Groups > linux.debian.user > #201544 > unrolled thread

strange DHCP behaviour

Started by	Tony van der Hoff <tony@vanderhoff.org>
First post	2018-10-23 16:20 +0200
Last post	2018-10-24 17:00 +0200
Articles	20 on this page of 25 — 10 participants

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  strange DHCP behaviour Tony van der Hoff <tony@vanderhoff.org> - 2018-10-23 16:20 +0200
    Re: strange DHCP behaviour Roberto C. Sánchez <roberto@debian.org> - 2018-10-23 16:30 +0200
      Re: strange DHCP behaviour tony <lists@vanderhoff.org> - 2018-10-23 18:10 +0200
    Re: strange DHCP behaviour Martin <keine-eile@online.de> - 2018-10-23 17:20 +0200
      Re: strange DHCP behaviour tony <lists@vanderhoff.org> - 2018-10-23 18:00 +0200
      Re: strange DHCP behaviour john doe <johndoe65534@mail.com> - 2018-10-23 18:40 +0200
        Re: strange DHCP behaviour john doe <johndoe65534@mail.com> - 2018-10-23 19:50 +0200
          Re: strange DHCP behaviour john doe <johndoe65534@mail.com> - 2018-10-23 20:10 +0200
            Re: strange DHCP behaviour tony <lists@vanderhoff.org> - 2018-10-24 10:40 +0200
        Re: strange DHCP behaviour tony <lists@vanderhoff.org> - 2018-10-23 19:50 +0200
    Re: strange DHCP behaviour mick crane <mick.crane@gmail.com> - 2018-10-23 21:10 +0200
      Re: strange DHCP behaviour tony <lists@vanderhoff.org> - 2018-10-24 10:50 +0200
        Re: strange DHCP behaviour mick crane <mick.crane@gmail.com> - 2018-10-24 12:20 +0200
          Re: strange DHCP behaviour tony <lists@vanderhoff.org> - 2018-10-24 12:40 +0200
            Re: strange DHCP behaviour mick crane <mick.crane@gmail.com> - 2018-10-24 13:00 +0200
              Re: strange DHCP behaviour tony <lists@vanderhoff.org> - 2018-10-24 13:20 +0200
    Re: strange DHCP behaviour deloptes <deloptes@gmail.com> - 2018-10-23 22:00 +0200
      Re: strange DHCP behaviour tony <lists@vanderhoff.org> - 2018-10-24 11:00 +0200
    Re: strange DHCP behaviour Reco <recoverym4n@enotuniq.net> - 2018-10-24 08:30 +0200
      Re: strange DHCP behaviour tony <lists@vanderhoff.org> - 2018-10-24 13:30 +0200
        Re: strange DHCP behaviour john doe <johndoe65534@mail.com> - 2018-10-24 13:40 +0200
          Re: strange DHCP behaviour [SOLVED] tony <lists@vanderhoff.org> - 2018-10-24 14:40 +0200
            Re: strange DHCP behaviour [SOLVED] <tomas@tuxteam.de> - 2018-10-24 14:50 +0200
              Re: strange DHCP behaviour [SOLVED] tony <lists@vanderhoff.org> - 2018-10-25 14:50 +0200
            Re: strange DHCP behaviour [SOLVED] Michael Stone <mstone@debian.org> - 2018-10-24 17:00 +0200

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#201544 — strange DHCP behaviour

From	Tony van der Hoff <tony@vanderhoff.org>
Date	2018-10-23 16:20 +0200
Subject	strange DHCP behaviour
Message-ID	<wM5Hj-6JR-11@gated-at.bofh.it>

Hi, I havea laptop running fully up to date Stretch with NetworkManager,
set to use DH|Cp via wireless.

The DHCP server is another Stretch system, with the stanzas
host tony-lt {
	hardware ethernet 0c:60:76:6c:e6:6f;
	fixed-address 192.168.1.199;
	}
subnet 192.168.1.0 netmask 255.255.255.0
	{
        range 192.168.1.200 192.168.1.254;
        option routers 192.168.1.10;
	}

That MAC is correct for the laptop.

I an expecting to see 192.168.1.199 as the laptop address, but no, if a
gives:
wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP
group default qlen 1000
    link/ether 0c:60:76:6c:e6:6f brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.253/24 brd 192.168.1.255 scope global dynamic wlan0
       valid_lft 479sec preferred_lft 479sec

Finally, the server shows:
Oct 23 14:23:38 routerpi dhcpd[1068]: DHCPREQUEST for 192.168.1.253 from
0c:60:76:6c:e6:6f (tony-lt) via eth0
Oct 23 14:23:38 routerpi dhcpd[1068]: DHCPACK on 192.168.1.253 to
0c:60:76:6c:e6:6f (tony-lt) via eth0
Oct 23 14:23:53 routerpi dhcpd[1068]: reuse_lease: lease age 15 (secs)
under 25% threshold, reply with unaltered, existing lease for 192.168.1.253
Oct 23 14:23:53 routerpi dhcpd[1068]: DHCPREQUEST for 192.168.1.253 from
0c:60:76:6c:e6:6f (tony-lt) via eth0
Oct 23 14:23:53 routerpi dhcpd[1068]: DHCPACK on 192.168.1.253 to
0c:60:76:6c:e6:6f (tony-lt) via eth0

So, my question: why is the server handing out .253, when it is
configured to provide .199?
What is this 'reuse-lease' all about?

