ntpq - standard NTP query program

Last update: March 27, 2023 22:34 UTC (39505daf6)


from Pogo, Walt Kelly

A typical NTP monitoring packet

Table of Contents


ntpq [-46dinp] [-c command] [host] […]


The ntpq utility program is used to monitor NTP daemon ntpd operations and determine performance. It uses the standard NTP mode 6 control message formats defined in Appendix B of the NTPv3 specification RFC 1305. The same formats are used in NTPv4, although some of the variable names have changed and new ones added. The description on this page is for the NTPv4 variables.

The program can 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. The ntpq can 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 specified. 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 compatible 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.

Note that in contexts where a host name is expected, a -4 qualifier preceding the host name forces DNS resolution to the IPv4 namespace, while a -6 qualifier forces DNS resolution to the IPv6 namespace.

For examples and usage, see the NTP Debugging Techniques page.

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.

Force DNS resolution of following host names on the command line to the IPv4 namespace.
Force DNS resolution of following host names on the command line to the IPv6 namespace.
The following argument is interpreted as an interactive format command and is added to the list of commands to be executed on the specified host(s). Multiple -c options may be given.
Turn on debugging mode.
Force ntpq to operate in interactive mode. Prompts will be written to the standard output and commands read from the standard input.
Output all host addresses in dotted-quad numeric format rather than converting to the canonical host names.

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.

Internal Commands

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 described following.

? [command_keyword]
help [command_keyword]
A ? by itself will print a list of all the command keywords known to ntpq. A ? followed by a command keyword will print function and usage information about the command.
addvars name [ = value] […]
rmvars name […]
The arguments to this command consist of a list of items of the form name = value, where the = value is ignored, and can be omitted in read requests. ntpq maintains 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 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.
Display server messages in prettyprint format.
debug more | less | off
Turns internal query program debugging on and off.
delay milliseconds
Specify a time interval to be added to timestamps included in requests which require authentication. This is used to enable (unreliable) server reconfiguration over long delay network paths or between machines whose clocks are unsynchronized. Actually the server does not now require timestamps in authenticated requests, so this command may be obsolete.
host name
Set the host to which future queries will be sent. The name may be either a DNS name or a numeric address.
hostnames [yes | no]
If 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 -n switch.
keyid keyid
This command specifies the key number to be used to authenticate configuration requests. This must correspond to a key ID configured in ntp.conf for this purpose.
Specify the digest algorithm to use for authenticated requests, with default MD5. If the OpenSSL library is installed, digest can be any message digest algorithm supported by the library. The current selections are: MD2, MD4, MD5, MDC2, RIPEMD160, SHA, SHA1, and AES128CMAC.
ntpversion 1 | 2 | 3 | 4
Sets the NTP version number which ntpq claims in packets. Defaults to 2, Note that mode-6 control messages (and modes, for that matter) didn’t exist in NTP version 1.
This command prompts for a password to authenticate requests. The password must correspond to the key ID configured in ntp.conf for this purpose.
Exit ntpq.
Display server messages as received and without reformatting.
timeout millseconds
Specify a timeout period for responses to server queries. The default is about 5000 milliseconds. Note that since ntpq retries each query once after a timeout, the total waiting time for a timeout will be twice the timeout value set.

Control Message Commands

Association IDs are used to identify system, peer and clock variables. System variables are assigned an association ID of zero and system name space, while each association is assigned a nonzero association ID and peer namespace. Most control commands send a single mode-6 message to the server and expect a single response message. The exceptions are the peers command, which sends a series of messages, and the mreadlist and mreadvar commands, which iterate over a range of associations.

