[Dnsmasq-discuss] Probable bug in dnsmasq-2.22

[Simon Kelley]

Ben Klang wrote:
> Hello List,
> 
> I am running dnsmasq-2.22 under OpenWRT.  I have configured address
> reservation using /etc/ethers.  What I have noticed is the configured
> server is handed two IP addresses.  In this case the client is SuSE
> 9.3's dhcpcd.  The result on that system is two IP addresses configured
> as aliases on the interface.  This was a bit surprising.  I was happy
> that the reserved IP was applied, however the second IP is undesirable.
> I was not able to find any mention of this behavior in the list archives
> or on the manpage so I can only assume this is a bug.  I have been able
> to reproduce this condition a number of times now.  Incidentally the
> hostname resolution returns the non-reserved address.
> 
> Example: A host "yeager" was assigned to 192.168.53.2.  When running
> dhcpcd it was configured with both 192.168.53.2 and 192.168.53.238.
> Requesting the IP address for yeager.lan from dnsmasq returns
> 192.168.53.238.
> 
> Thanks for any suggestions.
> /BAK/

Boggle. It's not possible, AFAIK, for a single dhcpcd to get _two_ 
addresses simultaneously. The only way I can see to reproduce the effect 
you are seeing is to run _two_ copies of dhcpcd, one on  the alias, and 
each with  a different client-id.

Note that if two clients are hitting dhcp, each claiming to "yeager" 
then  which address gets assigned to "yeager" is indeterminate, it's 
just whichever interacted with the DHCP server most recently.

If nothing else, could you grab some packet dumps of the interactions 
which lead to this strange state?

Cheers,

Simon.