3.1.0 failover and dynamic bootp clients

Carlos Vicente cvicente at network-services.uoregon.edu
Mon Aug 13 20:33:05 UTC 2007

Simon Hobson wrote:
> I believe it is, but the times don't look right. AIUI, for dhcp 
> clients under failover, both servers will respond to a client and 
> offer different addresses from their free pool. They will create a 
> short lease of 2 mins duration so as to 'reserve' the address should 
> the client decide to accept the offer. The client will pick an offer 
> (typically the first it receives) and request it from the server that 
> offered it, and the server will confirm it - offering a longer lease. 
> The offer which was not accepted will simply expire and the address 
> will return to the free pool. At each stage, the servers will 
> communicate the lease state changes to each other.

I'm not sure that's a correct description of the failover protocol

> So I would expect one server to show a lease that was only valid for 
> 2 minutes and then expired - but I don't know if it's different for 
> bootp clients. If it is, then this would be a simple attack vector 
> for a malicious client since it does not even have to keep up a 
> decent request rate to keep a pool exhausted !

bootp is a totally different protocol.  There is no confirmation from
the client.  So yes, the operation you described would not work with
bootp clients, even if it was accurate.

I still think that what I'm seeing is a bug.


More information about the dhcp-users mailing list