Forcing expiration of DHCP lease

[Dan Jenkins]

Fred wrote:

>On Thu, 2004-06-03 at 10:58, Dan Jenkins wrote:
>  
>
>>On Thu, 3 Jun 2004, Michael ODonnell wrote:
>>    
>>
>...
>  
>
>>The simplest thing would be for the Windows sysadmin
>>to just delete the lease and let it be reassigned.
>>It ought not be but a minute to do. (I am not in
>>front of one of my Windows servers, so I can't tell
>>you exactly what steps to do.)
>>
>>Alternatively, you could force your system to have
>>the same IP that it had when it was called "linux."
>>    
>>
>
>Well, isn't the main point he is looking for is not so much what the IP
>is, but the name assigned to that IP address?
>  
>
 From what I understand of Windows DHCP, they are part & parcel of the 
same thing.
When DHCP issues an IP to a system, it also registers the host name in 
DNS and possibly
WINS (depending on configuration, I guess). (I'm more familiar with the 
details of Samba
then Windows itself.)

>I'm too lazy to wade through the RFC on this, but is name assignment a
>part of the DHCP protocol, or part of Microsoft's "Embrace, Extend,
>Extinguish" approach?
>  
>
I browsed the RFC, which doesn't seem to mention host names in it.

 From reading the RFC, releasing a lease is supposed to terminate the 
lease term. In my experience,
Windows, at least, continues to reissue the same IP to the same MAC, 
even after a DHCP release.

I'm puzzled over why the DHCP server would be issuing "linux-1". That 
doesn't sound like
right behavior. Typically the CLIENT sends its host name, which is what 
gets registered by
the DHCP server into DNS. I know you can do the reverse, but I thought 
you had to manually
assign the host name based on MAC. So, it would be the Windows 
sysadmin's responsibility
to manually assign the name "linux-1" (or re-assign the name "linux").

In any event, spoofing the MAC address of the previous NIC would be the 
most seamless solution.
Or having the Windows sysadmin delete the lease.

-- 
Dan Jenkins (dan at rastech.com)
Rastech Inc., Bedford, NH, USA --- 1-603-624-7272
*** Technical Support for over a Quarter Century