ntpq- standard NTP query program
ntpq [ -inp ] [ -c command ] [ host ] [ ... ]
ntpq is used to query NTP servers which implement the
recommended NTP mode 6 control message format about current state and to
request changes in that state. The program may be run either in
interactive mode or controlled using command line arguments. Requests to
read and write arbitrary variables can be assembled, with raw and
pretty-printed output options being available.
also obtain and print a list of peers in a common format by sending
multiple queries to the server.
If one or more request options is included on the command line when
ntpq is executed, each of the requests will be sent to the
NTP servers running on each of the hosts given as command line
arguments, or on localhost by default. If no request options are given,
ntpq will attempt to read commands from the standard input
and execute these on the NTP server running on the first host given on
the command line, again defaulting to localhost when no other host is
ntpq will prompt for commands if the standard
input is a terminal device.
ntpq uses NTP mode 6 packets to communicate with the NTP
server, and hence can be used to query any compatable server on the
network which permits it. Note that since NTP is a UDP protocol this
communication will be somewhat unreliable, especially over large
distances in terms of network topology.
ntpq makes one
attempt to retransmit requests, and will time requests out if the remote
host is not heard from within a suitable timeout time.
Command line options are described following. Specifying a command
line option other than -i or -n will cause the specified query (queries)
to be sent to the indicated host(s) immediately. Otherwise,
ntpq will attempt to read interactive format commands from
the standard input.
ntpqto operate in interactive mode. Prompts will be written to the standard output and commands read from the standard input.
Interactive format commands consist of a keyword followed by zero to
four arguments. Only enough characters of the full keyword to uniquely
identify the command need be typed. The output of a command is normally
sent to the standard output, but optionally the output of individual
commands may be sent to a file by appending a "<", followed by a file
name, to the command line. A number of interactive format commands are
executed entirely within the
ntpq program itself and do not
result in NTP mode 6 requests being sent to a server. These are
? [ command_keyword ]
"?"by itself will print a list of all the command keywords known to this incarnation of
"?"followed by a command keyword will print funcation and usage information about the command. This command is probably a better source of information about
ntpqthan this manual page.
addvars variable_name [ = value ] [ ... ]
rmvars variable_name [ ... ]
variable_name = value, where the
" = value"is ignored, and can be omitted, in requests to the server to read variables.
ntpqmaintains an internal list in which data to be included in control messages can be assembled, and sent using 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 not contain white space. The rmvars command can be used to remove individual variables from the list, while the clearlist command removes all variables from the list.
authenticate yes | no
ntpqdoes not authenticate requests unless they are write requests. The command authenticate yes causes
ntpqto send authentication with all requests it makes. Authenticated requests causes some servers to handle requests slightly differently, and can occasionally melt the CPU in fuzzballs if you turn authentication on before doing a peer display.
"cooked". Variables which are recognized by the server will have their values reformatted for human consumption. Variables which
ntpqthinks should have a decodeable value but didn't are marked with a trailing
debug more | less | off
hostnames [ yes | no ]
"yes"is specified, host names are printed in information displays. If
"no"is specified, numeric addresses are printed instead. The default is
"yes", unless modified using the command line
ntpversion 1 | 2 | 3
ntpqclaims in packets. Defaults to 3, Note that mode 6 control messages (and modes, for that matter) didn't exist in NTP version 1. There appear to be no servers left which demand version 1.
ntpqretries each query once after a timeout, the total waiting time for a timeout will be twice the timeout value set.
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 the values correspond to by including its association ID. An association ID of 0 is special, and indicates the variables are system variables, whose names are drawn from a separate name space.
Control message commands result in one or more NTP mode 6 messages being sent 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 command, which will send a preprogrammed series of messages to obtain the data it needs, and the mreadlist and mreadvar commands, which will iterate over a range of associations.
"associations"command is cached internally in
ntpq. The index is then of use when dealing with stupid servers which use association identifiers which are hard for humans to type, in that for any subsequent commands which require an association identifier as an argument, the form &index may be used as an alternative.
clockvar [ assocID ] [ variable_name [ =
cv [ assocID ] [ variable_name [ = value [ ... ]] [ ... ]
"system clock"and will generally get a positive response from all servers with a clock. If the server treats clocks as pseudo-peers, and hence can possibly have more than one clock connected at once, referencing the appropriate peer association ID will show the variables of a particular clock. Omitting the variable list will cause the server to return a default variable display.
"associations"command only for servers which retain state for out-of-spec client associations (i.e., fuzzballs). Such associations are normally omitted from the display when the
"associations"command is used, but are included in the output of
"passociations"only when dealing with fuzzballs.
mreadlist assocID assocID
mrl assocID assocID
readlistcommand, 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
mreadvar assocID assocID [ variable_name [ = value [ ... ]
mrv assocID assocID [ variable_name [ = value [ ... ]
readvarcommand, 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
peerscommand with the reference ID replaced by the local interface address.
"associations"except that it displays the internally stored data rather than making a new query.
"x"designated falsticker by the intersection algorithm;
"."culled from the end of the candidate list;
"-"discarded by the clustering algorithmi;
"+"included in the final selection set;
"#"selected for synchronizatio;n but distance exceeds maximum;
"*"selected for synchronization; and
"o"selected for synchronization, PPS signal in use.
"hostnames no"only IP-addresses will be displayed.
readlist [ assocID ]
rl [ assocID ]
readvar assocID variable_name [ = value ] [ ... ]
rv assocID [ variable_name [ = value ] [ ... ]
writevar assocID variable_name [ = value [ ... ]
writelist [ assocID ]
The peers command is non-atomic and may occasionally result in spurious error messages about invalid associations occurring and terminating the command. The timeout time is a fixed constant, which means you wait a long time for timeouts since it assumes sort of a worst case. The program should improve the timeout estimate as it sends queries to a particular host, but doesn't.