Content-type: text/html Man page of ntpq


Section: System Administration Commands (1M)
Updated: 12 July 2004
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ntpq - standard Network Time Protocol query program  


/usr/sbin/ntpq [-inp] [-c command] [host] [...]  


ntpq queries NTP servers which implement the recommended NTP mode 6 control message format, about current state. It can also request changes in that state. The program can be run in interactive mode; or it can be controlled using command line arguments. Requests to read and write arbitrary variables can be assembled, with raw and pretty-printed output options available. By sending multiple queries to the server, ntpq can also obtain and print a list of peers in a common format.

If one or more request options are included on the command line, ntpq sends each of the requests to NTP servers running on each of the hosts given as command line arguments. By default, ntpq sends its requests to localhost, if hosts are not included on the command line. If no request options are given, ntpq attempts to read commands from the standard input and execute them on the NTP server running on the first host given on the command line. Again, ntpq defaults to localhost if no other host is specified.

ntpq uses NTP mode 6 packets to communicate with an NTP server. Thus, it can be used to query any compatible server on the network that permits queries. Since NTP is a UDP protocol, this communication will be somewhat unreliable, especially over large distances. ntpq makes one attempt to retransmit requests; requests timeout if the remote host is not heard from within a suitable period.  


Command line options are described below. Specifying a command line option other than -i or -n causes the specified query (queries) to be sent, immediately to the indicated host(s). Otherwise, ntpq attempts to read interactive format commands from standard input.

-c Interpret the next argument as an interactive format command and add it to the list of commands to be executed on the specified host(s). Multiple -c options may be given.

-i Operate in interactive mode; write prompts to standard output and read commands from standard input.

-n Output all host addresses in dotted-quad numeric format rather than converting them to canonical host names.

-p Print a list of the peers known to the server as well as a summary of their state. This is equivalent to the peers interactive command. See USAGE below.



Interactive format commands consist of a keyword followed by up to four arguments. Only enough characters of the full keyword to uniquely identify the command need be typed. Normally, the output of a command is sent to standard output; but this output may be written to a file by appending a `>', followed by a file name, to the command line.  

Interactive Commands

A number of interactive format commands are executed entirely within the ntpq program itself. They do not result in NTP mode 6 requests being sent to a server. If no request options are included on the command line, and if the standard input is a terminal device, ntpq prompts for these commands. The interactive commands are described below:

? [command_keyword]

A `?' by itself prints a list of all the command keywords known to the current version of ntpq. A `?' followed by a command keyword prints function and usage information about the command.


Specifies a time out period for responses to server queries. The default is about 5000 milliseconds. Since ntpq retries each query once after a time out, the total waiting time for a time out is twice the time out value that is set.


Specifies a time interval to be added to timestamps included in requests which require authentication. This command is used to enable (unreliable) server reconfiguration over long delay network paths or between machines whose clocks are unsynchronized. Currently, the server does not require time stamps in authenticated requests. Thus, this command may be obsolete.


Set the name of the host to which future queries are to be sent. Hostname may be either a host name or a numeric address.

keyid #

Specify of a key number to be used to authenticate configuration requests. This number must correspond to a key number the server has been configured to use for this purpose.


Allow the user to specify a password at the command line. This will be used to authenticate configuration requests. If an authenticating key has been specified (see keyid above), this password must correspond to this key. ntpq does not echo the password as it is typed.

hostnames yes|no

If "yes" is specified, host names are printed in information displays. If "no" is given, numeric addresses are printed instead. The default is "yes" unless modified using the command line -n switch.


Print all output from query commands exactly as it is received from the remote server. The only formatting/filtering done on the data is to transform non- ASCII data into printable form.


Causes output from query commands to be "cooked". The values of variables recognized by the server are reformatted, so that they can be more easily read. Variables which ntpq thinks should have a decodable value, but do not, are marked with a trailing `?'.

ntpversion[ 1|2|3 ]

Sets the NTP version number which ntpq claims in packets (defaults is 3). Note that mode 6 control messages (and modes, for that matter) did not exist in NTP version 1. There appear to be no servers left which demand version 1.

authenticate[ yes|no ]

The command authenticate yes instructs ntpq to send authentication with all requests it makes. Normally ntpq does not authenticate requests unless they are write requests. Authenticated requests cause some servers to handle requests slightly differently, and can occasionally cause a slowed response if you turn authentication on before doing a peer display. addvars variable_name[=value] [ ,... ] rmvars variable_name [ ,... ] clearvars

The data carried by NTP mode 6 messages consists of a list of items of the form


where the "=value" is ignored, and can be omitted, in requests to the server to read variables. ntpq maintains an internal list in which data to be included in control messages can be assembled, and sent. This is accomplished with the readlist and writelist commands described below. The addvars command allows variables and their optional values to be added to the list. If more than one variable is to be added, the list should be comma-separated, and it should not contain white space. The rmvars command can be used to remove individual variables from the list; the clearlist command removes all variables from the list.

debug[ more|less|off ]

Turns internal query program debugging on and off.


Exit ntpq.


Control Message Commands

Each peer known to an
 NTP server has a 16 bit integer association identifier assigned to it. NTP control messages which carry peer variables must identify the peer that the values correspond to, by including its association ID. An association ID of 0 is special. It indicates the variables are system variables, whose names are drawn from a separate name space.

