Logging questions

Tim Gavin livewire98801 at gmail.com
Thu Mar 18 17:25:33 UTC 2010

So Opt82 isn't included in the DHCPDISCOVER log entry?

On Thu, Mar 18, 2010 at 09:56, Marc Perea <marccp at srttel.com> wrote:
> Tim,
> option 82 info is pretty easy to log to syslog, provided you always hand
> back a lease. Something like this in the dhcpd.conf:
> if exists agent.circuit-id {
>         log(info,concat(binary-to-ascii(10,8,".",leased-address)," ASSIGNED
> TO AGENT.CIRCUIT-ID => ",option agent.circuit-id));
> }
> will produce output like:
> Mar 17 11:29:26 isg-dhcp dhcpd: [ID 702911 daemon.info] DHCPOFFER on
> 74.207.x.y to 00:1a:2b:54:a9:e2 via
> Mar 17 11:29:26 isg-dhcp dhcpd: [ID 702911 daemon.info] 74.207.x.y ASSIGNED
> BUT, be aware that in a no free leases situation, no offer will be made
> (which is what generates the logging above), and you will simply get this
> instead:
> Mar 17 11:28:24 isg-dhcp dhcpd: [ID 702911 daemon.error] DHCPDISCOVER from
> 00:40:36:22:5a:c0 via network isg-test: no free leases
> Note there is no option 82 info on where your error is coming from. For us,
> this means one of our hundreds of relay agents has this customer MAC
> attached to it that is unable to get a lease, but which one?
> This patch claims to fix that, but I haven't tried it (yet):
> http://www.miquels.cistron.nl/isc-dhcpd/patch-server::02-log-agent-options
> As for question 2, I haven't really thought about that situation much and
> haven't had to troubleshoot by L2 address nearly as often as L3, so haven't
> found as much of a need for formatting it appropriately. Anyone else have
> any thoughts?
> HTH,
> --Marc
> Message: 4
> Date: Wed, 17 Mar 2010 11:34:49 -0700
> From: Tim Gavin <livewire98801 at gmail.com>
> Subject: Logging questions
> To: Users of ISC DHCP <dhcp-users at lists.isc.org>
> Message-ID:
> <10af9a9a1003171134l47b66ed9jaeb567a6d2d6b7a4 at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
> I have two questions pertaining to logging.  I've looked through the
> archives, but can't make sense of the responses.  I think it's because
> everyone's trying to do more with it than I want to do.
> First question:
> I'm about to start getting option 82 information from our layer two
> vendor network (I admin a ISP fiber network), and it appears that
> people have issues getting that info logged into the syslog.  Is this
> something I have to add, or is it only when people use fancy logging
> scripts that this is an issue?  If it's something I have to add,
> what's the easiest way to do it?
> Second (less critical) question:
> The MACs are logged in "computer standard" format of
> aa:bb:cc:dd:ee:ff.  This is all well and good normally, but all of my
> equipment, and all of our vendor's equipment is Cisco. That means I
> have to reformat every MAC when flipping back and forth between
> routers/switches and the DHCP server.  Is there any way I can change
> the logging format to aabb.ccdd.eeff ?
> Thanks :)
> Tim
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