[pkg-ntp-maintainers] Bug#683061: Bug#683061: Bug#683061: bug report #683061

[Klaus Ethgen]

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Let me try to get that bug (and all the others) fixed..

Am Di den  2. Jul 2013 um 14:57 schrieb Kurt Roeckx:
> On Tue, Jul 02, 2013 at 03:32:13PM +0200, Thomas Hood wrote:
> > On Tue, Jul 2, 2013 at 1:59 PM, Kurt Roeckx <kurt at roeckx.be> wrote:
> > 
> > > Do you know NXDOMAIN returns?  I think it returns just the same?
> > >
> > 
> > 
> > I don't immediately see how getaddrinfo() alone can be used to tell
> > whether or not an actual NXDOMAIN was received. A test with a small
> > C program reveals that retval -11 errno 2 is returned both in the
> > NXDOMAIN case and in the case where no nameservers could be found.
> 
> And I think that a nameserver not found should never have resulted
> in that return value, since it's not a permanent error.

Well, Kurt, from the system perspective it is a permanent error (in
fact, it is a negative answer, not a permanent error.)

nsswitch.conf has "file dns" (usually) for DNS. As /etc/resolv.conf is
empty at that stage, it answers the name request only with the knowledge
of /etc/hosts. After that, NTP knows that the name does not exist.

Then, lexically after NTP, the DNS server (unbound in my case, note that
bind9 is lexically before NTP) is started and populate /etc/resolv.conf
via resolvconf with proper settings. After that the names could get
resolved but NTP will never try again.

So a working $named is essential to NTP. As mentioned many times now by
different people, $named is a virtual target that optionally depends on
running DNS. (If you have no local DNS, usually /etc/resolv.conf gets
populated by $network target)

So the only correct solution _is_ to add $named to the Required-Start
setting! There is no other way that addresses all cases of this problem.
And it it the only valid solution.

So, please, please, get that $named target into Required-Start. For my
part, let Helmut Grohne upload that really small and proper NMU. This
bug is now more than 3 years old and many people suffer from it. For the
fact that NTP is a essential part in the system in many cases, that
serious problem needs to get addressed.

> > * Computers are mobile these days and DNS also changes from the
> > perspective of those computers. A laptop may connect sometimes
> > to a LAN where the domain name ntp.somecorp.private resolves to
> > the address of a time server.  On other LANs this name does not exist.
> 
> Do you expect the DHCP server on the LAN then to set that ntp
> server?  Currently this would now result in ntpd getting restarted
> by dhcp and should get you a working ntp server.

Yes. That script needs to get back to the hook directories for that
reason.

Generally, the mobile approach is a slightly different problem than the
one on a server. For a server, not running NTP might be fatal, for a
mobile device it is just a small problem.

Regards
   Klaus
- -- 
Klaus Ethgen                              http://www.ethgen.ch/
pub  4096R/4E20AF1C 2011-05-16   Klaus Ethgen <Klaus at Ethgen.ch>
Fingerprint: 85D4 CA42 952C 949B 1753  62B3 79D0 B06F 4E20 AF1C
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