ntpq
ntpq(8) ntpq(8)
NAME
ntpq - standard NTP query program
SYNOPSIS
ntpq [-46dinp] [-c command] [host] [...]
DESCRIPTION
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
RFC1305. The same formats are used in NTPv4, although some of the
variables 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 stan-
dard input.
-4 Force DNS resolution of following host names on the command
line to the IPv4 namespace.
-6 Force DNS resolution of following host names on the command
line to the IPv6 namespace.
-c 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.
-d Turn on debugging mode.
-i Force ntpq to operate in interactive mode. Prompts will be
written to the standard output and commands read from the
standard input.
-n Output all host addresses in dotted-quad numeric format rather
than converting to the 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 inter-
active 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 nor-
mally sent to the standard output, but optionally the output of indi-
vidual commands may be sent to a file by appending a >, followed by a
file name, to the command line. A number of interactive format com-
mands 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]
helpl [command_keyword]
A ? by itself will print a list of all the command keywords
known to this incarnation of ntpq. A ? followed by a command
keyword will print function and usage information about the
command. This command is probably a better source of informa-
tion about ntpq than this manual page.
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 variable_name = value, 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 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 individ-
ual variables from the list, while the clearlist command
removes all variables from the list.
cooked Causes output from query commands to be "cooked", so that
variables which are recognized by ntpq will have their values
reformatted for human consumption. Variables which ntpq thinks
should have a decodable value but didn’t are marked with a
trailing ?.
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 authen-
ticated requests, so this command may be obsolete.
host hostname
Set the host to which future queries will be sent. Hostname
may be either a host 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 authenti-
cate configuration requests. This must correspond to a key
number the server has been configured to use for this purpose.
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.
passwd This command prompts for a password (which will not be echoed)
which will be used to authenticate configuration requests. The
password must correspond to the key configured for NTP server
for this purpose.
quit Exit ntpq.
raw Causes all output from query commands is printed as received
from the remote server. The only formatting/interpretation
done on the data is to transform non-ASCII data into a print-
able (but barely understandable) form.
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
Each association known to an NTP server has a 16 bit integer associa-
tion identifier. NTP control messages which carry peer variables must
identify the peer the values correspond to by including its associa-
tion ID. An association ID of 0 is special, and indicates the vari-
ables 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
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
numbering the associations from 1 for internal use, the second
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. See the peers command for a decode of the condition
field. Note that the data returned by the 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 argu-
ment, the form &index may be used as an alternative.
clockvar [assocID] [variable_name [ = value [...]] [...]
cv [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 synchro-
nization will respond positively to this. If the association
identifier is omitted or zero the request is for the variables
of the 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 associa-
tion ID will show the variables of a particular clock. Omit-
ting the variable list will cause the server to return a
default variable display.
lassociations
Obtains and prints a list of association identifiers and peer
statuses for all associations for which the server is main-
taining state. This command differs from the associations com-
mand 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 com-
mand is used, but are included in the output of lassociations.
lpassociations
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
fuzzballs.
lpeers Like R 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 fuzzball servers.
mreadlist assocID assocID
mrl assocID assocID
Like the readlist command, except the query is done for each
of a range of (nonzero) association IDs. This range is deter-
mined from the association list cached by the most recent
associations command.
mreadvar assocID assocID [ variable_name [ = value[ ... ]
mrv 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 associa-
tions command.
opeers An old form of the peers command with the reference ID
replaced by the local interface address.
passociations
Displays association data concerning in-spec peers from the
internally cached list of associations. This command performs
identically to the associations except that it displays the
internally stored data rather than making a new query.
peers Obtains a current list peers of the server, along with a sum-
mary of each peer’s state. Summary information includes the
address of the remote peer, the reference ID (0.0.0.0 if this
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, and the current estimated
delay, offset and dispersion of the peer, all in milliseconds.
