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Date: Tue, 07 Apr 2015 14:07:56 -0700
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Subject: Re: [BUG?] dhclient sends packets with source IP address that has
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Cc: Brooks Davis <brooks@freebsd.org>
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On 04/07/2015 07:53, Brooks Davis wrote:
> I suppose that since dhclient has been killed and restarted it can't
> know it's on the same network, but in practice you want to try to get
> the same lease again and fall back if it turns out you've moved or your dhcp
> server is broken and lost state.  I don't see how this would hurt anything.

Let's say dhclient is restarted after a while (ex. after the reboot), 
when some other host already has that same IP address. dhclient sends 
the broadcast with it, and the response will be sent to another host, 
which currently has that address, and that other host will discard this 
response. dhclient keeps trying for many seconds, doesn't get any 
response. Then it falls back to sending from 0.0.0.0->255.255.255.255 
(as it should have done in the first place), and immediately gets the 
valid response. The problem delays DHCP handshake, this is how this can 
hurt.

dhclient comes from OpenBSD upstream. It has been discontinued in 
OpenBSD, due to them thinking it has a lot of problems. Maybe FreeBSD 
should also replace dhclient?

Yuri