[Dnsmasq-discuss] Strange dhcp behavior, Problem assigning particular ip's

Simon Kelley simon at thekelleys.org.uk
Tue Jan 30 13:16:24 GMT 2007


Peter Katzmann wrote:
> Hello,
> i have here a d-link printbox. This should change from static to dhcp ip.
> Normally the box has the ip 192.168.2.252 and the hostname druckserv3
> 
> When i configured a dhcp-host entry with ,mac,hostname
> i receive the following messages:
>  DHCPDISCOVER(eth0) 00:80:c8:bd:ac:d8
>  DHCPOFFER(eth0) 192.168.2.252 00:80:c8:bd:ac:d8
>  DHCPREQUEST(eth0) 192.168.2.252 00:80:c8:bd:ac:d8
>  DHCPNAK(eth0) 192.168.2.252 00:80:c8:bd:ac:d8 lease not found
> 
> The same with ip 192.168.2.251
> 
> But strangely with 192.168.2.250 it works:
> DHCPDISCOVER(eth0) 00:80:c8:bd:ac:d8
> DHCPOFFER(eth0) 192.168.2.250 00:80:c8:bd:ac:d8
> DHCPREQUEST(eth0) 192.168.2.250 00:80:c8:bd:ac:d8
> DHCPACK(eth0) 192.168.2.250 00:80:c8:bd:ac:d8 Drucksrv3
> 
> Well, this ip and the entry is unique, a Xerox Phase with .253 works
> perfectly.
> 
> Any clues ? or hints how to debug this problem ?
> 

My guess is this: the DHCP client in your d-link printbox is broken. Not
all DHCPREQUEST messages are the same, there is one which says "renew an
existing lease" and another which says "create a new lease". I think
that your d-link is sending the first when it means the second. Dnsmasq
is refusing to renew the lease that it doesn't know about, because the
lease might actually be held by _another_ DHCP server on the network. If
you tell dnsmasq that it is the only DHCP server around, using
--dhcp-authoritative, then it will make the best of the situation and
create the lease anyway. I don't know why it works with 192.168.2.250,
maybe the d-link got it right that time, or it noticed the change in IP
number and sent the correct DHCPREQUEST

If that's not the problem, use tcpdump to get some packet captures and
send them to me: it should be fairly easy to see what's going on.


Cheers,

Simon

> Thanks
> 
> peter
> 
> 
> 
> _______________________________________________
> Dnsmasq-discuss mailing list
> Dnsmasq-discuss at lists.thekelleys.org.uk
> http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
> 




More information about the Dnsmasq-discuss mailing list