The character at the left margin of each line shows the syn-
chronization status of the association and is a valuable diag-
nostic tool. The encoding and meaning of this character,
called the tally code, is given later in this page.
pstatus assocID
Sends a read status request to the server for the given asso-
ciation. 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
pidgeon English.
readlist [ assocID ]
rl [ 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.
readvar assocID variable_name [ = value ] [ ...]
rv assocID [ 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 vari-
ables 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 dis-
play. The encoding and meaning of the variables derived from
NTPv3 is given in RFC-1305; the encoding and meaning of the
additional NTPv4 variables are given later in this page.
writevar assocID variable_name [ = value [ ...]
Like the readvar request, except the specified variables are
written instead of read.
writelist [ assocID ]
Like the readlist request, except the internal list variables
are written instead of read.
TALLY CODES
The character in the left margin in the peers billboard, called the
tally code, shows the fate of each association in the clock selection
process. Following is a list of these characters, the pigeon used in
the rv command, and a short explanation of the condition revealed.
space reject
The peer is discarded as unreachable, synchronized to this
server (synch loop) or outrageous synchronization distance.
x falsetick
The peer is discarded by the intersection algorithm as a
falseticker.
. excess
The peer is discarded as not among the first ten peers sorted
by synchronization distance and so is probably a poor candi-
date for further consideration.
- outlyer
The peer is discarded by the clustering algorithm as an out-
lyer.
+ candidat
The peer is a survivor and a candidate for the combining algo-
rithm.
# selected
The peer is a survivor, but not among the first six peers
sorted by synchronization distance. If the association is
ephemeral, it may be demobilized to conserve resources.
* sys.peer
The peer has been declared the system peer and lends its vari-
ables to the system variables.
o pps.peer
The peer has been declared the system peer and lends its vari-
ables to the system variables. However, the actual system syn-
chronization is derived from a pulse-per-second (PPS) signal,
either indirectly via the PPS reference clock driver or
directly via kernel interface.
SYSTEM VARIABLES
The status, leap, stratum, precision, rootdelay, rootdispersion,
refid, reftime, poll, offset, and frequency variables are described in
RFC-1305 specification. Additional NTPv4 system variables include the
following.
version Everything you might need to know about the software version
and generation time.
processor
The processor and kernel identification string.
system The operating system version and release identifier.
state The state of the clock discipline state machine. The values
are described in the architecture briefing on the NTP Project
page linked from www.ntp.org.
peer The internal integer used to identify the association cur-
rently designated the system peer.
jitter The estimated time error of the system clock measured as an
exponential average of RMS time differences.
stability
The estimated frequency stability of the system clock measured
as an exponential average of RMS frequency differences.
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 dance:
flags The current flags word bits and message digest algorithm iden-
tifier (NID) in hex format. The high order 16 bits of the
four-byte word contain the NID from the OpenSSL ligrary, while
the low-order bits are interpreted as follows:
0x01 autokey enabled
0x02 NIST leapseconds file loaded
0x10 PC identity scheme
0x20 IFF identity scheme
0x40 GQ identity scheme
hostname
The name of the host as returned by the Unix gethostname()
library function.
hostkey The NTP filestamp of the host key file.
cert A list of certificates held by the host. Each entry includes
the subject, issuer, flags and NTP filestamp in order. The
bits are interpreted as follows:
0x01 certificate has been signed by the server
0x02 certificate is trusted
0x04 certificate is private
0x08 certificate contains errors and should not be trusted
leapseconds
The NTP filestamp of the NIST leapseconds file.
refresh The NTP timestamp when the host public cryptographic values
were refreshed and signed.
signature
The host digest/signature scheme name from the OpenSSL
library.
tai The TAI-UTC offset in seconds obtained from the NIST leapsec-
onds table.
PEER VARIABLES
The status, srcadr, srcport, dstadr, dstport, leap, stratum, preci-
sion, rootdelay, rootdispersion, readh, hmode, pmode, hpoll, ppoll,
offset, delay, dspersion, reftime variables are described in the
RFC-1305 specification, as are the timestamps org, rec and xmt. Addi-
tional NTPv4 system variables include the following.
flash The flash code for the most recent packet received. The encod-
ing and meaning of these codes is given later in this page.
jitter The estimated time error of the peer clock measured as an
exponential average of RMS time differences.
unreach The value of the counter which records the number of poll
intervals since the last valid packet was received.
