From: Harlan Stenn Date: Thu, 26 Nov 2009 06:16:35 +0000 (-0500) Subject: Documentation changes from Dave Mills X-Git-Tag: NTP_4_2_5P248_RC~4^2 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=54553b6c5139ebd6a01fd1761c5cf0ce46a8a719;p=thirdparty%2Fntp.git Documentation changes from Dave Mills bk: 4b0e1d433rpK5jowK7lOYkzKnHPHkg --- diff --git a/ChangeLog b/ChangeLog index 2e96bac71..60a23adc7 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,4 @@ +* Documentation changes from Dave Mills. * [Bug 1387] Storage leak in ntp_intres (minor). * [Bug 1389] buffer overflow in refclock_oncore.c * [Bug 1391] .texi usage text from installed, not built binaries. diff --git a/html/confopt.html b/html/confopt.html index 6051ced85..05847c2ee 100644 --- a/html/confopt.html +++ b/html/confopt.html @@ -12,7 +12,7 @@ Walt Kelly

The chicken is getting configuration advice.

Last update: - 24-Sep-2009 16:12 + 25-Nov-2009 4:46


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@@ -20,10 +20,10 @@ Walt Kelly

Table of Contents

Following is a description of the configuration commands in NTPv4. There are @@ -52,122 +52,115 @@ Walt Kelly broadcast address [options ...]
manycastclient address [options ...]
pool address [options ...]
- unpeer [address | associd] + unpeer [address | associd]

These commands specify the time server name or address to be used and the mode in which to operate. The address can be either a DNS name or a IPv4 or IPv6 address in standard notation. In general, multiple commands of each type can be used for different server and peer addresses or multicast groups.
-
server +
server
For type s and r addresses (only), this command mobilizes a persistent client mode association with the specified remote server or local reference clock. If the preempt flag is specified, a preemptable client mode - association is mobilized instead. -
peer + association is mobilized instead.
+
peer
For type s addresses (only), this command mobilizes a persistent symmetric-active - mode association with the specified remote peer. -
broadcast + mode association with the specified remote peer. +
broadcast
For type b and m addressees (only), this command mobilizes a persistent broadcast or multicast server mode association. Note that type b messages go only to the interface specified, but type m messages go to - all interfaces. -
manycastclient + all interfaces. +
manycastclient
For type m addresses (only), this command mobilizes a manycast client mode association for the multicast group address specified. In this mode the address must match the address specified on the manycastserver command - of one or more designated manycast servers. -
pool + of one or more designated manycast servers. +
pool
For type s messages (only) this command mobilizes a client mode association for servers implementing the pool automatic server discovery scheme described on the Association Management page. The address is a DNS name in the form area.pool.ntp.org, where area is - a qualifier designating the server geographic area such as us or europe. -
unpeer + a qualifier designating the server geographic area such as us or europe. +
unpeer
This command removes a previously configured association. An address or association ID can be used to identify the association. Either an IP address or DNS name can be used. This command is most useful when supplied via ntpq runtime - configuration commands :config and config-from-file. - + configuration commands :config and config-from-file.
+

