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OPT_CHRONY extends fli4l with the Network Time
Protocol (NTP). Don't mix it up with the normal Time Protocol,
the old OPT_TIME provides. The protocols aren't compatible wich possibly raises the need
of new client-side programs, which understand NTP. If you can't abandon the
simple time protocol, chrony can provide it as well.
OPT_CHRONY works both as a server and client. Working as a client, OPT_CHRONY
adjusts the time of the fli4l according to time referencies (time servers) in
the internet. The basic setting uses up to three time servers from
pool.ntp.org. However it's possible to use a different
selection of time servers in the configuration file. Thus it's possible to use time servers
near you, if you choose de.pool.ntp.org if the router or your provider sits in Germany.
For more details, look at the website of pool.ntp.org.
Working as a client, OPT_CHRONY acts as a time reference for the local network (LAN). NTP uses port 123.
Chrony doesn't need a permanent connection to the internet. When the connection drops, chrony get's a notice and ceases the adjustion with the internet time servers. Neither does chrony dial to raise the connection nor prevent the automatic hangup, if HUP_TIMEOUT, the duration where no data is routet to the internet, is reached.
In order to do time adjustments smoothly, the following should be in mind:
Only time servers in the internet which are reachable by the default route (0.0.0.0/0) can be used, because only the default route changes chrony into online mode. As an ethernet router with no DSL or ISDN circuits configured, chrony acts permanently in online mode.
Disclaimer: The author gives neither a guarantee of functionality nor is he liable for any damage or the loss of data when using OPT_CHRONY.
The configuration is made, as for all fli4l packages, by adjusting the file
path/fli4l-3.10.17/<config>/chrony.txt to meet the own demands.
However almost all variables of OPT_CHRONY are optional. Optional means, the
variables could, but need not be in the config file.
Thus the chrony config file is almost empty and all optional
variables have a usefull setting by default.
To use different settings, the variables must be inserted into the config file
by hand. Furthermore the description of every variable follows:
Default: OPT_CHRONY='no'
The setting 'no' deactivates OPT_CHRONY completely. There will be no changes
made on the fli4l boot medium or the archive opt.img.
Further OPT_CHRONY basically does not overwrite other parts of the fli4l installation
with one exception. The paket filter file which is responsible for not counting the
traffic coming from the outside (to make sure fli4l will drop the line for sure,
when reaching the hangup time), will be exchanged. The new paket filter file ensures,
that chrony-traffic doesn't count for the hangup time.
To activate OPT_CHRONY, the variable OPT_CHRONY has to be set to 'yes'.
Default: CHRONY_TIMESERVICE='no'
With CHRONY_TIMESERVICE an additional protocol to transfer time informations can be invoked. It's only neccesary when the local hosts can't deal with NTP. It is conform to RFC 868 and uses port 37. If possible, prefer NTP.
Many thanks to Christoph Schulz, who provided the program srv868.
Default: CHRONY_TIMESERVER_N='3'
CHRONY_TIMESERVER_N sets the number of reference time servers chrony uses.
Add the same number of CHRONY_TIMESERVER_x variables. The index x
must be increased up to the total number.
The basic setting uses up to three time servers from
pool.ntp.org.
Default: CHRONY_TIMESERVER_x='pool.ntp.org'
With CHRONY_TIMESERVER_x an own list of internet time servers can be made. Either IP or DNS hostnames are possible.
Default: CHRONY_LOG='/var/run'
CHRONY_LOG is the folder where chrony stores informations about the BIOS clock and the time adjustments. In almost any cases, this should not be altered.
Default: CHRONY_BIOS_TIME='utc'
To analyze the time of the BIOS clock (RTC = real time clock) correctly, CHRONY_BIOS_TIME provides if the clock runs at local 'local' or universal time 'utc' (UTC - Universal Coordinated Time).
Homepage of chrony: http://chrony.tuxfamily.org/
NTP: The Network Time Protocol: http://www.ntp.org/
pool.ntp.org: public ntp time server for everyone: http://www.pool.ntp.org/en/
RFC 1305 - Network Time Protocol (Version 3) Specification, Implementation:
http://www.faqs.org/rfcs/rfc1305.html
fli4l Newsgroups and the rules: http://www.fli4l.de/hilfe/newsgruppen/