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121 lines
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121 lines
7.4 KiB
ReStructuredText
==============
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Network Time
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==============
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OPNsense ships with a standard `NTPd <http://doc.ntp.org/current-stable/>`__ server,
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which synchronizes time with upstream servers and provides time to connected clients.
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A newly installed firewall comes with NTP enabled on all interfaces (firewall blocks all non LAN access in this case),
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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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-------------------------
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General settings
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-------------------------
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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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=====================================================================================================================
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.. Attention::
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NTPd syncs the local clock to remote NTP servers and listens for incoming client queries using the selected interfaces.
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The interface selection must therefore include a WAN type interface so that normal routing to the internet can take place.
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Only selecting a LAN type interface will likely work due to outbound NAT rules, however, if CARP is configured, it is
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possible that such NAT rules will translate to the address of the CARP VIP, causing asymmetric routing for secondary nodes.
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Unless you are sure that you want to use a specific interface, it is recommended to keep the default of listening
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on all interfaces and use the firewall rules to constrain access to the NTP service.
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See `Listen interfaces <settingsmenu.html#listen-interfaces>`__ for more information.
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==================================== ===============================================================================
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Interface(s) Interfaces to listen on. This interface selection is also used for outgoing
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queries. when no interfaces are selected it listens on all interfaces with a
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wildcard. Selecting all interfaces will explicitly listen on only the
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interfaces/IPs specified. Interfaces without an IP address will not be shown.
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Time servers Servers to use, comes with two toggles:
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* Prefer
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Marks the server as preferred.
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* Do not use
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Marks the server as unused, except for display purposes.
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The server is discarded by the selection algorithm.
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Orphan mode Orphan mode allows the system clock to be used when no other
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clocks are available. The number here specifies the stratum reported
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during orphan mode and should normally be set to a number high enough to
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insure that any other servers available to clients are
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preferred over this server.
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NTP graphs Enable RRD graphs of NTP statistics, which can be viewed in
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:menuselection:`Reporting --> Health`
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Syslog logging Extend logging with peer and/or system messages
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Statistics logging Enable statistical logging in :code:`/var/log/ntp`, doesn't come with a
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user interface
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Access restrictions Within the access restriction row, you can set various options which
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limit the use of ntpd and in some cases instruct ntpd how to handle
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rejected clients.
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Leap seconds You can manually supply ntpd with a leap seconds file, more detailed info
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on the contents of those files can be found
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`here <http://support.ntp.org/bin/view/Support/ConfiguringNTP#Section_6.14.>`__
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==================================== ===============================================================================
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.. Note::
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NTPs is disabled if no Time servers are configured. There is no separate enable/disable toggle.
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-------------------------
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GPS
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-------------------------
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If you own a gps receiver, which supports NMEA, you can use it as a reference clock and configure it in this section.
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For some brands settings are preconfigured, you can also use custom settings.
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-------------------------
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PPS
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-------------------------
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If your GPS receiver supports PPS (Pulse Per Second) output or you have a separate PPS signal available, you
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can configure the serial port to use along with some other settings here.
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-------------------------
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Status
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-------------------------
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The status page can be used to query the health of the upstream time sources, it shows the following characteristics.
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========================================================================================================================
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==================================== ==================================================================================
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Status Human readable status of the upstream
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Server Upstream source
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Ref ID Source IP address or
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`kiss code: <http://doc.ntp.org/4.2.6p5/decode.html#kiss>`__
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Stratum NTP uses a hierarchical, semi-layered system of time sources
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(`wikipedia <https://en.wikipedia.org/wiki/Network_Time_Protocol#Clock_strata>`__)
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This field shows the stratum of the upstream source
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(lower usually means closer to the actual time source)
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Type Type of time source, one of:
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* u: unicast or manycast client
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* b: broadcast or multicast client
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* p: pool source
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* l: local (reference clock)
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* s: symmetric (peer)
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* A: manycast server
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* B: broadcast server
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* M: multicast server
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When time in seconds, minutes, hours, or days since the last packet was
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received, or '-' if a packet has never been received
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Poll poll interval in seconds
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Reach reach shift register (octal), when set to :code:`377` all 8 bits are set and thus
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no responses have been lost. Convert to bits to inspect which tries failed.
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(e.g. :code:`257` --> :code:`10101111` means the last four responses
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where received and two where lost within the last 8 tries)
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Delay roundtrip delay in milliseconds
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Offset offset time in milliseconds of the server relative to this host
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Jitter indicates the difference, in milliseconds, between two samples
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==================================== ==================================================================================
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