I've tried 'dhclient -r wlan 0; dhclient -v wlan0' on the laptop, to no
avail.

Any suggestions, please?
-- 
Tony van der Hoff  | mailto:tony@vanderhoff.org
Ariège, France     |

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#201545

From	Roberto C. Sánchez <roberto@debian.org>
Date	2018-10-23 16:30 +0200
Message-ID	<wM5QZ-6MV-11@gated-at.bofh.it>
In reply to	#201544

On Tue, Oct 23, 2018 at 03:56:34PM +0200, Tony van der Hoff wrote:
> 
> So, my question: why is the server handing out .253, when it is
> configured to provide .199?
> What is this 'reuse-lease' all about?
> 
> I've tried 'dhclient -r wlan 0; dhclient -v wlan0' on the laptop, to no
> avail.
> 
> Any suggestions, please?

You don't provide the entirety of your configuration file, so this is a
stab in the dark, but do you have a stanza that occurs earlier in the
file that is matching the host in question?

Regards,

-Roberto
-- 
Roberto C. Sánchez

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#201556

From	tony <lists@vanderhoff.org>
Date	2018-10-23 18:10 +0200
Message-ID	<wM7pM-7NH-15@gated-at.bofh.it>
In reply to	#201545

On 23/10/2018 16:22, Roberto C. Sánchez wrote:
> On Tue, Oct 23, 2018 at 03:56:34PM +0200, Tony van der Hoff wrote:
>>
>> So, my question: why is the server handing out .253, when it is
>> configured to provide .199?
>> What is this 'reuse-lease' all about?
>>
>> I've tried 'dhclient -r wlan 0; dhclient -v wlan0' on the laptop, to no
>> avail.
>>
>> Any suggestions, please?
> 
> You don't provide the entirety of your configuration file, so this is a
> stab in the dark, but do you have a stanza that occurs earlier in the
> file that is matching the host in question?
> 
> Regards,
> 
> -Roberto
> 
Thanks for your suggestion, Roberto; in fact I did provide the entire
config, at least the part that's not commented out. so, no, there are no
other stanzas.

Cheers, Tony

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#201551

From	Martin <keine-eile@online.de>
Date	2018-10-23 17:20 +0200
Message-ID	<wM6Do-7iy-27@gated-at.bofh.it>
In reply to	#201544

Shouldn't the host definition be inside the subnet definition?

Am 23.10.18 um 15:56 schrieb Tony van der Hoff:
> Hi, I havea laptop running fully up to date Stretch with NetworkManager,
> set to use DH|Cp via wireless.
> 
> The DHCP server is another Stretch system, with the stanzas
> host tony-lt {
> 	hardware ethernet 0c:60:76:6c:e6:6f;
> 	fixed-address 192.168.1.199;
> 	}
> subnet 192.168.1.0 netmask 255.255.255.0
> 	{
>         range 192.168.1.200 192.168.1.254;
>         option routers 192.168.1.10;
> 	}
> 
> That MAC is correct for the laptop.
> 
> I an expecting to see 192.168.1.199 as the laptop address, but no, if a
> gives:
> wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP
> group default qlen 1000
>     link/ether 0c:60:76:6c:e6:6f brd ff:ff:ff:ff:ff:ff
>     inet 192.168.1.253/24 brd 192.168.1.255 scope global dynamic wlan0
>        valid_lft 479sec preferred_lft 479sec
> 
> Finally, the server shows:
> Oct 23 14:23:38 routerpi dhcpd[1068]: DHCPREQUEST for 192.168.1.253 from
> 0c:60:76:6c:e6:6f (tony-lt) via eth0
> Oct 23 14:23:38 routerpi dhcpd[1068]: DHCPACK on 192.168.1.253 to
> 0c:60:76:6c:e6:6f (tony-lt) via eth0
> Oct 23 14:23:53 routerpi dhcpd[1068]: reuse_lease: lease age 15 (secs)
> under 25% threshold, reply with unaltered, existing lease for 192.168.1.253
> Oct 23 14:23:53 routerpi dhcpd[1068]: DHCPREQUEST for 192.168.1.253 from
> 0c:60:76:6c:e6:6f (tony-lt) via eth0
> Oct 23 14:23:53 routerpi dhcpd[1068]: DHCPACK on 192.168.1.253 to
> 0c:60:76:6c:e6:6f (tony-lt) via eth0
> 
> So, my question: why is the server handing out .253, when it is
> configured to provide .199?
> What is this 'reuse-lease' all about?
> 
> I've tried 'dhclient -r wlan 0; dhclient -v wlan0' on the laptop, to no
> avail.
> 
> Any suggestions, please?
>

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#201553

From	tony <lists@vanderhoff.org>
Date	2018-10-23 18:00 +0200
Message-ID	<wM7g6-7vg-9@gated-at.bofh.it>
In reply to	#201551

On 23/10/2018 17:14, Martin wrote:
> Shouldn't the host definition be inside the subnet definition?