Display a list of mobilized associations in the form

ind assid status conf reach auth condition last_event cnt

Variable Description
ind index on this list
assid association ID
status peer status word
conf yes: persistent
no: ephemeral
reach yes: reachable
no: unreachable
auth ok, yes, bad and none
condition selection status (see the select field of the peer status word)
last_event event report (see the event field of the peer status word)
cnt event count (see the count field of the peer status word)
clockvar assocID [name [ = value […]] […]
cv assocID [name [ = value […] ][…]
Display a list of clock variables for those associations supporting a reference clock.
:config […]
Send the remainder of the command line, including whitespace, to the server as a run-time configuration command in the same format as the configuration file. This command is experimental until further notice and clarification. Authentication is of course required.
config-from-file filename
Send each line of filename to the server as run-time configuration commands in the same format as the configuration file. This command is experimental until further notice and clarification. Authentication is required.
Display statistics for each local network address. Authentication is required.
Display network and reference clock I/O statistics.
Display kernel loop and PPS statistics. As with other ntpq output, times are in milliseconds. The precision value displayed is in milliseconds as well, unlike the precision system variable.
Perform the same function as the associations command, except display mobilized and unmobilized associations.
Display monitor facility statistics.
mrulist [limited | kod | mincount=count | laddr=localaddr | sort=sortorder | resany=hexmask | resall=hexmask]
Obtain and print traffic counts collected and maintained by the monitor facility. With the exception of sort=sortorder, the options filter the list returned by ntpd. The limited and kod options return only entries representing client addresses from which the last packet received triggered either discarding or a KoD response. The mincount=count option filters entries representing less than count packets. The laddr=localaddr option filters entries for packets received on any local address other than localaddr. resany=hexmask and resall=hexmask filter entries containing none or less than all, respectively, of the bits in hexmask, which must begin with 0x.

The sortorder defaults to lstint and may be any of addr, count, avgint, lstint, or any of those preceded by a minus sign (hyphen) to reverse the sort order. The output columns are:

Column Description
lstint Interval in s between the receipt of the most recent packet from this address and the completion of the retrieval of the MRU list by ntpq.
avgint Average interval in s between packets from this address.
rstr Restriction flags associated with this address. Most are copied unchanged from the matching restrict command, however 0x400 (kod) and 0x20 (limited) flags are cleared unless the last packet from this address triggered a rate control response.
r Rate control indicator, either a period, L or K for no rate control response, rate limiting by discarding, or rate limiting with a KoD response, respectively.
m Packet mode.
v Packet version number.
count Packets received from this address.
rport Source port of last packet from this address.
remote address DNS name, numeric address, or address followed by claimed DNS name which could not be verified in parentheses.
mreadvar assocID assocID [ variable_name [ = value[ … ]
mrv assocID assocID [ variable_name [ = value[ … ]
Perform the same function as the readvar command, except for a range of association IDs. This range is determined from the association list cached by the most recent associations command.
Perform the same function as the associations command, except that it uses previously stored data rather than making a new query.
Display a list of peers in the form

[tally]remote refid st t when pool reach delay offset jitter

Variable Description
[tally] single-character code indicating current value of the select field of the peer status word
remote host name (or IP number) of peer
refid association ID or kiss code
st stratum
t u: unicast or manycast client
b: broadcast or multicast client
p: pool source
l: local (reference clock)
s: symmetric (peer)
A: manycast server
B: broadcast server
M: multicast server
when sec/min/hr since last received packet
poll poll interval (log2 s)
reach reach shift register (octal)
delay roundtrip delay
offset offset of server relative to this host
jitter jitter
readvar assocID name [ = value ] [,…]
rv assocID [ name ] [,…]
Display the specified variables. If assocID is zero, the variables are from the system variables name space, otherwise they are from the peer variables name space. The assocID is required, as the same name can occur in both spaces. If no name is included, all operative variables in the name space are displayed. In this case only, if the assocID is omitted, it is assumed zero. Multiple names are specified with comma separators and without whitespace. Note that time values are represented in milliseconds and frequency values in parts-per-million (PPM). Some NTP timestamps are represented in the format YYYYMMDDTTTT, where YYYY is the year, MM the month of year, DD the day of month and TTTT the time of day.
saveconfig filename
Write the current configuration, including any runtime modifications given with :config or config-from-file, to the ntpd host’s file filename. This command will be rejected by the server unless saveconfigdir appears in the ntpd configuration file. filename can use strftime() format specifies to substitute the current date and time, for example, saveconfig ntp-%Y%m%d-%H%M%S.conf. The filename used is stored in system variable savedconfig. Authentication is required.
writevar assocID name = value [,…]
Write the specified variables. If the assocID is zero, the variables are from the system variables name space, otherwise they are from the peer variables name space. The assocID is required, as the same name can occur in both spaces.
Display operational summary.
Print statistics counters maintained in the protocol module.

