Relay agents, NAT, and offers to giaddr

Alan DeKok adekok at
Fri Sep 15 21:10:36 UTC 2006

Simon Hobson wrote:
> It doesn't deal with the client renewing though. That would need 
> significant rewriting of the server to handle renewal requests that 
> come from a different IP address to the lease being renewed. IFF you 
> think you can write a workable method for dealing with it, then the 
> way to address it is through the standards bodies - good luck !

   Maybe I'm crazy, but my tests with ISC & a hacked-up test client 
indicate that so long as giaddr is set, that's where the reply goes. 
I've successfully had it renew leases for IP address X that were unicast 
from IP Y (i.e. giaddr).

> The complications are significant. I personally do not believe that 
> the effort involved would be worth it since there are always 
> alternatives. In any case, this is only the second or third time in a 
> good few years that I can recall the question being asked - hardly a 
> mass request !

   Yeah, I was just playing Devil's advocate...

   Alan DeKok.

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