[Dnsmasq-discuss] default lease time for dhcp-host entries ?
Maule Mark
mark_maule at yahoo.com
Tue Dec 17 17:27:23 GMT 2013
Thanks Simon. Will this work its way into a released version soon? If not, are there canned instructions for how to generate an srpm given a clone of the repo?
thanks
Mark
On Tuesday, December 17, 2013 10:32 AM, Simon Kelley <simon at thekelleys.org.uk> wrote:
On 16/12/13 21:37, Maule Mark wrote:
>> okay, thank you for checking.
>
>I just pushed a fix into git for the parsing bug.
>
>
>Cheers,
>
>Simon.
>
>
>>
>>
>>
>> On Monday, December 16, 2013 3:27 PM, Simon Kelley<simon at thekelleys.org.uk> wrote:
>>
>> On 16/12/13 21:00, Maule Mark wrote:
>>>> As an alternative to a fake tag to remove the empty field, would it work
>>>> to declare a static dhcp-range in my configuration file to cover the
>>>> addresses that are managed by the hostsfile?
>>>>
>>>
>>> No. As you'd expect, lease times configured for individual hosts
>>> override those in dhcp-ranges.
>>>
>>> I looked at the code, and it looks like the problem is indeed the double
>>> comma.
>>>
>>> ,,
>>>
>>> gets treated that same as
>>>
>>> ,0,
>>>
>>> ie a lease time of zero.
>>>
>>> That's a bug, but the easiest way for you to work around it is to avoid
>>> the double comma.
>>>
>>> Cheers,
>>>
>>> Simon.
>>>
>>>>
>>>> On Monday, December 16, 2013 2:47 PM, Maule Mark<mark_maule at yahoo.com>
>>>> wrote:
>>>>
>>>> I don't think our client is asking for a lease time. Or if it was,
>>>> I would also expect it to make the request on the very first
>>>> DHCPREQUEST, which gets the correct 1h lease.
>>>>
>>>> The double comma is to establish a placeholder field where we can
>>>> plug in an
optional tag: field, which we do in certain situations to
>>>> influence the next dhcp exchange for this id. The program we use to
>>>> manage this file rigidly expects each line to have the same number
>>>> of fields if this optional tag exists or not.. I'll try putting a
>>>> fake tag in that field and see if it solves the 2m lease time issue.
>>>>
>>>>
>>>>
>>>>
>>>> On Monday, December 16, 2013 2:28 PM, Simon Kelley
>>>> <simon at thekelleys.org.uk> wrote:
>>>>
>>>> On 16/12/13 19:36, Maule Mark wrote:
>>>> > I'm seeing an unexptected (to me) behavior when using a dnsmasq
>>>> > hostsfile and dhcp. To start, my interface (pmi_if) is
>>>> configured with
>>>> > a lease time of 1h (the default), and I have a blank hostsfile.
>>>> >
>>>> > dhcp-leasefile=/var/lib/axiom/dnsmasq_pmi.leases
>>>> >
dhcp-hostsfile=/var/lib/axiom/dnsmasq_pmi_hostsfile
>>>> > dhcp-range=172.30.80.0,static,255.255.255.0
>>>> > dhcp-range=172.30.80.200,172.30.80.240,255.255.255.0
>>>> > dhcp-lease-max=255
>>>> > dhcp-option=option:dns-server,172.30.80.1
>>>> > dhcp-option=option:router,172.30.80.1
>>>> > dhcp-option=option:ntp-server,172.30.80.1,172.30.80.2,172.30.80.3
>>>> > dhcp-option=option:default-ttl,50
>>>>
> dhcp-option=option:all-subnets-local,1
>>>> > dhcp-script=/var/lib/axiom/dhcp-script-pmi.sh
>>>> > dhcp-boot=/pds/pxe/pxelinux.0,172.30.80.1
>>>> >
>>>> > Clients boot and are assigned dhcp addresses as expected. We
>>>> have a
>>>> > program in our software stack that looks for heartbeat
>>>> messages on this
>>>> > pmi_if, and when detected, constructs a hostsfile
entry for
>>>> the client
>>>> > that looks like this:
>>>> >
>>>> > [root at pilot2<mailto:root at pilot2> axiom]# cat
>>>> dnsmasq_pmi_hostsfile
>>>> >
>>>> 00:21:28:A1:F3:F2,00:21:28:A1:F3:F3,,WN5080020001592690,172.30.80.128
>>>> >
>>>>
00:21:28:A1:CA:3A,00:21:28:A1:CA:3B,,WN5080020001592691,172.30.80.129
>>>> >
>>>> > The clients are running udhcpc from busybox.
>>>> >
>>>> > Everything works as expected until the clients get toward the
>>>> end of
>>>> > their 1h lease period at which point the clients start sending
>>>> > DHCPREQUEST requests. It seems at this point, that the
>>>> leases granted
>>>> > are now 120s. Here's some syslog output showing the first
>>>> DHCPREQUEST
>>>> > being sent about 55 minutes into the 1h initial lease. Why
>>>> did dnsmasq
>>>> > return a lease time of 12s in this case?