Control message commands send one or more NTP mode 6 messages to the server, and cause the data returned to be printed in some format. Most commands currently implemented send a single message and expect a single response. The current exceptions are the peers mreadlist and mreadvar commands. The peers command sends a preprogrammed series of messages to obtain the data it needs. The mreadlist and mreadvar commands, iterate over a range of associations.

Control message commands are described below:


Obtains and prints a list of association identifiers and peer statuses for in-spec peers of the server being queried. The list is printed in columns. The first of these is an index that numbers the associations from 1, for internal use. The second column contains the actual association identifier returned by the server and the third the status word for the peer. This is followed by a number of columns containing data decoded from the status word. Note that the data returned by the associations command is cached internally in ntpq. The index is then of use when dealing with "dumb" servers which use association identifiers that are hard for humans to type. For any subsequent commands which require an association identifier as an argument, the identifier can be specified by using the form, &index. Here index is taken from the previous list.


Obtains and prints a list of association identifiers and peer statuses for all associations for which the server is maintaining state. This command differs from the associations command only for servers which retain state for out-of-spec client associations. Such associations are normally omitted from the display when the associations command is used, but are included in the output of lassociations.


Prints association data concerning in-spec peers from the internally cached list of associations. This command performs identically to the associations command except that it displays the internally stored data rather than making a new query.


Print data for all associations, including out-of-spec client associations, from the internally cached list of associations. This command differs from
 passociations only when dealing with servers which retain
 state for out-of-spec client associations.


Sends a read status request to the server for the given association. The names and values of the peer variables returned will be printed. Note that the status word from the header is displayed preceding the variables, both in hexadecimal and in pigeon English.

readvar [ assoc] [ variable_name[=value][ ,... ]]

Requests that the values of the specified variables be returned by the server by sending a read variables request. If the association ID is omitted or is given as zero the variables are system variables, otherwise they are peer variables and the values returned will be those of the corresponding peer. Omitting the variable list will send a request with no data which should induce the server to return a default display.

rv [ assocID] [ variable_name[=value][ ,... ]]

An easy-to-type short form for the readvar command.

writevar assocID variable_name=value [ ,... ]

Like the readvar request, except the specified variables are written instead of read.

readlist [ assocID]

Requests that the values of the variables in the internal variable list be returned by the server. If the association ID is omitted or is 0 the variables are assumed to be system variables. Otherwise they are treated as peer variables. If the internal variable list is empty a request is sent without data, which should induce the remote server to return a default display.

rl [ assocID]

An easy-to-type short form of the readlist command.

writelist [ assocID]

Like the readlist request, except the internal list variables are written instead of read.

mreadvar assocID assocID [ variable_name[=value] [ ,... ]]

Like the readvar command except the query is done for each of a range of (nonzero) association IDs. This range is determined from the association list cached by the most recent associations command.

mrv assocID assocID [ variable_name[=value] [ ,... ]]

An easy-to-type short form of the mreadvar command.

mreadlistassocID assocID

Like the readlist command except the query is done for each of a range of (nonzero) association IDs. This range is determined from the association list cached by the most recent associations command.

mrlassocID assocID

An easy-to-type short form of the mreadlist command.

clockvar [ assocID] [ variable_name[=value][ ,... ]]

Requests that a list of the server's clock variables be sent. Servers which have a radio clock or other external synchronization respond positively to this. If the association identifier is omitted or zero the request is for the variables of the "system clock". This request generally gets a positive response from all servers with a clock. Some servers may treat clocks as pseudo-peers and, hence, can possibly have more than one clock connected at once. For these servers, referencing the appropriate peer association ID shows the variables of a particular clock. Omitting the variable list causes the server to return a default variable display.

cv [ assocID] [ variable_name[=value][ ,... ]]

An easy-to-type short form of the clockvar command.


Obtains a list of in-spec peers of the server, along with a summary of each peer's state. Summary information includes:

• The address of the remote peer

• The reference ID ( if the ref ID is unknown)

• The stratum of the remote peer

• The type of the peer (local, unicast, multicast or broadcast) when the last packet was received

• The polling interval in seconds

• The reachability register, in octal

• The current estimated delay offset and dispersion of the peer, all in milliseconds.

The character in the left margin indicates the fate of this peer in the clock selection process. The codes mean:

SPACE Discarded due to high stratum and/or failed sanity checks.

x Designated falsticker by the intersection algorithm.

. Culled from the end of the candidate list.

- Discarded by the clustering algorithm.

+ Included in the final selection set.

# Selected for synchronization; but distance exceeds maximum.

* Selected for synchronization.

o Selected for synchronization, pps signal in use.

Since the peers command depends on the ability to parse the values in the responses it gets, it may fail to work from time to time with servers which poorly control the data formats.

The contents of the host field may be given in one of four forms. It may be a host name, an IP address, a reference clock implementation name with its parameter or, REFCLK(implementation number, parameter). On "hostnames no" only IP-addresses will be displayed.


Like peers, except a summary of all associations for which the server is maintaining state is printed. This can produce a much longer list of peers from inadequate servers.


An old form of the peers command with the reference ID replaced by the local interface address.



See attributes(5) for descriptions of the following attributes:






The peers command is non-atomic. It may occasionally result in spurious error messages about invalid associations occurring and terminating the command.

The timeout value is a fixed constant. As a result, it often waits a long time to timeout, since the fixed value assumes sort of a worst case. The program should improve the time out estimate as it sends queries to a particular host; but it does not.



Interactive Commands
Control Message Commands

This document was created by man2html, using the manual pages.
Time: 02:37:11 GMT, October 02, 2010