dhcpcd-discuss

On Monday 20 July 2009 17:22:09 Thomas Marcks von Würtemberg wrote:
> I'm hoping that this is the right place to post this. If not, pleas
> tell me where i shud post it.

This is the right place :)

> I think ther is some form of racecondition in the dhcpcd. I cant get
> an address when im at my scool, it takes like 3-4 tryes to get one.
> They have checked ther servers and dont think its a config miss. Im
> running arch linux, so i think the dhcpcd version is dhcpcd 5.0.6-1.
> Below is the output from dhcpcd:
>
> bash-3.2# dhcpcd wlan0
> dhcpcd: version 5.0.4 starting
> dhcpcd: wlan0: broadcasting for a lease
> dhcpcd: wlan0: offered 194.47.156.241 from 194.47.156.1
> 'fagott.net.bth.se'
> dhcpcd: wlan0: ignoring offer of 194.47.157.97 from 194.47.157.1
> 'bore.net.bth.se'
> dhcpcd: wlan0: acknowledged 194.47.156.241 from 194.47.156.1
> 'fagott.net.bth.se'
> dhcpcd: wlan0: checking for 194.47.156.241
> dhcpcd: wlan0: NAK: requested address not available from 194.47.157.1
> dhcpcd: wlan0: broadcasting for a lease
> dhcpcd: wlan0: offered 194.47.156.241 from 194.47.156.1
> 'fagott.net.bth.se'
> dhcpcd: wlan0: ignoring offer of 194.47.157.97 from 194.47.157.1
> 'bore.net.bth.se'
> dhcpcd: wlan0: acknowledged 194.47.156.241 from 194.47.156.1
> 'fagott.net.bth.se'
> dhcpcd: wlan0: checking for 194.47.156.241
> dhcpcd: wlan0: NAK: requested address not available from 194.47.157.1
> dhcpcd: wlan0: broadcasting for a lease
> dhcpcd: wlan0: offered 194.47.156.241 from 194.47.156.1
> 'fagott.net.bth.se'
> dhcpcd: wlan0: ignoring offer of 194.47.157.97 from 194.47.157.1
> 'bore.net.bth.se'
> dhcpcd: wlan0: acknowledged 194.47.156.241 from 194.47.156.1
> 'fagott.net.bth.se'
> dhcpcd: wlan0: checking for 194.47.156.241
> dhcpcd: wlan0: NAK: requested address not available from 194.47.157.1
> dhcpcd: wlan0: broadcasting for a lease
> dhcpcd: wlan0: offered 194.47.156.241 from 194.47.156.1
> 'fagott.net.bth.se'
> dhcpcd: wlan0: ignoring offer of 194.47.157.97 from 194.47.157.1
> 'bore.net.bth.se'
> dhcpcd: wlan0: acknowledged 194.47.156.241 from 194.47.156.1
> 'fagott.net.bth.se'
> dhcpcd: wlan0: checking for 194.47.156.241
> dhcpcd: wlan0: NAK: requested address not available from 194.47.157.1
>
> it continues like this untill reciving a timeout or sucessing with
> getting a lease. Dose anybody have any ide whats wrong hear? I will
> try to get some tcpdumps for further investigation.

Race condition? Maybe. From the looks of things there are two DHCP servers on 
the network and one is NAKing the other. This IS a server misconfiguration as I 
would imagine they should be failover, not NAK each other ;)

If you can get a bootp packet trace of this, either from wireshark or tcpdump 
then you can see DHCP requesting the address with the correct ServerID. 
Infact, I would do this anyway, and email the packet dump here or to me 
directly so I can analyse it.

Aside from proving that the servers are mis-configured, you can also download 
dhcpcd-5.0.6 which will fix this problem for you by not listening to any NAK 
messages after being given an offer.

Thanks

Roy