>>>> >
>>>> > 2013-12-16 19:33:42.253+00:00 pilot2 dnsmasq-dhcp[23916]:
>>>> 208328817
>>>> > DHCPREQUEST(pmi_if) 172.30.80.129
00:21:28:a1:ca:3a
>>>> > 2013-12-16 19:33:42.253+00:00 pilot2 dnsmasq-dhcp[23916]:
>>>> 208328817
>>>> > tags: known, pmi_if
>>>> > 2013-12-16 19:33:42.253+00:00 pilot2 dnsmasq-dhcp[23916]:
>>>> 208328817
>>>> > DHCPACK(pmi_if) 172.30.80.129 00:21:28:a1:ca:3a
>>>> WN5080020001592691
>>>> > 2013-12-16 19:33:42.253+00:00 pilot2 dnsmasq-dhcp[23916]:
>>>>
208328817
>>>> > requested options: 1:netmask, 3:router, 6:dns-server,
>>>> 12:hostname,
>>>> > 2013-12-16 19:33:42.253+00:00 pilot2 dnsmasq-dhcp[23916]:
>>>> 208328817
>>>> > requested options: 15:domain-name, 28:broadcast, 42:ntp-server
>>>> > 2013-12-16 19:33:42.253+00:00 pilot2 dnsmasq-dhcp[23916]:
>>>> 208328817
>>>> > bootfile name: /pds/pxe/pxelinux.0
>>>>
> 2013-12-16 19:33:42.253+00:00 pilot2 dnsmasq-dhcp[23916]:
>>>> 208328817
>>>> > server name: 172.30.80.1
>>>> > 2013-12-16 19:33:42.253+00:00 pilot2 dnsmasq-dhcp[23916]:
>>>> 208328817 next
>>>> > server: 172.30.80.3
>>>> > 2013-12-16 19:33:42.253+00:00 pilot2 dnsmasq-dhcp[23916]:
>>>> 208328817 sent
>>>> > size: 1 option: 53 message-type 5
>>>>
> 2013-12-16 19:33:42.253+00:00 pilot2 dnsmasq-dhcp[23916]:
>>>> 208328817 sent
>>>> > size: 4 option: 54 server-identifier 172.30.80.3
>>>> > 2013-12-16 19:33:42.253+00:00 pilot2 dnsmasq-dhcp[23916]:
>>>> 208328817 sent
>>>> > size: 4 option: 51 lease-time 2m
>>>> > 2013-12-16 19:33:42.253+00:00 pilot2 dnsmasq-dhcp[23916]:
>>>> 208328817 sent
>>>> >
size: 4 option: 58 T1 56s
>>>> > 2013-12-16 19:33:42.253+00:00 pilot2 dnsmasq-dhcp[23916]:
>>>> 208328817 sent
>>>> > size: 4 option: 59 T2 1m41s
>>>> > 2013-12-16 19:33:42.253+00:00 pilot2 dnsmasq-dhcp[23916]:
>>>> 208328817 sent
>>>> > size: 4 option: 1 netmask 255.255.255.0
>>>> > 2013-12-16 19:33:42.253+00:00 pilot2 dnsmasq-dhcp[23916]:
>>>> 208328817 sent
>>>> > size: 4 option: 28 broadcast 172.30.80.255
>>>> > 2013-12-16 19:33:42.253+00:00 pilot2 dnsmasq-dhcp[23916]:
>>>> 208328817 sent
>>>> > size: 5 option: 15 domain-name axiom
>>>> > 2013-12-16 19:33:42.253+00:00 pilot2 dnsmasq-dhcp[23916]:
>>>> 208328817 sent
>>>> > size: 18 option: 12 hostname WN5080020001592691
>>>> > 2013-12-16 19:33:42.253+00:00 pilot2
dnsmasq-dhcp[23916]:
>>>> 208328817 sent
>>>> > size: 20 option:209 70:78:65:6c:69:6e:75:78:2e:63:66:67:2f:64...
>>>> > 2013-12-16 19:33:42.253+00:00 pilot2 dnsmasq-dhcp[23916]:
>>>> 208328817 sent
>>>> > size: 4 option:208 f1:00:74:7e
>>>> > 2013-12-16 19:33:42.253+00:00 pilot2 dnsmasq-dhcp[23916]:
>>>> 208328817 sent
>>>> > size: 12 option: 42 ntp-server 172.30.80.1, 172.30.80.2,
>>>> 172.30.80.3
>>>> > 2013-12-16 19:33:42.253+00:00 pilot2 dnsmasq-dhcp[23916]:
>>>> 208328817 sent
>>>> > size: 4 option: 3 router 172.30.80.1
>>>> > 2013-12-16 19:33:42.253+00:00 pilot2 dnsmasq-dhcp[23916]:
>>>> 208328817 sent
>>>> > size: 4 option: 6 dns-server 172.30.80.1
>>>> >
>>>> >
>>>> > Is there a default lease time of 120s for client requests whose
>>>> > addresses which match a hoststfile entry?.
>>>>
>>>> No, there's no 120s default, but there is a 120s floor (ie no
>>>> lease less
>>>> the 120s will be issued).
>>>>
>>>> Note that the DHCP _client_ can ask for a particular lease time, it
>>>> would be interesting to see if it's sending a lease-time option
>>>> for 120s
>>>> or less in the DHCPREQUEST packet.
>>>>
>>>> Another potential issue is your hostfile:
>>>>
>>>> 00:21:28:A1:CA:3A,00:21:28:A1:CA:3B,,WN5080020001592691,172.30.80.129
>>>>
>>>> I've not looked, but the double comma may concievably confuse
>>>> the parser
>>>> such that it looks like a zero, which then gets interpreted as a
>>>> lease
>>>> time, and transformed to 120s by the floor.
>>>>
>>>> I think that is the most likely explanation.
>>>>
>>>> Cheers,
>>>>
>>>> Simon.
>>>>
>>>>
>>>> >
>>>> > thanks
>>>> > Mark
>>>>
>>>> >
>>>> >
>>>> >
>>>> >
_______________________________________________
>>>> > Dnsmasq-discuss mailing list
>>>> > Dnsmasq-discuss at lists.thekelleys.org.uk
>>>> <mailto:Dnsmasq-discuss at lists.thekelleys.org.uk>
>>>> > http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
>>>>
>
>>>>
>>>>
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>>>>
>>>>
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>>>
>>>
>>>
>>>
>
>
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>
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