.3.4 and older versions) is 
issuing multiple leases to the same mac address.  It appears to be 
looking at the DHCP Client-ID field to determine what a unique client 
is.  I'd much rather it ignore everything except for the client's mac 
address, but I can't seem to find an option to do this.

I already have:

one-lease-per-client                                    true;
deny duplicates;

in my config, which doesn't seem to be helping.

This is a problem, because I'm using DHCP for PXE booting, which means 
each machine ends up getting three concurrent leases:

one via the firmware built into the nic
iPXE then gets chainloaded, and gets another lease
the actual OS gets loaded, and gets a different lease

It's very difficult to get these all to share leases, and I'd really 
much rather handle this on the DHCP server side.  DNSMasq can do this, 
but it doesn't scale well enough.



------------------------------

Message: 2
Date: Thu, 15 Sep 2016 16:33:15 -0400
From: Jeff Wieland <wiel...@purdue.edu>
To: Users of ISC DHCP <dhcp-users@lists.isc.org>
Subject: Re: one-lease-per-client... seriously
Message-ID: <57db058b.2010...@purdue.edu>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Brian Rak wrote:
> I'm running into an issue where DHCPD (v4.3.4 and older versions) is 
> issuing multiple leases to the same mac address.  It appears to be 
> looking at the DHCP Client-ID field to determine what a unique client 
> is.  I'd much rather it ignore everything except for the client's mac 
> address, but I can't seem to find an option to do this.
>
> I already have:
>
> one-lease-per-client                                    true;
> deny duplicates;
>
> in my config, which doesn't seem to be helping.
>
> This is a problem, because I'm using DHCP for PXE booting, which means 
> each machine ends up getting three concurrent leases:
>
> one via the firmware built into the nic
> iPXE then gets chainloaded, and gets another lease
> the actual OS gets loaded, and gets a different lease
>
> It's very difficult to get these all to share leases, and I'd really 
> much rather handle this on the DHCP server side.  DNSMasq can do this, 
> but it doesn't scale well enough.
>
> _______________________________________________
> dhcp-users mailing list
> dhcp-users@lists.isc.org
> https://lists.isc.org/mailman/listinfo/dhcp-users
>
I've not used it, but it looks like the ignore-client-uids statement 
might work.

--
Jeff Wieland, UNIX/Network Systems Administrator
Purdue University IT Infrastructure Services UNIX Platforms



------------------------------

Message: 3
Date: Fri, 16 Sep 2016 08:00:15 +0100
From: Simon Hobson <dh...@thehobsons.co.uk>
To: Users of ISC DHCP <dhcp-users@lists.isc.org>
Subject: Re: one-lease-per-client... seriously
Message-ID: <bd617e57-bd4d-4ce2-a1db-70a7c2e6e...@thehobsons.co.uk>
Content-Type: text/plain; charset=us-ascii


On 15 Sep 2016, at 21:00, Brian Rak <b...@gameservers.com> wrote:

> I'm running into an issue where DHCPD (v4.3.4 and older versions) is issuing 
> multiple leases to the same mac address.  It appears to be looking at the 
> DHCP Client-ID field to determine what a unique client is.

That is by design as is **REQUIRED** by the RFCs.
It's a long standing problem that some real-world situations clash with this - 
most notably when there is multi-boot with Windoze and anything else since 
Windows defaults to using the MAC address as client-id and everything else 
defaults to not sending one. But that's what the standards require and the ISC 
implementation has always been intended to be a "reference" implementation that 
completely meets the standards as laid down (unlike several other servers which 
really do break the rules a lot).

>  I'd much rather it ignore everything except for the client's mac address, 
> but I can't seem to find an option to do this.

It used to require patches, but I see Jeff has suggested an option to deal with 
this.



------------------------------

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