dhclient: lease renewal woes

Glenn Satchell glenn.satchell at uniq.com.au
Wed Aug 29 13:25:27 UTC 2012

Do other dhcp clients (eg windows) work ok with the dhcp server in the
cable modem? Can you look at the settings those clients get from the cable
modem? eg on windows "ipconfig /all"

I would have thought setting the server-identifier to the private
ip-address of the cable modem would be the right thing. Is there anything
you can configure on the cable modem?

Otherwise do you have a system that you could run your own dhcp server on?


On Wed, August 29, 2012 10:47 pm, Mr Dash Four wrote:
>> Correct approach - contact your provider and get them to fix their
>> broken network.
> I know, but lets just say that they are a bit "unresponsive" (to put it
> bluntly, they don't give a damn).
>>> As it stands though, when the lease renewal comes about, my dhclient
>>> becomes "stuck" and I have to restart it.
>> What *should* happen is that as the lease expiry time is looming, the
>> client should try contacting the server directly a few times. If that
>> fails, then shortly before the lease expires, it should try
>> broadcasting the request - at which point you should get your answer.
> That is indeed what happens (I figured this out when requesting a short
> lease just to see how this is going to end), *but* the lease I am
> normally granted from my provider lasts quite long and the time between
> "renew" and "rebind" is a good couple of days. dhclient only tries the
> broadcast approach when the rebind date/time comes about. That means it
> is "trying" to get answers from the external DHCP server non-stop for a
> couple of days!
> Is there a way to force dhclient to stop after x number of tries and use
> the broadcast address instead?
> Also, I tried to force the issue by including as the
> dhcp-server-identifier value by issuing "supersede
> dhcp-server-identifier;" in my dhclient.conf file, but
> that doesn't work because as soon as my cable modem responds to the
> broadcast (using its private IP address) dhclient ignores it as it
> expects answer, quite rightly, from "". Using "supersede
> dhcp-server-identifier <cable_modem_private_ip_address>;" doesn't work
> either. Any ideas?
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