Re: multiple «hardware ethernet» for the same IP address

[Simon]

Vincent LE NEZET <vincent.le.nezet at ens.psl.eu> wrote:

> I have a question about the support of multiple mac address for the same IP in isc-dhcp-server.
> 
> The user support team register client's mac address in the dhcp.
> 
> So that clients always have the same IP address, they create two «host» blocks in the conf with the same IP, but two differents mac : one for the ethernet card of the PC and one for the dock on the user's desk.
> 
> Given that it could result in an address conflict, it surprises me that isc-dhcp accept this. Is it because of a RFC ?

Strictly speaking, it violates the RFCs (I think), and if you tried to do it via any other mechanism (classes & subclasses, reservations) it wouldn’t work. But when you use a fixed-address statement, this causes the server to bypass most of the lease handling processes - and in particular there is no check to see if the lease is free (the admin said to do it, so do it on the basis that they (should) know their network).

Simon