Thanks for the suggestion, Martin. The sample config file supplied with
the DHCP package shows a host outside the subnet. Anyway, I tried it,
and it made no difference.

Thanks anyway.

Cheers, Tony

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#201559

From	john doe <johndoe65534@mail.com>
Date	2018-10-23 18:40 +0200
Message-ID	<wM7SO-7Xl-19@gated-at.bofh.it>
In reply to	#201551

On 10/23/2018 5:14 PM, Martin wrote:
> Shouldn't the host definition be inside the subnet definition?
> 
> Am 23.10.18 um 15:56 schrieb Tony van der Hoff:
>> Hi, I havea laptop running fully up to date Stretch with NetworkManager,
>> set to use DH|Cp via wireless.
>>
>> The DHCP server is another Stretch system, with the stanzas
>> host tony-lt {
>> 	hardware ethernet 0c:60:76:6c:e6:6f;
>> 	fixed-address 192.168.1.199;
>> 	}
>> subnet 192.168.1.0 netmask 255.255.255.0
>> 	{
>>         range 192.168.1.200 192.168.1.254;
>>         option routers 192.168.1.10;
>> 	}
>>

maybe settingthe the subnet definition before the host definition could
help.
In '/var/lib/dhcpd/dhcpd.leases' removing the lease for the host in
question could be worth a try.

https://linux.die.net/man/5/dhcpd.leases

-- 
John Doe

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#201563

From	john doe <johndoe65534@mail.com>
Date	2018-10-23 19:50 +0200
Message-ID	<wM8Yy-8i-7@gated-at.bofh.it>
In reply to	#201559

On 10/23/2018 7:39 PM, tony wrote:
> On 23/10/2018 18:36, john doe wrote:
>> On 10/23/2018 5:14 PM, Martin wrote:
>>> Shouldn't the host definition be inside the subnet definition?
>>>
>>> Am 23.10.18 um 15:56 schrieb Tony van der Hoff:
>>>> Hi, I havea laptop running fully up to date Stretch with NetworkManager,
>>>> set to use DH|Cp via wireless.
>>>>
>>>> The DHCP server is another Stretch system, with the stanzas
>>>> host tony-lt {
>>>> 	hardware ethernet 0c:60:76:6c:e6:6f;
>>>> 	fixed-address 192.168.1.199;
>>>> 	}
>>>> subnet 192.168.1.0 netmask 255.255.255.0
>>>> 	{
>>>>         range 192.168.1.200 192.168.1.254;
>>>>         option routers 192.168.1.10;
>>>> 	}
>>>>
>>
>> maybe settingthe the subnet definition before the host definition could
>> help.
>> In '/var/lib/dhcpd/dhcpd.leases' removing the lease for the host in
>> question could be worth a try.
>>
>> https://linux.die.net/man/5/dhcpd.leases
>>
> thanks, John; I tried both those suggestions, to nil effect. It still
> insists on grabbing ..253 for itself.
> 
> Cheers, Tony
> 

Can you give us your all dhcpd.conf file?

-- 
John Doe

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#201566

From	john doe <johndoe65534@mail.com>
Date	2018-10-23 20:10 +0200
Message-ID	<wM9hT-tQ-1@gated-at.bofh.it>
In reply to	#201563

On 10/23/2018 7:49 PM, john doe wrote:
> On 10/23/2018 7:39 PM, tony wrote:
>> On 23/10/2018 18:36, john doe wrote:
>>> On 10/23/2018 5:14 PM, Martin wrote:
>>>> Shouldn't the host definition be inside the subnet definition?
>>>>
>>>> Am 23.10.18 um 15:56 schrieb Tony van der Hoff:
>>>>> Hi, I havea laptop running fully up to date Stretch with NetworkManager,
>>>>> set to use DH|Cp via wireless.
>>>>>
>>>>> The DHCP server is another Stretch system, with the stanzas
>>>>> host tony-lt {
>>>>> 	hardware ethernet 0c:60:76:6c:e6:6f;
>>>>> 	fixed-address 192.168.1.199;
>>>>> 	}
>>>>> subnet 192.168.1.0 netmask 255.255.255.0
>>>>> 	{
>>>>>         range 192.168.1.200 192.168.1.254;
>>>>>         option routers 192.168.1.10;
>>>>> 	}
>>>>>
>>>
>>> maybe settingthe the subnet definition before the host definition could
>>> help.
>>> In '/var/lib/dhcpd/dhcpd.leases' removing the lease for the host in
>>> question could be worth a try.
>>>
>>> https://linux.die.net/man/5/dhcpd.leases
>>>
>> thanks, John; I tried both those suggestions, to nil effect. It still
>> insists on grabbing ..253 for itself.
>>
>> Cheers, Tony
>>
> 
> Can you give us your all dhcpd.conf file?
> 

