> That series of commands releases the lease in the server, so that the
> server could then offer it to a different client. However, I don't believe
> there is any part of the DHCP protocol for the server to contact the
> client and tell it to release the lease. So the original client can
> continue to use the address until the original lease time expires.
>
> If the client did not respond to the ping before offer, the server could
> then offer the lease to a second client.
>
> regards,
> Glenn Satchell
>
> On Tue, August 22, 2017 11:38 pm, Thomas Markwalder wrote:
>> Hello all:
>>
>> It is possible to connect to ISC_DHCP via omshell and change the lease
>> state to released as
>> shown below. The following example you're connecting from the machine
>> ISC_DHCP
>> is running on and you didn't specify a key in the server config:
>>
>>
>> 1. Start omshell and connect to ISC DHCP:
>>
>> ---------------------------------------------
>> centos64 isc_dhcp $ tip/bin/omshell
>>> server localhost
>>> port 7911
>>> connect
>> obj: <null>
>> ----------------------------------------------
>>
>>
>> 2. Create a new lease object and set the ip-address to
>> the address of the desired lease:
>> ----------------------------------------------
>>> new lease
>> obj: lease
>>> set ip-address=178.16.1.127
>> omapi_set_value (ip-address, 4 18bed8c)
>> Â ==> success
>> obj: lease
>> ip-address = b2:10:01:7f
>> ----------------------------------------------
>>
>> 3. Fetch the lease via the open object command
>> ----------------------------------------------
>>> open
>> omapi_set_value (op, 1)
>> Â ==> success
>> Â Â :
>> Â Â :
>> obj: lease
>> ip-address = b2:10:01:7f
>> state = 00:00:00:02
>> subnet = 00:00:00:02
>> pool = 00:00:00:03
>> hardware-address = 08:00:27:99:72:be
>> hardware-type = 00:00:00:01
>> ends = 59:9c:30:bc
>> starts = 59:9c:2f:90
>> tstp = 00:00:00:00
>> tsfp = 00:00:00:00
>> atsfp = 00:00:00:00
>> cltt = 59:9c:2f:90
>> flags = 00
>> ----------------------------------------------
>>
>> 4. Set the lease state to FTS_RELEASED (i.e. 4)
>> ----------------------------------------------
>> set state=4
>> omapi_set_value (state, 4)
>> Â ==> success
>> obj: lease
>> ip-address = b2:10:01:7f
>> state = 4
>> subnet = 00:00:00:02
>> pool = 00:00:00:03
>> hardware-address = 08:00:27:99:72:be
>> hardware-type = 00:00:00:01
>> ends = 59:9c:30:bc
>> starts = 59:9c:2f:90
>> tstp = 00:00:00:00
>> tsfp = 00:00:00:00
>> atsfp = 00:00:00:00
>> cltt = 59:9c:2f:90
>> flags = 00
>> ----------------------------------------------
>>
>>
>> 5. Save the change via the update object command:
>> ----------------------------------------------
>>> update
>> omapi_set_value (op, 3)
>> Â ==> success
>> omapi_set_value (object, dhcpctl-remote)
>> Â ==> success
>> omapi_set_value (handle, 4)
>> Â ==> success
>> omapi_set_value (result, 4 18c03fc)
>> Â ==> success
>> obj: lease
>> ip-address = b2:10:01:7f
>> state = 4
>> subnet = 00:00:00:02
>> pool = 00:00:00:03
>> hardware-address = 08:00:27:99:72:be
>> hardware-type = 00:00:00:01
>> ends = 59:9c:30:bc
>> starts = 59:9c:2f:90
>> tstp = 00:00:00:00
>> tsfp = 00:00:00:00
>> atsfp = 00:00:00:00
>> cltt = 59:9c:2f:90
>> flags = 00
>> ----------------------------------------------
>>
>> omshell(1) discusses this in general terms. dhcpd.conf(5) describes how
>> to configure ISC_DHCP for OMAPI connections.
>>
>>
>> Regards,
>>
>> Thomas Markwalder
>> ISC Software Engineering
>>
>>
>> On 8/22/17 8:47 AM, perl-list wrote:
>>> To my knowledge, there is no such method available. Â The client is
>>> leased the address until a certain expire period. Â There is no way to
>>> tell the client to stop using the address early.Â
>>>
>>> ------------------------------------------------------------------------
>>>
>>> *From: *"Maneesh Kumar" <
[hidden email]>
>>> *To: *
[hidden email]
>>> *Sent: *Tuesday, August 22, 2017 7:47:30 AM
>>> *Subject: *Mechanism for forcing release of lease from the DHCP
>>> server end
>>>
>>> Dear Members,
>>>
>>> Kindly let me know if there is a mechanism available for forcing
>>> release of lease from the DHCP server end.
>>>
>>> If yes, please let me know the way to achieve the same.
>>>
>>>
>>> Maneesh Kumar
>>>
>>> HPC Infrastructure and Ecosystem Group
>>> Centre for Development of Advanced Computing
>>>
>>>
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