Command Options

-
autokey +
autokey
Send and receive packets authenticated by the Autokey scheme described in the Authentication Options page. This option - is mutually exclusive with the key option. -
burst + is mutually exclusive with the key option. +
burst
When the server is reachable, send a burst of eight packets instead of the usual one. The packet spacing is normally 2 s; however, the spacing between the first and second packets can be changed with the calldelay command to allow additional time for a modem or ISDN call to complete. This option is valid only with the server command and type s addressesa. It is a recommended option when the maxpoll option is greater than - 10 (1024 s). -
dynamic -
Allows a server/peer to be configured even if it is not reachable at configuration - time. It is assumed that at some point in the future the network environment - changes so that this server/peer can be reached. This option is useful - to configure servers/peers on mobile systems with intermittent network - access (e.g. WLAN clients). Note: the current implementation does not - support this option. -
iburst + 10 (1024 s). +
iburst
When the server is unreachable, send a burst of eight packets instead of the usual one. The packet spacing is normally 2 s; however, the spacing between the first and second packets can be changed with the calldelay command to allow additional time for a modem or ISDN call to complete. This option is valid only with the server command and type s addresses. It is - a recommended option with this command. -
key key + a recommended option with this command. +
key key
Send and receive packets authenticated by the symmetric key scheme described in the Authentication Options page. The key specifies the key identifier with values from 1 to - 65534, inclusive. This option is mutually exclusive with the autokey option. + 65534, inclusive. This option is mutually exclusive with the autokey option.
minpoll minpoll
- maxpoll maxpoll + maxpoll maxpoll
These options specify the minimum and maximum poll intervals for NTP messages, in seconds as a power of two. The maximum poll interval defaults to 10 (1024 s), but can be increased by the maxpoll option to an upper limit of 17 (36 h). The minimum poll interval defaults to 6 (64 s), but can - be decreased by the minpoll option to a lower limit of 3 (8 s). -
mode option + be decreased by the minpoll option to a lower limit of 3 (8 s). +
mode option
Pass the option to a reference clock driver, where option is an integer in the range from 0 to 255, inclusive. This option is valid - only with type r addresses. -
noselect + only with type r addresses. +
noselect
Marks the server or peer to be ignored by the selection algorithm but visible - to the monitoring program. This option is ignored with the broadcast command. -
preempt + to the monitoring program. This option is ignored with the broadcast command. +
preempt
Specifies the association as preemptable rather than the default persistent. This option is ignored with the broadcast command and is most useful - with the manycastclient and pool commands. -
prefer + with the manycastclient and pool commands. +
prefer
Mark the server as preferred. All other things being equal, this host will be chosen for synchronization among a set of correctly operating hosts. See the Mitigation Rules and the prefer Keyword page - for further information. This option is valid only with the server and peer commands. -
true + for further information. This option is valid only with the server and peer commands. +
true
Mark the association to assume truechimer status; that is, always survive the selection and clustering algorithms. This option can be used with any association, but is most useful for reference clocks with large jitter on the serial port and precision pulse-per-second (PPS) signals. Caution: this option defeats the algorithms designed to cast out falsetickers and can allow these sources - to set the system clock. This option is valid only with the server and peer commands. -
ttl ttl + to set the system clock. This option is valid only with the server and peer commands. +
ttl ttl
This option specifies the time-to-live ttl for the broadcast command and the maximum ttl for the expanding ring search used by the manycastclient command. - Selection of the proper value, which defaults to 127, is something of - a black art and should be coordinated with the network administrator. - This option is invalid with type r addresses.
version version -
Specifies the version number to be used for outgoing NTP packets. Versions - 1-4 are the choices, with version 4 the default. -
xleave + Selection of the proper value, which defaults to 127, is something of a black art and should be coordinated with the network administrator. This option is invalid with type r addresses. +
version version
+
Specifies the version number to be used f +or outgoing NTP packets. Versions + 1-4 are the choices, with version 4 the default.
+
xleave
Operate in interleaved mode (symmetric and broadcast modes only). (see NTP - Interleaved Modes) + Interleaved Modes)

Auxilliary Commands

-
broadcastclient +
broadcastclient
Enable reception of broadcast server messages to any local interface (type b address). Ordinarily, upon receiving a broadcast message for the first time, the broadcast client measures the nominal server propagation delay using @@ -179,14 +172,14 @@ Walt Kelly should operate using symmetric key or public key authentication as described in the Authentication Options page. Note that the novolley keyword is incompatible with - public key authentication. -
manycastserver address [...] + public key authentication. +
manycastserver address [...]
Enable reception of manycast client messages (type m)to the multicast group address(es) (type m) specified. At least one address is required. Note that, in order to avoid accidental or malicious disruption, both the server and client should operate using symmetric key or public key authentication as described - in the Authentication Options page. -
multicastclient address [...] + in the Authentication Options page. +
multicastclient address [...]
Enable reception of multicast server messages to the multicast group address(es) (type m) specified. Upon receiving a message for the first time, the multicast client measures the nominal server propagation delay using a brief client/server @@ -194,7 +187,7 @@ Walt Kelly synchronizes to succeeding multicast messages. Note that, in order to avoid accidental or malicious disruption in this mode, both the server and client should operate using symmetric key or public key authentication as described - in the Authentication Options page. + in the Authentication Options page.

