Dhclient makes system unresponsive with very short leases

[Simon Matter]

> Simon Matter wrote:
>
>>Steps to Reproduce:
>>1. Configure a dhcp server with 'dhcp-lease-time 2'
>>2. Start 'dhclient' on a client
>
> That's a seriously stupid setting, so if you are seeing that on a
> real network, then it's being run by pillocks !

I know it's stupid. Anyway it's a quite "interesting" setup because the IP
address I get is always close to the DHCP server, like so:

May  6 17:44:09 localhost dhclient: DHCPDISCOVER on usb0 to
255.255.255.255 port 67 interval 6
May  6 17:44:09 localhost dhclient: DHCPOFFER from 10.142.111.145
May  6 17:44:09 localhost dhclient: DHCPREQUEST on usb0 to 255.255.255.255
port 67
May  6 17:44:09 localhost dhclient: DHCPACK from 10.142.111.145
May  6 17:44:09 localhost NET[6097]: /sbin/dhclient-script : updated
/etc/resolv.conf
May  6 17:44:13 localhost dhclient: bound to 10.142.111.144 -- renewal in
26 seconds.
May  6 17:44:39 localhost dhclient: DHCPREQUEST on usb0 to 10.142.111.145
port 67
May  6 17:44:39 localhost dhclient: DHCPACK from 10.142.111.145
May  6 17:44:39 localhost dhclient: bound to 10.142.111.144 -- renewal in
431 seconds.
May  6 17:51:50 localhost dhclient: DHCPREQUEST on usb0 to 10.142.111.145
port 67
May  6 17:51:50 localhost dhclient: DHCPACK from 10.142.111.145
May  6 17:51:50 localhost dhclient: bound to 10.142.111.144 -- renewal in
400 seconds.
May  6 17:58:30 localhost dhclient: DHCPREQUEST on usb0 to 10.142.111.145
port 67
May  6 17:58:30 localhost dhclient: DHCPACK from 10.142.111.145
May  6 17:58:30 localhost dhclient: bound to 10.142.111.144 -- renewal in
26 seconds.
May  6 17:58:56 localhost dhclient: DHCPREQUEST on usb0 to 10.142.111.145
port 67
May  6 17:58:56 localhost dhclient: DHCPACK from 10.142.111.145
May  6 17:58:56 localhost dhclient: bound to 10.142.111.144 -- renewal in
28 seconds.
May  6 17:59:24 localhost dhclient: DHCPREQUEST on usb0 to 10.142.111.145
port 67
May  6 17:59:24 localhost dhclient: DHCPACK from 10.142.111.145
May  6 17:59:24 localhost dhclient: bound to 10.142.111.144 -- renewal in
409 seconds.
May  6 18:06:13 localhost dhclient: DHCPREQUEST on usb0 to 10.142.111.145
port 67
May  6 18:06:13 localhost dhclient: DHCPACK from 10.142.111.145
May  6 18:06:13 localhost dhclient: bound to 10.142.111.144 -- renewal in
25 seconds.
May  6 18:06:38 localhost dhclient: DHCPREQUEST on usb0 to 10.142.111.145
port 67
May  6 18:06:38 localhost dhclient: DHCPACK from 10.142.111.145
May  6 18:06:38 localhost dhclient: bound to 10.142.111.144 -- renewal in
407 seconds.
May  6 18:13:25 localhost dhclient: DHCPREQUEST on usb0 to 10.142.111.145
port 67
May  6 18:13:25 localhost dhclient: DHCPACK from 10.142.111.145
May  6 18:13:25 localhost dhclient: bound to 10.142.111.144 -- renewal in
376 seconds.

Whatever address I get the server seems always to be right next to the
client.
But, if my client gets those stupid leases, it should handle them somehow.
The log above shows that where it renews in 26 or 28 seconds instead of 0
seconds.

Simon