On Wed, Aug 13, 2014 at 07:05:47PM +0100, Steven Chamberlain wrote:
> On 13/08/14 18:05, Cyril Brulebois wrote:
> > What I'd like to get figured out is what changed between images that
> > weren't hitting this problem, and the newly published ones.
>
> What changed is dhclient from isc-dhcp-client-udeb gained a signal
> handler that responds to SIGKILL by releasing the DHCP lease and
> deconfiguring the interfaces. I've just tested that the version in
> wheezy d-i didn't trap the signal; Linux udhcpc doesn't either.
>
> This is a 'feature' introduced in ISC DHCP 4.3.0, which first reached
> testing on 2014-07-16; I've tested that d-i Alpha 1 wasn't affected by
> this bug (dhclient is killed but the interface stays configured) :
>
> > @@ -681,6 +692,10 @@ main(int argc, char **argv) {
> > dmalloc_outstanding = 0;
> > #endif
> >
> > + /* install signal handlers */
> > + signal(SIGINT, dhcp_signal_handler); /* control-c */
> > + signal(SIGTERM, dhcp_signal_handler); /* kill */
> > +
> (from
> http://anonscm.debian.org/gitweb/?p=pkg-dhcp/isc-dhcp.git;a=commitdiff;h=b2a56ecb808768dbc5bd4be60fcf9c9f93d8e802#patch16
> )
>
> Either way, netcfg killing the DHCP client seems wrong to me, because
> I'd expect the kind of issues Philipp Kern described; if you're going
> to use DHCP, you ought to renew your lease and not let it expire?
Ubuntu uses -1, which means they don't have anything left to kill at that
point.
I agree that this killing does not make sense. Especially when the network
configuration is complete you want daemons like dhclient and rdnssd to stick
around in case dynamic configuration changes (rdnssd) and to keep up the
state / communicate own presence on the network (dhclient).
Kind regards
Philipp Kern
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