Bugs

The syntax checking is not picky; some combinations of ridiculous and even diff --git a/html/manyopt.html b/html/manyopt.html index ea50a7e89..a236f4fca 100644 --- a/html/manyopt.html +++ b/html/manyopt.html @@ -13,15 +13,17 @@

Automatic Server Discovery

giffrom Alice's Adventures in Wonderland, Lewis Carroll

Make sure who your friends are.

-

Last update: 01:56 UTC Monday, March 17, 2008

-
+

Last update: + 25-Nov-2009 + UTC

+

Related Links

Table of Contents

Introduction

diff --git a/html/quick.html b/html/quick.html index 261094437..8ed31fa8a 100644 --- a/html/quick.html +++ b/html/quick.html @@ -13,15 +13,28 @@

Quick Start

gifFAX test image for SATNET (1979).

The baby panda was scanned at University College London and used as a FAX test image for a demonstration of the DARPA Atlantic SATNET Program and the first transatlantic Internet connection in 1978. The computing system used for that demonstration was called the Fuzzball. As it happened, this was also the first Internet multimedia presentation and the first to use NTP in regular operation. The image was widely copied and used for testing purpose throughout much of the 1980s.

-

Last update: 16:25 UTC Sunday, March 02, 2008

-

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+

Last update: + 25-nov-09 22:13 + UTC

+

Related Links

For the rank amateur the sheer volume of the documentation collection must be intimidating. However, it doesn't take much to fly the ntpd daemon with a simple configuration where a workstation needs to synchronize to some server elsewhere in the Internet. The first thing is to build the distribution for the particular workstation and install in the usual place. The Building and Installing the Distribution page describes how to do this.

While it is possible that certain configurations do not need a configuration file, most do. The file, called by default /etc/ntp.conf, need only contain one command specifying a remote server, for instance

server foo.bar.com

-

Choosing an appropriate remote server is somewhat of a black art, but a suboptimal choice is seldom a problem. There are about two dozen public time servers operated by the National Institutes of Science and Technology (NIST), US Naval Observatory (USNO), Canadian Metrology Centre (CMC) and many others available on the Internet. Lists of public primary and secondary NTP servers maintained on the Public NTP Time Servers page, which is updated frequently.The lists are sorted by country and, in the case of the US, by state. Usually, the best choice is the nearest in geographical terms, but the terms of engagement specified in each list entry should be carefully respected.

-

During operation ntpd measures and corrects for incidental clock frequency error and occasionally writes the current value to a file specified by the

+

Choosing an appropriate remote server is somewhat of a black art, but a + suboptimal choice is seldom a problem. The simplest is to use the + Server Pool Scheme on the Automatic Server Discovery page. There + are about two dozen public time servers operated by the National + Institutes of Science and Technology (NIST), US + Naval Observatory (USNO), Canadian + Metrology Centre (CMC) and many others available on the Internet. Lists + of public primary and secondary NTP servers maintained on the Public + NTP Time Servers page, which is updated frequently.The lists are sorted + by country and, in the case of the US, by state. Usually, the best + choice is the nearest in geographical terms, but the terms of engagement + specified in each list entry should be carefully respected.

+

During operation ntpd measures and corrects for incidental clock frequency error and occasionally writes the current value to a file specified by the

driftfile /etc/ntp.drift

configuration command. If ntpd is stopped and restarted, it initializes the frequency from this file and avoids the potentially lengthy interval to relearn the correction.

That's all there is to it, unless some problem in network connectivity or local operating system configuration occurs. The most common problem is some firewall between the workstation and server. System administrators should understand NTP uses UDP port 123 as both the source and destination port and that NTP does not involve any operating system interaction other than to set the system clock. While almost all modern Unix systems have included NTP and UDP port 123 defined in the services file, this should be checked if ntpd fails to come up at all.