dhclient: ISP's server won't answer unicast DHCPREQUEST anymore

[Steve Clark]

On 12/12/2011 03:15 AM, Jordan Russell wrote:
> A bizarre problem has appeared after upgrading from Fedora 14 to 15,
> which brought dhclient from 4.2.0-P2 to 4.2.1-P1.
>
> Since the upgrade (weeks ago), my ISP's DHCP server no longer responds
> to any of the unicast DHCPREQUEST packets sent by dhclient when it
> enters the RENEWING state. However, hours later, when dhclient reaches
> the REBINDING state and broadcasts instead, the server responds
> immediately, and the renewal succeeds.
>
>    DHCPREQUEST on eth1 to 10.72.0.1 port 67
>    DHCPREQUEST on eth1 to 10.72.0.1 port 67
>    DHCPREQUEST on eth1 to 10.72.0.1 port 67
>    [...]
>    DHCPREQUEST on eth1 to 255.255.255.255 port 67
>    DHCPACK from 10.72.0.1
>    bound to 76.x.x.x -- renewal in 14685 seconds.
>
> tcpdump confirms that the unicast DHCPREQUEST packets are making it out
> (with correct IP and MAC addresses), but no corresponding responses are
> coming in.
>
> Was there any change in dhclient 4.2.1 that might explain this? I'm
> using an empty dhclient.conf file just as I was prior to the upgrade.
> (Initially, Fedora 15 inserted dhcp-client-identifier and hostname
> settings into the config, but I've since removed both of those and
> restarted dhclient numerous times.)
>
> Also, as an interim workaround to cut back on the syslog spam, is there
> some way to force dhclient to broadcast all DHCPREQUEST packets (i.e.
> skip the RENEWING state)?
>
> Thanks.
I see the same behavior on Fedora 12 with
dhclient-4.1.1-18.P1.fc12.x86_64

...
Dec 11 05:55:43 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 05:55:52 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 05:56:02 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 05:56:23 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 05:56:37 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 05:56:54 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 05:57:08 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 05:57:29 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 05:57:39 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 05:57:55 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 05:58:07 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 05:58:17 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 05:58:24 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 05:58:32 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 05:58:52 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 05:59:09 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 05:59:28 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 05:59:35 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 05:59:43 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 05:59:51 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 06:00:05 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 06:00:25 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 06:00:38 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 06:00:52 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 06:01:06 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 06:01:21 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 06:01:41 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 06:02:02 joker dhclient[1829]: DHCPREQUEST on eth0 to 10.99.32.1 port 67
Dec 11 06:02:23 joker dhclient[1829]: DHCPREQUEST on eth0 to 255.255.255.255 port 67
Dec 11 06:02:23 joker dhclient[1829]: DHCPACK from 10.99.32.1
Dec 11 06:02:23 joker dhclient[1829]: bound to xxx.xxx.xxx.66 -- renewal in 4264 seconds.





-- 
Stephen Clark
*NetWolves*
Sr. Software Engineer III
Phone: 813-579-3200
Fax: 813-882-0209
Email: steve.clark at netwolves.com
http://www.netwolves.com
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