client request preferred IP address

Evan Hunt Evan_Hunt at
Wed Jul 18 21:11:52 UTC 2007

> 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  If the prior lease is no
longer active, then you might need to muck with its expiry date to get the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.

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