Bug#400390: [pkg-ntp-maintainers] Bug#400390: Please have ntp installed by default in the standard task

[Olaf van der Spek]

Kurt Roeckx wrote:
> On Mon, Nov 27, 2006 at 09:50:31PM +0100, Olaf van der Spek wrote:
>>> an ntp server, and not to run on a desktop system or something that
>>> doesn't have a static IP address.
>> Why does it require a static IP address?
> 
> It basicly comes down to ntpd currently not supporting changing IP
> addresses.  This is a very longstanding upstream bug, and I don't think
> upstream really is looking into fixing this.

Ah, the need for recvfromto and sendtofrom functions again. :)

> The NTP protocol uses UDP.  If a client sends a packet to a server,
> it expects to get a response from the same IP address back.  This
> creates problems for systems with multiple IP addresses.  Since there
> is no API to get the IP address a packet was send to, it binds to every
> IP address it finds when starting (and to the wildcard address).  So
> depending on the socket, it knows which address it was send too.

Isn't this only an issue for NTP servers and not for clients? I know the 
daemon implements both, but when you don't use it as server it shouldn't 
experience this issue.

> I don't know exactly where the problem is, but after an IP address
> change, packets start to come in at the wildcard socket, and at that
> point things probably stop working.
> 
> See for instance also #399905.
> 
>>> What you might want as a default installation is an sntp client.
>> In that case, shouldn't the Gnome clock panel also enable/disable sntp 
>> instead of ntp then?
> 
> I have no idea what the gnome clock panel can or can't do.  Taking a
> quick look at it, it seems it can synchronize the clock using the 
> internet, but I'm guessing it's editing my ntp.conf or something?
> 
> 
> Kurt