[Dnsmasq-discuss] Dhcp issues w/ static leases

[Simon Kelley]

Philip Prindeville wrote:
>  I'm seeing the following:
> 
> Sep 25 20:32:56 pbx daemon.info dnsmasq-dhcp[5192]: DHCPREQUEST(br1)
> 192.168.1.19 f8:1e:df:1e:c2:23
> Sep 25 20:32:56 pbx daemon.info dnsmasq-dhcp[5192]: DHCPACK(br1)
> 192.168.1.19 f8:1e:df:1e:c2:23 iphone3gs
> Sep 25 20:32:56 pbx daemon.info hostapd: ap0: STA f8:1e:df:1e:c2:23
> RADIUS: starting accounting session 4C9EB029-00000001
> Sep 25 20:32:56 pbx daemon.info hostapd: ap0: STA f8:1e:df:1e:c2:23 WPA:
> pairwise key handshake completed (RSN)
> Sep 25 20:32:57 pbx daemon.info dnsmasq-dhcp[5192]: DHCPDECLINE(br1)
> 192.168.1.19 f8:1e:df:1e:c2:23
> Sep 25 20:32:57 pbx daemon.warn dnsmasq-dhcp[5192]: disabling DHCP
> static address 192.168.1.19 for 10m
> Sep 25 20:33:07 pbx daemon.warn dnsmasq-dhcp[5192]: not using configured
> address 192.168.1.19 because it was previously declined
> Sep 25 20:33:10 pbx daemon.info dnsmasq-dhcp[5192]: DHCPDISCOVER(br1)
> f8:1e:df:1e:c2:23
> Sep 25 20:33:10 pbx daemon.info dnsmasq-dhcp[5192]: DHCPOFFER(br1)
> 192.168.1.142 f8:1e:df:1e:c2:23
> Sep 25 20:33:10 pbx daemon.warn dnsmasq-dhcp[5192]: not using configured
> address 192.168.1.19 because it was previously declined
> Sep 25 20:33:10 pbx daemon.info dnsmasq-dhcp[5192]: DHCPDISCOVER(br1)
> f8:1e:df:1e:c2:23
> Sep 25 20:33:10 pbx daemon.info dnsmasq-dhcp[5192]: DHCPOFFER(br1)
> 192.168.1.142 f8:1e:df:1e:c2:23
> Sep 25 20:33:11 pbx daemon.info dnsmasq-dhcp[5192]: DHCPREQUEST(br1)
> 192.168.1.142 f8:1e:df:1e:c2:23
> Sep 25 20:33:11 pbx daemon.info dnsmasq-dhcp[5192]: DHCPACK(br1)
> 192.168.1.142 f8:1e:df:1e:c2:23 iphone3gs
> Sep 25 20:33:11 pbx daemon.warn dnsmasq[5192]: not giving name
> iphone3gs.redfish-solutions.com to the DHCP lease of 192.168.1.142
> because the name exists in /etc/hosts with address 192.168.1.19
> Sep 25 20:33:11 pbx daemon.warn dnsmasq[5192]: not giving name iphone3gs
> to the DHCP lease of 192.168.1.142 because the name exists in /etc/hosts
> with address 192.168.1.19
> 
> 
> I'm running 2.55, and I have an iPhone 3Gs running iOS 4.1.
> 
> Not sure if it's related to Wifi flapping or not.
> 
> Any ideas?
> 

the Iphone is the source of the problem, it's sending the DECLINE
message which says "I don't like this address" to 192.168.1.19 so
dnsmasq is arranging to give it another address instead (192.168.1.142).
Since you've nailed down the name iphone3gs to 192.168.1.19 in
/etc/hosts, this messes up associating the address of the phone with its
name.

There's a small issue that the iPhone first ACKs 192.168.1.19 then
DECLINEs it. By the strict letter of the standard it should do one or
the other, not both. Dnsmasq copes fine with this.

As to why the iPhone should decline 192.168.1.19 I'm not sure. The most
obvious reason is that there's another host on the network which has
192.168.1.19. Most DHCP clients will check for that using ARP and
DECLINE an address is something else appears to be using it.

HTH


Simon.