I would rather ask for help at:

https://lists.isc.org/mailman/listinfo/dhcp-users

-- 
John Doe

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#201576

From	tony <lists@vanderhoff.org>
Date	2018-10-24 10:40 +0200
Message-ID	<wMmRQ-8uE-21@gated-at.bofh.it>
In reply to	#201566

On 23/10/2018 20:06, john doe wrote:
> On 10/23/2018 7:49 PM, john doe wrote:
>> On 10/23/2018 7:39 PM, tony wrote:
>>> On 23/10/2018 18:36, john doe wrote:
>>>> On 10/23/2018 5:14 PM, Martin wrote:
>>>>> Shouldn't the host definition be inside the subnet definition?
>>>>>
>>>>> Am 23.10.18 um 15:56 schrieb Tony van der Hoff:
>>>>>> Hi, I havea laptop running fully up to date Stretch with NetworkManager,
>>>>>> set to use DH|Cp via wireless.
>>>>>>
>>>>>> The DHCP server is another Stretch system, with the stanzas
>>>>>> host tony-lt {
>>>>>> 	hardware ethernet 0c:60:76:6c:e6:6f;
>>>>>> 	fixed-address 192.168.1.199;
>>>>>> 	}
>>>>>> subnet 192.168.1.0 netmask 255.255.255.0
>>>>>> 	{
>>>>>>         range 192.168.1.200 192.168.1.254;
>>>>>>         option routers 192.168.1.10;
>>>>>> 	}
>>>>>>
>>>>
>>>> maybe settingthe the subnet definition before the host definition could
>>>> help.
>>>> In '/var/lib/dhcpd/dhcpd.leases' removing the lease for the host in
>>>> question could be worth a try.
>>>>
>>>> https://linux.die.net/man/5/dhcpd.leases
>>>>
>>> thanks, John; I tried both those suggestions, to nil effect. It still
>>> insists on grabbing ..253 for itself.
>>>
>>> Cheers, Tony
>>>
>>
>> Can you give us your all dhcpd.conf file?
>>
> 
> I would rather ask for help at:
> 
> https://lists.isc.org/mailman/listinfo/dhcp-users
> 

Yes, that'll be my next port of call. Thanks.
Cheers, Tony

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#201564

From	tony <lists@vanderhoff.org>
Date	2018-10-23 19:50 +0200
Message-ID	<wM8Yy-8i-9@gated-at.bofh.it>
In reply to	#201559

On 23/10/2018 18:36, john doe wrote:
> On 10/23/2018 5:14 PM, Martin wrote:
>> Shouldn't the host definition be inside the subnet definition?
>>
>> Am 23.10.18 um 15:56 schrieb Tony van der Hoff:
>>> Hi, I havea laptop running fully up to date Stretch with NetworkManager,
>>> set to use DH|Cp via wireless.
>>>
>>> The DHCP server is another Stretch system, with the stanzas
>>> host tony-lt {
>>> 	hardware ethernet 0c:60:76:6c:e6:6f;
>>> 	fixed-address 192.168.1.199;
>>> 	}
>>> subnet 192.168.1.0 netmask 255.255.255.0
>>> 	{
>>>         range 192.168.1.200 192.168.1.254;
>>>         option routers 192.168.1.10;
>>> 	}
>>>
> 
> maybe settingthe the subnet definition before the host definition could
> help.
> In '/var/lib/dhcpd/dhcpd.leases' removing the lease for the host in
> question could be worth a try.
> 
> https://linux.die.net/man/5/dhcpd.leases
> 
thanks, John; I tried both those suggestions, to nil effect. It still
insists on grabbing ..253 for itself.

