Relay agents, NAT, and offers to giaddr

Alan DeKok adekok at
Fri Sep 15 17:30:32 UTC 2006

Bruce Hudson wrote:

>     If the NAT box puts its external address in the giaddr field, the DHCP
> server is going to assign an external address to the client and send this
> back to the NAT box.

   Again, this is an implementation choice.  The giaddr field is simply 
a key.  The DHCP server can respond with allocations for different 
networks based on the giaddr fields, which would seem to be the case here.

   In a similar situation, named has "views".  DHCP could do something 

   I'm not saying it should be done, but just that it's possible.  The 
current method are proven, but that doesn't preclude extending the 
behavior of DHCP implementations.

>     It seems easier just to put a DHCP server on the internal network, or
> build it into the NAT box.

   Yes, that's often the case.

   Alan DeKok.

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