Status Words and Kiss Codes

The current state of the operating program is shown in a set of status words maintained by the system and each association separately. These words are displayed in the rv and as commands both in hexadecimal and decoded short tip strings. The codes, tips and short explanations are on the Event Messages and Status Words page. The page also includes a list of system and peer messages, the code for the latest of which is included in the status word.

Information resulting from protocol machine state transitions is displayed using an informal set of ASCII strings called kiss codes. The original purpose was for kiss-o'-death (KoD) packets sent by the server to advise the client of an unusual condition. They are now displayed, when appropriate, in the reference identifier field in various billboards.

System Variables

The following system variables appear in the rv billboard. Not all variables are displayed in some configurations.

Variable Description
status system status word
version NTP software version and build time
processor hardware platform and version
system operating system and version
leap leap warning indicator (0-3)
stratum stratum (1-15)
precision precision (log2 s)
rootdelay total roundtrip delay to the primary reference clock
rootdisp total dispersion to the primary reference clock
peer system peer association ID
tc time constant and poll exponent (log2 s) (3-17)
mintc minimum time constant (log2 s) (3-10)
clock date and time of day
refid reference ID or kiss code
reftime reference time
offset combined offset of server relative to this host
sys_jitter combined system jitter
frequency frequency offset (PPM) relative to hardware clock
clk_wander clock frequency wander (PPM)
clk_jitter clock jitter
tai TAI-UTC offset (s)
leapsec NTP seconds when the next leap second is/was inserted
expire NTP seconds when the NIST leapseconds file expires

The jitter and wander statistics are exponentially-weighted RMS averages. The system jitter is defined in the NTPv4 specification; the clock jitter statistic is computed by the clock discipline module.

When the NTPv4 daemon is compiled with the OpenSSL software library, additional system variables are displayed, including some or all of the following, depending on the particular Autokey dance:

Variable Description
host Autokey host name for this host
ident Autokey group name for this host
flags host flags (see Autokey specification)
digest OpenSSL message digest algorithm
signature OpenSSL digest/signature scheme
update NTP seconds at last signature update
cert certificate subject, issuer and certificate flags
until NTP seconds when the certificate expires

Peer Variables

The following peer variables appear in the rv billboard for each association. Not all variables are displayed in some configurations.

Variable Description
associd association ID
status peer status word
source (remote) IP address and port
destination (local) IP address and port
leap leap indicator (0-3)
stratum stratum (0-15)
precision precision (log2 s)
rootdelay total roundtrip delay to the primary reference clock
rootdisp total root dispersion to the primary reference clock
refid reference ID or kiss code
reftime reference time
reach reach register (octal)
unreach unreach counter
hmode host mode (1-6)
pmode peer mode (1-5)
hpoll host poll exponent (log2 s) (3-17)
ppoll peer poll exponent (log2 s) (3-17)
headway headway (see Rate Management and the Kiss-o'-Death Packet)
flash flash status word
offset filter offset
delay filter delay
dispersion filter dispersion
jitter filter jitter
ident Autokey group name for this association
bias unicast/broadcast bias
xleave interleave delay (see NTP Interleaved Modes)

The bias variable is calculated when the first broadcast packet is received after the calibration volley. It represents the offset of the broadcast subgraph relative to the unicast subgraph. The xleave variable appears only the interleaved symmetric and interleaved modes. It represents the internal queuing, buffering and transmission delays for the preceding packet.

When the NTPv4 daemon is compiled with the OpenSSL software library, additional peer variables are displayed, including the following:

Variable Description
flags peer flags (see Autokey specification)
host Autokey server name
flags peer flags (see Autokey specification)
signature OpenSSL digest/signature scheme
initsequence initial key ID
initkey initial key index
timestamp Autokey signature timestamp

Clock Variables

The following clock variables appear in the cv billboard for each association with a reference clock. Not all variables are displayed in some configurations.

Variable Description
associd association ID
status clock status word
device device description
timecode ASCII time code string (specific to device)
poll poll messages sent
noreply no reply
badformat bad format
baddata bad date or time
fudgetime1 fudge time 1
fudgetime2 fudge time 2
stratum driver stratum
refid driver reference ID
flags driver flags