Cheers, Tony

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#201568

From	mick crane <mick.crane@gmail.com>
Date	2018-10-23 21:10 +0200
Message-ID	<wMadX-124-1@gated-at.bofh.it>
In reply to	#201544

On 2018-10-23 14:56, Tony van der Hoff wrote:
> Hi, I havea laptop running fully up to date Stretch with 
> NetworkManager,
> set to use DH|Cp via wireless.
> 
> The DHCP server is another Stretch system, with the stanzas
> host tony-lt {
> 	hardware ethernet 0c:60:76:6c:e6:6f;
> 	fixed-address 192.168.1.199;
> 	}
> subnet 192.168.1.0 netmask 255.255.255.0
> 	{
>         range 192.168.1.200 192.168.1.254;
>         option routers 192.168.1.10;
> 	}
> 
> That MAC is correct for the laptop.
> 
> I an expecting to see 192.168.1.199 as the laptop address, but no, if a
> gives:
> wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP
> group default qlen 1000
>     link/ether 0c:60:76:6c:e6:6f brd ff:ff:ff:ff:ff:ff
>     inet 192.168.1.253/24 brd 192.168.1.255 scope global dynamic wlan0
>        valid_lft 479sec preferred_lft 479sec
> 
> Finally, the server shows:
> Oct 23 14:23:38 routerpi dhcpd[1068]: DHCPREQUEST for 192.168.1.253 
> from
> 0c:60:76:6c:e6:6f (tony-lt) via eth0
> Oct 23 14:23:38 routerpi dhcpd[1068]: DHCPACK on 192.168.1.253 to
> 0c:60:76:6c:e6:6f (tony-lt) via eth0
> Oct 23 14:23:53 routerpi dhcpd[1068]: reuse_lease: lease age 15 (secs)
> under 25% threshold, reply with unaltered, existing lease for 
> 192.168.1.253
> Oct 23 14:23:53 routerpi dhcpd[1068]: DHCPREQUEST for 192.168.1.253 
> from
> 0c:60:76:6c:e6:6f (tony-lt) via eth0
> Oct 23 14:23:53 routerpi dhcpd[1068]: DHCPACK on 192.168.1.253 to
> 0c:60:76:6c:e6:6f (tony-lt) via eth0
> 
> So, my question: why is the server handing out .253, when it is
> configured to provide .199?
> What is this 'reuse-lease' all about?
> 
> I've tried 'dhclient -r wlan 0; dhclient -v wlan0' on the laptop, to no
> avail.
> 
> Any suggestions, please?

bearing in mind that I've no idea what I'm talking about is it possible 
that the laptop connected to the server and got a really long lease on 
.253 before you added

host tony-lt {
hardware ethernet 0c:60:76:6c:e6:6f;
  	fixed-address 192.168.1.199;
  	}
probably there is a command to flush leases ?

mick



-- 
Key ID    4BFEBB31

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#201577

From	tony <lists@vanderhoff.org>
Date	2018-10-24 10:50 +0200
Message-ID	<wMn1w-6n-1@gated-at.bofh.it>
In reply to	#201568

On 23/10/2018 21:03, mick crane wrote:
> On 2018-10-23 14:56, Tony van der Hoff wrote:
>> Hi, I havea laptop running fully up to date Stretch with NetworkManager,
>> set to use DH|Cp via wireless.
>>
>> The DHCP server is another Stretch system, with the stanzas
>> host tony-lt {
>>     hardware ethernet 0c:60:76:6c:e6:6f;
>>     fixed-address 192.168.1.199;
>>     }
>> subnet 192.168.1.0 netmask 255.255.255.0
>>     {
>>         range 192.168.1.200 192.168.1.254;
>>         option routers 192.168.1.10;
>>     }
>>
>> That MAC is correct for the laptop.
>>
>> I an expecting to see 192.168.1.199 as the laptop address, but no, if a
>> gives:
>> wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP
>> group default qlen 1000
>>     link/ether 0c:60:76:6c:e6:6f brd ff:ff:ff:ff:ff:ff
>>     inet 192.168.1.253/24 brd 192.168.1.255 scope global dynamic wlan0
>>        valid_lft 479sec preferred_lft 479sec
>>
>> Finally, the server shows:
>> Oct 23 14:23:38 routerpi dhcpd[1068]: DHCPREQUEST for 192.168.1.253 from
>> 0c:60:76:6c:e6:6f (tony-lt) via eth0
>> Oct 23 14:23:38 routerpi dhcpd[1068]: DHCPACK on 192.168.1.253 to
>> 0c:60:76:6c:e6:6f (tony-lt) via eth0
>> Oct 23 14:23:53 routerpi dhcpd[1068]: reuse_lease: lease age 15 (secs)
>> under 25% threshold, reply with unaltered, existing lease for
>> 192.168.1.253
>> Oct 23 14:23:53 routerpi dhcpd[1068]: DHCPREQUEST for 192.168.1.253 from
>> 0c:60:76:6c:e6:6f (tony-lt) via eth0
>> Oct 23 14:23:53 routerpi dhcpd[1068]: DHCPACK on 192.168.1.253 to
>> 0c:60:76:6c:e6:6f (tony-lt) via eth0
>>
>> So, my question: why is the server handing out .253, when it is
>> configured to provide .199?
>> What is this 'reuse-lease' all about?
>>
>> I've tried 'dhclient -r wlan 0; dhclient -v wlan0' on the laptop, to no
>> avail.
>>
>> Any suggestions, please?
> 
> bearing in mind that I've no idea what I'm talking about is it possible
> that the laptop connected to the server and got a really long lease on
> .253 before you added
> 
> host tony-lt {
> hardware ethernet 0c:60:76:6c:e6:6f;
>      fixed-address 192.168.1.199;
>      }
> probably there is a command to flush leases ?
> 
I've flushed the lease several times (The dhclient -r command mentioned
above does that), and physically deleted the lease files.  No good!

