From a499724dbb82dbe7eae50b2c96f4460490ed93bb Mon Sep 17 00:00:00 2001 From: Christian Breunig Date: Sat, 14 Jan 2023 15:30:28 +0100 Subject: T3008: migrate from ntpd to chrony --- docs/configuration/service/ntp.rst | 81 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 81 insertions(+) create mode 100644 docs/configuration/service/ntp.rst (limited to 'docs/configuration/service/ntp.rst') diff --git a/docs/configuration/service/ntp.rst b/docs/configuration/service/ntp.rst new file mode 100644 index 00000000..5b718c4f --- /dev/null +++ b/docs/configuration/service/ntp.rst @@ -0,0 +1,81 @@ +.. _ntp: + +### +NTP +### + +:abbr:`NTP (Network Time Protocol`) is a networking protocol for clock +synchronization between computer systems over packet-switched, variable-latency +data networks. In operation since before 1985, NTP is one of the oldest Internet +protocols in current use. + +NTP is intended to synchronize all participating computers to within a few +milliseconds of :abbr:`UTC (Coordinated Universal Time)`. It uses the +intersection algorithm, a modified version of Marzullo's algorithm, to select +accurate time servers and is designed to mitigate the effects of variable +network latency. NTP can usually maintain time to within tens of milliseconds +over the public Internet, and can achieve better than one millisecond accuracy +in local area networks under ideal conditions. Asymmetric routes and network +congestion can cause errors of 100 ms or more. + +The protocol is usually described in terms of a client-server model, but can as +easily be used in peer-to-peer relationships where both peers consider the other +to be a potential time source. Implementations send and receive timestamps using +:abbr:`UDP (User Datagram Protocol)` on port number 123. + +NTP supplies a warning of any impending leap second adjustment, but no +information about local time zones or daylight saving time is transmitted. + +The current protocol is version 4 (NTPv4), which is a proposed standard as +documented in :rfc:`5905`. It is backward compatible with version 3, specified +in :rfc:`1305`. + +.. note:: VyOS 1.4 uses chrony instead of ntpd (see :vytask:`T3008`) which will + no longer accept anonymous NTP requests as in VyOS 1.3. All configurations + will be migrated to keep the anonymous functionality. For new setups if you + have clients using your VyOS installation as NTP server, you must specify + the `allow-client` directive. + +Configuration +============= + +.. cfgcmd:: set service ntp server
+ + Configure one or more servers for synchronisation. Server name can be either + an IP address or :abbr:`FQDN (Fully Qualified Domain Name)`. + + There are 3 default NTP server set. You are able to change them. + + * ``0.pool.ntp.org`` + * ``1.pool.ntp.org`` + * ``2.pool.ntp.org`` + +.. cfgcmd:: set service ntp server
+ + Configure one or more attributes to the given NTP server. + + * ``noselect`` marks the server as unused, except for display purposes. The + server is discarded by the selection algorithm. + + * ``pool`` mobilizes persistent client mode association with a number of + remote servers. + + * ``prefer`` marks the server as preferred. All other things being equal, + this host will be chosen for synchronization among a set of correctly + operating hosts. + +.. cfgcmd:: set service ntp listen-address
+ + NTP process will only listen on the specified IP address. You must specify + the `
` and optionally the permitted clients. Multiple listen + addresses can be configured. + +.. cfgcmd:: set service ntp allow-client address
+ + List of networks or client addresses permitted to contact this NTP server. + + Multiple networks/client IP addresses can be configured. + +.. cfgcmd:: set service ntp vrf + + Specify name of the :abbr:`VRF (Virtual Routing and Forwarding)` instance. -- cgit v1.2.3