client request preferred IP address

Jeff Weber jweber at
Thu Jul 19 13:58:03 UTC 2007

On my SUSE 10.1 box, I did:

/etc/init.d/network stop

verified my preferred IP address was currently unallocated

edited my preferred IP address into my old leases

/etc/init.d/network start

checked new IP address, which unfortunately never changed from the IP address 
I started with.

Bummer.  The DHCP server is running MSWindows.  I'm probably at the mercy of 
the server, which is remembering my MAC address.

BTW, here's why I'm undertaking this exercise.  Our corporate network is 
nearly 95% MWWindows.  We have no DNS.  My group doesn't have much influence 
with the DHCP server administration.  The DHCP IP addresses tend to be very 
sticky, especially on the Windows boxes.  Some Windows users say their IP 
hasn't moved in years.

We have a few Linux boxes, and often SSH between the Linux boxes.  
I work with the pool of Linux boxes, which see the IP addresses move every few 
months.  The reasons are not fully understood.   When this happens, it's a 
nuisance.  It usually means having to re-memorize the new IP addresses, and 
hunt down and modify every record of previous IP addresses.

It would be a great feature if I could "re-claim" my previous IP address 
immediately after I lose it.

I'm running dhcp-client 3.0.3.


On Wednesday 18 July 2007 16:11, Evan Hunt wrote:
> > I _usually_ have the same IP address assigned by the DHCP server.  Where
> > is this "memory" that tries to give me the same IP address?  If it's in
> > the server, I'm out of luck.  But if the client tells the server the last
> > IP address it held, perhaps this could be exploited.   For example, could
> > I edit the fixed-address line in the last lease I held prior to starting
> > up my dhcp client?
> Yes, that might work.  IIRC, the client sends a requested-address option
> if it finds a still-active lease in its database.  If the prior lease is no
> longer active, then you might need to muck with its expiry date to get the
> client to do the right thing, I'm not sure about that.
> Out of curiosity, why do you need this?
> --
> Evan Hunt -- evan_hunt at
> Internet Systems Consortium, Inc.

Jeff Weber
American Superconductor Corp.

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