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opensense-docs/source/manual/ntpd.rst
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==============
Network Time
==============
OPNsense ships with a standard `NTPd <http://doc.ntp.org/current-stable/>`__ server,
which synchronizes time with upstream servers and provides time to connected clients.
A newly installed firewall comes with NTP enabled on all interfaces (firewall blocks all non LAN access in this case),
forwarding queries to one of the :code:`X.opnsense.pool.ntp.org` upstreams (:code:`X` is any of 0,1,2,3).
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General settings
-------------------------
In most cases the default setup is ready to use, below you will find some of the general options which can be configured.
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Interface(s) Interfaces to bind to, when none is selected it listens to all
Time servers Servers to use, comes with two toggles:
* Prefer
Marks the server as preferred.
* Do not use
Marks the server as unused, except for display purposes.
The server is discarded by the selection algorithm.
Orphan mode Orphan mode allows the system clock to be used when no other
clocks are available. The number here specifies the stratum reported
during orphan mode and should normally be set to a number high enough to
insure that any other servers available to clients are
preferred over this server.
NTP graphs Enable RRD graphs of NTP statistics, which can be viewed in
:menuselection:`Reporting --> Health`
Syslog logging Extend logging with peer and/or system messages
Statistics logging Enable statistical logging in :code:`/var/log/ntp`, doesn't come with a
user interface
Access restrictions Within the access restriction row, you can set various options which
limit the use of ntpd and in some cases instruct ntpd how to handle
rejected clients.
Leap seconds You can manually supply ntpd with a leap seconds file, more detailed info
on the contents of those files can be found
`here <http://support.ntp.org/bin/view/Support/ConfiguringNTP#Section_6.14.>`__
==================================== ===============================================================================
.. Note::
NTPs is disabled if no Time servers are configured. There is no separate enable/disable toggle.
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GPS
-------------------------
If you own a gps receiver, which supports NMEA, you can use it as a reference clock and configure it in this section.
For some brands settings are preconfigured, you can also use custom settings.
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PPS
-------------------------
If your GPS receiver supports PPS (Pulse Per Second) output or you have a separate PPS signal available, you
can configure the serial port to use along with some other settings here.
-------------------------
Status
-------------------------
The status page can be used to query the health of the upstream time sources, it shows the following characteristics.
========================================================================================================================
==================================== ==================================================================================
Status Human readable status of the upstream
Server Upstream source
Ref ID Source IP address or
`kiss code: <http://doc.ntp.org/4.2.6p5/decode.html#kiss>`__
Stratum NTP uses a hierarchical, semi-layered system of time sources
(`wikipedia <https://en.wikipedia.org/wiki/Network_Time_Protocol#Clock_strata>`__)
This field shows the stratum of the upstream source
(lower usually means closer to the actual time source)
Type Type of time source, one of:
* u: unicast or manycast client
* b: broadcast or multicast client
* p: pool source
* l: local (reference clock)
* s: symmetric (peer)
* A: manycast server
* B: broadcast server
* M: multicast server
When time in seconds, minutes, hours, or days since the last packet was
received, or '-' if a packet has never been received
Poll poll interval in seconds
Reach reach shift register (octal), when set to :code:`377` all 8 bits are set and thus
no responses have been lost. Convert to bits to inspect which tries failed.
(e.g. :code:`257` --> :code:`10101111` means the last four responses
where received and two where lost within the last 8 tries)
Delay roundtrip delay in milliseconds
Offset offset time in milliseconds of the server relative to this host
Jitter indicates the difference, in milliseconds, between two samples
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