Cheers, Tony

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#201579

From	mick crane <mick.crane@gmail.com>
Date	2018-10-24 12:20 +0200
Message-ID	<wMoqB-12T-3@gated-at.bofh.it>
In reply to	#201577

On 2018-10-24 09:40, tony wrote:

> I've flushed the lease several times (The dhclient -r command mentioned
> above does that), and physically deleted the lease files.  No good!
> 

Isn't that on the laptop and you need to get rid of the entry on the 
server ?

mick


-- 
Key ID    4BFEBB31

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#201580

From	tony <lists@vanderhoff.org>
Date	2018-10-24 12:40 +0200
Message-ID	<wMoJX-195-1@gated-at.bofh.it>
In reply to	#201579

On 24/10/2018 12:11, mick crane wrote:
> On 2018-10-24 09:40, tony wrote:
> 
>> I've flushed the lease several times (The dhclient -r command mentioned
>> above does that), and physically deleted the lease files.  No good!
>>
> 
> Isn't that on the laptop and you need to get rid of the entry on the
> server ?
> 
> mick
> 
> 
Well, it's the client that's requesting it; the server's just complying.

Cheers, Tony

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#201582

From	mick crane <mick.crane@gmail.com>
Date	2018-10-24 13:00 +0200
Message-ID	<wMp3j-1fI-1@gated-at.bofh.it>
In reply to	#201580

On 2018-10-24 11:39, tony wrote:
> On 24/10/2018 12:11, mick crane wrote:
>> On 2018-10-24 09:40, tony wrote:
>> 
>>> I've flushed the lease several times (The dhclient -r command 
>>> mentioned
>>> above does that), and physically deleted the lease files.  No good!
>>> 
>> 
>> Isn't that on the laptop and you need to get rid of the entry on the
>> server ?
>> 
>> mick
>> 
>> 
> Well, it's the client that's requesting it; the server's just 
> complying.
> 

why would client request a fixed ipaddress from dhcp server ?
sure it's the server you need to flush.
I could have a look on mine to see how in terminal but I want to make 
some sausage rolls.

mick

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#201583

From	tony <lists@vanderhoff.org>
Date	2018-10-24 13:20 +0200
Message-ID	<wMpmF-1Bd-7@gated-at.bofh.it>
In reply to	#201582

On 24/10/2018 12:54, mick crane wrote:
> On 2018-10-24 11:39, tony wrote:
>> On 24/10/2018 12:11, mick crane wrote:
>>> On 2018-10-24 09:40, tony wrote:
>>>
>>>> I've flushed the lease several times (The dhclient -r command mentioned
>>>> above does that), and physically deleted the lease files.  No good!
>>>>
>>>
>>> Isn't that on the laptop and you need to get rid of the entry on the
>>> server ?
>>>
>>> mick
>>>
>>>
>> Well, it's the client that's requesting it; the server's just complying.
>>
> 
> why would client request a fixed ipaddress from dhcp server ?
> sure it's the server you need to flush.
> I could have a look on mine to see how in terminal but I want to make
> some sausage rolls.
> 

I have no idea, but it complies with the documentation. The client
should request a renewal of its existing lease, which the server will
acknowledge with DHCPACK if OK or a DHCPNAK if not. If the latter, then
the client should do a DHCPDISCOVER.

this is confirmed by the server log:
------------------------------------------------------------------
Oct 24 12:52:04 router-pi dhcpd[1068]: DHCPREQUEST for 192.168.1.254
from 0c:60:76:6c:e6:6f (tony-lt) via eth0
Oct 24 12:52:04 router-pi dhcpd[1068]: DHCPACK on 192.168.1.254 to
0c:60:76:6c:e6:6f via eth0
Oct 24 12:52:24 router-pi dhcpd[1068]: DHCPREQUEST for 192.168.1.244
from f4:81:39:82:53:c4 via eth0
Oct 24 12:52:24 router-pi dhcpd[1068]: DHCPACK on 192.168.1.244 to
f4:81:39:82:53:c4 via eth0
Oct 24 12:52:32 router-pi dhcpd[1068]: DHCPREQUEST for 192.168.1.254
from 0c:60:76:6c:e6:6f via eth0
Oct 24 12:52:32 router-pi dhcpd[1068]: DHCPACK on 192.168.1.254 to
0c:60:76:6c:e6:6f (tony-lt) via eth0
Oct 24 12:52:41 router-pi dhcpd[1068]: reuse_lease: lease age 9 (secs)
under 25% threshold, reply with unaltered, existing lease for 192.168.1.254
Oct 24 12:52:41 router-pi dhcpd[1068]: DHCPREQUEST for 192.168.1.254
from 0c:60:76:6c:e6:6f (tony-lt) via eth0
Oct 24 12:52:41 router-pi dhcpd[1068]: DHCPACK on 192.168.1.254 to
0c:60:76:6c:e6:6f (tony-lt) via eth0
------------------------------------------------------------------

Enjoy your sausage rolls!

