Dhclient not sending DHCPDISCOVER after reason=TIMEOUT

[Vasanth Ragavendran]

Hi,

I am using ISC dhclient 4.3.1 on my debian 8.3 Linux. When the reason
reported by dhclient is TIMEOUT (as there is a valid lease in leases
file), and if the DHCP server is unreachable(from which the last time
the lease was obtained) then the dhclient-script exits with status 2.
The dhclient is not sending DHCPDISCOVER msgs after this. Why is this
so?
However, when the reason reported by dhclient is FAILED, the dhclient
keeps sending DHCPDISCOVER msgs periodically. Note that the timeout
and retry values in dhclient.conf are 8 seconds and 1 second
respectively.

There can be a scenario where the DHCP server is unreachable now (from
last time when a valid lease was obtained from the DHCP server),
because its down or something, but can be available later. In such a
case, with valid lease in leases file if $reason is TIMEOUT, the
dhclient is not sending DHCPDISCOVER periodically. I am using
ifup/ifdown scripts to manage the network connectivity. Awaiting your
reply.

Thanks and Regards,
R. Vasanth Ragavendran.
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[Vasanth Ragavendran]

Found the issue. It was due to dhclient-script wrongly interpreting
the exit status, due to which the exit status always turned out to be
0 and hence "if (!script_go (client))" in state_panic function always
turned out to be true, there by putting the dhclient in BOUND state
and not starting a timer to send the DHCPDISCOVER.

On Thu, Oct 27, 2016 at 4:01 PM, Vasanth Ragavendran
<[hidden email]> wrote:

> Hi,
>
> I am using ISC dhclient 4.3.1 on my debian 8.3 Linux. When the reason
> reported by dhclient is TIMEOUT (as there is a valid lease in leases
> file), and if the DHCP server is unreachable(from which the last time
> the lease was obtained) then the dhclient-script exits with status 2.
> The dhclient is not sending DHCPDISCOVER msgs after this. Why is this
> so?
> However, when the reason reported by dhclient is FAILED, the dhclient
> keeps sending DHCPDISCOVER msgs periodically. Note that the timeout
> and retry values in dhclient.conf are 8 seconds and 1 second
> respectively.
>
> There can be a scenario where the DHCP server is unreachable now (from
> last time when a valid lease was obtained from the DHCP server),
> because its down or something, but can be available later. In such a
> case, with valid lease in leases file if $reason is TIMEOUT, the
> dhclient is not sending DHCPDISCOVER periodically. I am using
> ifup/ifdown scripts to manage the network connectivity. Awaiting your
> reply.
>
> Thanks and Regards,
> R. Vasanth Ragavendran.

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