[ntp:questions] Ntpd and changing IP addresses

Juliusz Chroboczek Juliusz.Chroboczek at pps.jussieu.fr
Tue Oct 9 18:06:03 UTC 2007


Hi,

I'm currently working on a project in which the set of IP addresses of
a host changes a few times after boot.  More precisely, at any time
a host can have

  - a (global or NATed) IPv4 address;
  - a global IPv6 address; or
  - both.

Most hosts only have IPv6 routing most of the time, and may
occasionally have IPv4; such hosts need to have NTP work over IPv6.
Others have IPv4 routing only before they establish a VPN to get to
the IPv6 Internet; such hosts need to have NTP work over IPv4 (the VPN
software requires the time to be accurate).

Obviously, I want all the hosts to have the same NTP config, so I've
configured two IPv4 and two IPv6 servers.  Unfortunately, if ntpd
starts when only IPvx addresses are configured, it discards the IPvy
servers (``couldn't find interface for xxxx'').

Currently, I'm working around that by restarting the ntp daemon
whenever the set of IP addresses changes.  Is there a way to tickle
the ntp daemon so that it notices that the set of IP addresses has
changed?  Even better, is it possible to have ntpd daemon deal
automatically with address changes?

Thanks,

                                        Juliusz



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