Cheers, Tony

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#201569

From	deloptes <deloptes@gmail.com>
Date	2018-10-23 22:00 +0200
Message-ID	<wMb0m-1if-11@gated-at.bofh.it>
In reply to	#201544

Tony van der Hoff wrote:

> Any suggestions, please?

I would put host declaration after subnet - don't think it makes difference

also check /etc/hosts for left overs and for the lease take care that your
computers update time with ntp regularly

regards

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#201578

From	tony <lists@vanderhoff.org>
Date	2018-10-24 11:00 +0200
Message-ID	<wMnbb-9q-1@gated-at.bofh.it>
In reply to	#201569

On 23/10/2018 21:57, deloptes wrote:
> Tony van der Hoff wrote:
> 
>> Any suggestions, please?
> 
> I would put host declaration after subnet - don't think it makes difference
> 
You're right -- it doesn't!

> also check /etc/hosts for left overs and for the lease take care that your
> computers update time with ntp regularly
> 
Thanks - all those are in order.
Cheers, tony

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#201574

From	Reco <recoverym4n@enotuniq.net>
Date	2018-10-24 08:30 +0200
Message-ID	<wMkQ1-7lk-3@gated-at.bofh.it>
In reply to	#201544

	Hi.

On Tue, Oct 23, 2018 at 03:56:34PM +0200, Tony van der Hoff wrote:
> The DHCP server is another Stretch system, with the stanzas
> host tony-lt {
> 	hardware ethernet 0c:60:76:6c:e6:6f;
> 	fixed-address 192.168.1.199;
> 	}
> subnet 192.168.1.0 netmask 255.255.255.0
> 	{
>         range 192.168.1.200 192.168.1.254;
>         option routers 192.168.1.10;
> 	}
> 
> That MAC is correct for the laptop.
> 

> Finally, the server shows:
> Oct 23 14:23:38 routerpi dhcpd[1068]: DHCPREQUEST for 192.168.1.253 from
> 0c:60:76:6c:e6:6f (tony-lt) via eth0
> Oct 23 14:23:38 routerpi dhcpd[1068]: DHCPACK on 192.168.1.253 to
> 0c:60:76:6c:e6:6f (tony-lt) via eth0
> Oct 23 14:23:53 routerpi dhcpd[1068]: reuse_lease: lease age 15 (secs)
> under 25% threshold, reply with unaltered, existing lease for 192.168.1.253
> Oct 23 14:23:53 routerpi dhcpd[1068]: DHCPREQUEST for 192.168.1.253 from
> 0c:60:76:6c:e6:6f (tony-lt) via eth0
> Oct 23 14:23:53 routerpi dhcpd[1068]: DHCPACK on 192.168.1.253 to
> 0c:60:76:6c:e6:6f (tony-lt) via eth0
> 
> So, my question: why is the server handing out .253, when it is
> configured to provide .199?

Because client specifically asks for .253 address:

> Oct 23 14:23:38 routerpi dhcpd[1068]: DHCPREQUEST for 192.168.1.253 from
> 0c:60:76:6c:e6:6f (tony-lt) via eth0

And, to quote dhcpd.conf:

There may be a host declaration matching the client’s identification. If
that host declaration contains a fixed-address declaration that lists an
IP address that is valid for the network segment to which the client is
connected. In this case, the DHCP server will never do dynamic address
allocation. In this case, the client is required to take the address
specified in the host declaration. If the client sends a DHCPREQUEST for
some other address, the server will respond with a DHCPNAK.

When the DHCP server allocates a new address for a client (remember,
this only happens if the client has sent a DHCPDISCOVER), it first looks
to see if the client already has a valid lease on an IP address, or if
there is an old IP address the client had before that hasn’t yet been
reassigned. In that case, the server will take that address and check it
to see if the client is still permitted to use it. If the client is no
longer permitted to use it, the lease is freed if the server thought it
was still in use - the fact that the client has sent a DHCPDISCOVER
proves to the server that the client is no longer using the lease.

You assume that a 'host' entry overrides any previous IP assignment.
It's not.

> What is this 'reuse-lease' all about?

Your DHCP client renews the leased IP although the lease time is not
expired. Not relevant to this problem.

