[pkg-dhcp-devel] Bug#675372: Bug#675372: isc-dhcp-client: dhclient wastes one minute at boot time on an unplugged link

[Andrew Pollock]

On Fri, Jun 15, 2012 at 09:17:11PM -0700, Andrew Pollock wrote:
> 
> I've found the culprit: it's 0.7~rc1+experimental of ifupdown.
> 
> Sounds like you folks must have the ifupdown from experimental installed.
> 
> Also Cc'ing the ifupdown maintainer (whoa, it's not aj any more?)
> I'll have to review #420784 and try to understand what problem is trying to be
> solved with adding the -1 flag to dhclient, but that's the cause.
> 
> In the meantime, you can work around this by adding 
> 
> timeout 10;
> 
> to your dhclient.conf. Adjust 10 up or down to taste.

I may have spoken too soon. There's no noticeable time difference between a
run of dhclient with or without the -1 option (although I'd have thought
we'd want dhclient to hang around in the background in case a cable was
subsequently plugged in, so I still don't think that adding -1 to how
ifup invokes dhclient is a particularly desirable thing)

$ time sudo dhclient -v eth0
Internet Systems Consortium DHCP Client 4.2.2
Copyright 2004-2011 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/

Listening on LPF/eth0/f0:de:f1:ad:cb:df
Sending on   LPF/eth0/f0:de:f1:ad:cb:df
Sending on   Socket/fallback
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 7
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 14
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 8
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 13
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 15
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 4
No DHCPOFFERS received.
No working leases in persistent database - sleeping.

real	1m12.207s
user	0m0.032s
sys	0m0.012s

$ time sudo dhclient -v -1 eth0
Internet Systems Consortium DHCP Client 4.2.2
Copyright 2004-2011 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/

Listening on LPF/eth0/f0:de:f1:ad:cb:df
Sending on   LPF/eth0/f0:de:f1:ad:cb:df
Sending on   Socket/fallback
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 7
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 15
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 16
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 13
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 10
No DHCPOFFERS received.
Unable to obtain a lease on first try.  Exiting.

real	1m1.685s
user	0m0.024s
sys	0m0.012s

I don't feel like this behaviour (how long it tries to get a lease) is
particularly new though. I agree it is rather obnoxious though, so I'm
inclined to address this by shipping a dhclient.conf that sets a lower
timeout. I'm just not sure how much I want to experiment with shorter
timeouts this close to the freeze.
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