When separate client and server instances of chronyd are running on one
computer (e.g. for security or performance reasons) and are synchronized
to each other, the server instance provides a reference ID based on the
local address used for synchronization of its NTP clock, which breaks
detection of synchronization loops for its own clients.
Add a "copy" option to specify that the server and client are closely
related, no loop can form between them, and the client should assume the
reference ID and stratum of the server to fix detection of loops between
the server and clients of the client.
Remove packet interval checks with long delays as the tests are much
more likely to end when the client is waiting for a response. Increase
the base delay to make selection with two sources more reliable.
Reported-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>
When authentication is enabled for an NTP source, unauthenticated NTP
sources need to be disabled or limited in selection. That might be
difficult to do when the configuration comes from different sources
(e.g. networking scripts adding servers from DHCP).
Define four modes for the source selection to consider authentication:
require, prefer, mix, ignore. In different modes different selection
options (require, trust, noselect) are added to authenticated and
unauthenticated sources.
The mode can be selected by the authselectmode directive. The mix mode
is the default. The ignore mode enables the old behavior, where all
sources are used exactly as specified in the configuration.
The reset command drops all measurements and switches the reference to
the unsynchronised state. This command can help chronyd with recovery
when the measurements are known to be no longer valid or accurate, e.g.
due to moving the computer to a different network, or resuming the
computer from a low-power state (which resets the system clock).
Add -a option to the sources and sourcestats commands to print all
sources, including those that don't have a resolved address yet. By
default, only sources that have a real address are printed for
compatibility. Remove the "210 Number of sources" messages to avoid
confusion. Also, modify the ntpdata command to always print only sources
with a resolved address.
In the local reference mode, instead of returning the adjusted current
time as the reference time, return the same timestamp updated only once
per about 62.5 seconds.
This will enable chronyd to detect polling of itself even when the local
reference mode is active.