When the NTPv4 daemon is compiled with the OpenSSL software library,
additional peer variables are displayed, including the following:
flags The current flag bits. This word is the server host status
word with additional bits used by the Autokey state machine.
See the source code for the bit encoding.
hostname
The server host name.
initkey key
The initial key used by the key list generator in the Autokey
protocol.
initsequence index
The initial index used by the key list generator in the
Autokey protocol.
signature
The server message digest/signature scheme name from the
OpenSSL software library.
timestamp time
The NTP timestamp when the last Autokey key list was generated
and signed.
FLASH CODES
The flash code is a valuable debugging aid displayed in the peer vari-
ables list. It shows the results of the original sanity checks defined
in the NTP specification RFC-1305 and additional ones added in NTPv4.
There are 12 tests designated TEST1 through TEST12. The tests are per-
formed in a certain order designed to gain maximum diagnostic informa-
tion while protecting against accidental or malicious errors. The
flash variable is initialized to zero as each packet is received. If
after each set of tests one or more bits are set, the packet is dis-
carded.
Tests TEST1 through TEST3 check the packet timestamps from which the
offset and delay are calculated. If any bits are set, the packet is
discarded; otherwise, the packet header variables are saved. TEST4 and
TEST5 are associated with access control and cryptographic authentica-
tion. If any bits are set, the packet is discarded immediately with
nothing changed.
Tests TEST6 through TEST8 check the health of the server. If any bits
are set, the packet is discarded; otherwise, the offset and delay rel-
ative to the server are calculated and saved. TEST9 checks the health
of the association itself. If any bits are set, the packet is dis-
carded; otherwise, the saved variables are passed to the clock filter
and mitigation algorithms.
Tests TEST10 through TEST12 check the authentication state using
Autokey public-key cryptography, as described in the Authentication
Options page. If any bits are set and the association has previously
been marked reachable, the packet is discarded; otherwise, the origi-
nate and receive timestamps are saved, as required by the NTP proto-
col, and processing continues.
The flash bits for each test are defined as follows.
0x001 TEST1
Duplicate packet. The packet is at best a casual retransmis-
sion and at worst a malicious replay.
0x002 TEST2
Bogus packet. The packet is not a reply to a message previ-
ously sent. This can happen when the NTP daemon is restarted
and before somebody else notices.
0x004 TEST3
Unsynchronized. One or more timestamp fields are invalid. This
normally happens when the first packet from a peer is
received.
0x008 TEST4
Access is denied. See the Access Control Options page.
0x010 TEST5
Cryptographic authentication fails. See the Authentication
Options page.
0x020 TEST6
The server is unsynchronized. Wind up its clock first.
0x040 TEST7
The server stratum is at the maximum than 15. It is probably
unsynchronized and its clock needs to be wound up.
0x080 TEST8
Either the root delay or dispersion is greater than one sec-
ond, which is highly unlikely unless the peer is unsynchro-
nized to Mars.
0x100 TEST9
Either the peer delay or dispersion is greater than one sec-
ond, which is highly unlikely unless the peer is on Mars.
0x200 TEST10
The autokey protocol has detected an authentication failure.
See the Authentication Options page.
0x400 TEST11
The autokey protocol has not verified the server or peer is
proventic and has valid public key credentials. See the
Authentication Options page.
0x800 TEST12
A protocol or configuration error has occurred in the public
key algorithms or a possible intrusion event has been
detected. See the Authentication Options page.
BUGS
The peers command is non-atomic and may occasionally result in spuri-
ous error messages about invalid associations occurring and terminat-
ing 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.
SEE ALSO
ntpd(8), ntpdc(8)
Primary source of documentation: /usr/share/doc/ntp-*
This file was automatically generated from HTML source.
ntpq(8)