> I've tried 'dhclient -r wlan 0; dhclient -v wlan0' on the laptop, to no
> avail.

I'd be really surprised if it did change something. Your DHCP server has
a problem, client does not.

> Any suggestions, please?

Clear your DHCP lease file on DHCP server. Bounce the thing. Check
again.

Reco

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#201584

From	tony <lists@vanderhoff.org>
Date	2018-10-24 13:30 +0200
Message-ID	<wMpwl-1Ej-3@gated-at.bofh.it>
In reply to	#201574

On 24/10/2018 08:19, Reco wrote:
> 	Hi.
> 
> On Tue, Oct 23, 2018 at 03:56:34PM +0200, Tony van der Hoff wrote:
>> The DHCP server is another Stretch system, with the stanzas
>> host tony-lt {
>> 	hardware ethernet 0c:60:76:6c:e6:6f;
>> 	fixed-address 192.168.1.199;
>> 	}
>> subnet 192.168.1.0 netmask 255.255.255.0
>> 	{
>>         range 192.168.1.200 192.168.1.254;
>>         option routers 192.168.1.10;
>> 	}
>>
>> That MAC is correct for the laptop.
>>
> 
>> Finally, the server shows:
>> Oct 23 14:23:38 routerpi dhcpd[1068]: DHCPREQUEST for 192.168.1.253 from
>> 0c:60:76:6c:e6:6f (tony-lt) via eth0
>> Oct 23 14:23:38 routerpi dhcpd[1068]: DHCPACK on 192.168.1.253 to
>> 0c:60:76:6c:e6:6f (tony-lt) via eth0
>> Oct 23 14:23:53 routerpi dhcpd[1068]: reuse_lease: lease age 15 (secs)
>> under 25% threshold, reply with unaltered, existing lease for 192.168.1.253
>> Oct 23 14:23:53 routerpi dhcpd[1068]: DHCPREQUEST for 192.168.1.253 from
>> 0c:60:76:6c:e6:6f (tony-lt) via eth0
>> Oct 23 14:23:53 routerpi dhcpd[1068]: DHCPACK on 192.168.1.253 to
>> 0c:60:76:6c:e6:6f (tony-lt) via eth0
>>
>> So, my question: why is the server handing out .253, when it is
>> configured to provide .199?
> 
> Because client specifically asks for .253 address:
> 
>> Oct 23 14:23:38 routerpi dhcpd[1068]: DHCPREQUEST for 192.168.1.253 from
>> 0c:60:76:6c:e6:6f (tony-lt) via eth0
> 

Agree fully.

> And, to quote dhcpd.conf:
> 
> There may be a host declaration matching the client’s identification. If
> that host declaration contains a fixed-address declaration that lists an
> IP address that is valid for the network segment to which the client is
> connected. In this case, the DHCP server will never do dynamic address
> allocation. In this case, the client is required to take the address
> specified in the host declaration. If the client sends a DHCPREQUEST for
> some other address, the server will respond with a DHCPNAK.
> 

Yes, agree again.

> When the DHCP server allocates a new address for a client (remember,
> this only happens if the client has sent a DHCPDISCOVER), it first looks
> to see if the client already has a valid lease on an IP address, or if
> there is an old IP address the client had before that hasn’t yet been
> reassigned. In that case, the server will take that address and check it
> to see if the client is still permitted to use it. If the client is no
> longer permitted to use it, the lease is freed if the server thought it
> was still in use - the fact that the client has sent a DHCPDISCOVER
> proves to the server that the client is no longer using the lease.
>>
> You assume that a 'host' entry overrides any previous IP assignment.
> It's not.
> 

No, When a client issues a DHCPREQUEST which the server doesn't like,
the server should issue a DHCPNAK, to which the client will respond with
a DHCPDISCOVER. The server is not sending the NAK. This, I believe to be
the crux of the matter. The 'host' assignment should cause the server to
send a DHCPNAK.

> 
>> What is this 'reuse-lease' all about?
> 
> Your DHCP client renews the leased IP although the lease time is not
> expired. Not relevant to this problem.
>>
>> I've tried 'dhclient -r wlan 0; dhclient -v wlan0' on the laptop, to no
>> avail.
> 
> I'd be really surprised if it did change something. Your DHCP server has
> a problem, client does not.
> 

I agree again, but when one gets desperate, one starts to grasp at straws.

> 
>> Any suggestions, please?
> 
> Clear your DHCP lease file on DHCP server. Bounce the thing. Check
> again.
> 

Yes, I've done that. No change I'm afraid.

Cheers, Tony

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csiph-web

strange DHCP behaviour

Contents

#201544 — strange DHCP behaviour

#201545

#201556

#201551

#201553

#201559

#201563

#201566

#201576

#201564

#201568

#201577

#201579

#201580

#201582

#201583

#201569

#201578

#201574

#201584