Query the NTP daemon


ntpdc [-46ilnps] [-c command] [host] [...]  

Runs on:



Force DNS resolution of hosts to the IP4 namespace.
Force DNS resolution of hosts to the IP6 namespace.
-c command
Execute the given command on the specified hosts. You can use multiple -c options. For more information about the commands, see below.
Force the ntpdc utility to operate in interactive mode. Prompts will be written to the standard output and commands read from the standard input.
Obtain a list of peers that are known to the servers. It is equivalent to -c listpeers option.
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 along with the summary of their state. This is equivalent to the -c peers option.
Print a list of the peers known to the server along with the summary of their state. It has slightly different format than the -p option. This is equivalent to -c dmpeers command.


Use the ntpdc utility to query the ntpd daemon about its current state, and to request changes in that state. You can run this utility is run either in interactive mode or in command mode. It provides extensive state and statistics information. At run time, all configuration options that are specified at startup using the ntpd utility's configuration file can also be specified using the ntpdc utility.

When you run the ntpdc utility by including one or more requests in the command line, each request is sent to the NTP (Network Time Protocol) servers running on each of the hosts. If no request option is given, the ntpdc utility attempts to read commands from the standard input and execute them on the NTP server running on the first host, as given on the command line. If no host is mentioned, it always defaults to localhost. The ntpdc utility prompts for commands if the standard input is a terminal device.

The ntpdc utility uses NTP mode 7 packets to communicate with the NTP server, and hence can be used to query any compatible server on the network that permits it. However it is somewhat unreliable, especially over large distances in a network topology. The ntpdc utility makes no attempt to retransmit requests, and times out if the remote host's response isn't received within a suitable timeout time.

Note: NTP behaves very similar to UDP (User Datagram Protocol).

You may force the DNS resolution to the IPv4 (or IPv6) namespace, if you use a -4 (or -6) option before a host name.

Interactive commands

The interactive format commands consist of a keyword followed by zero or more arguments. You can type only enough characters to uniquely identify the command. The output of a command is normally sent to the standard output, but you can send 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 ntpdc utility:

? [command_keyword] or help [command_keyword]
Print a list of all the command keywords for the ntpdc utility. If you specify a command keyword, the function and the usage information about the command are printed.
delay milliseconds
Specify a time interval. This is to be added to timestamps for requests that require authentication.
host hostname
Set the host to which future queries will be sent. The hostname may be either a host name or a numeric address.
hostnames [yes | no]
Print the host names in the information display when yes is specified. Print the numeric address when no is specified. The default is yes, unless modified using the command-line -n option.
keyid keyid
Set the key number to use to authenticate configuration requests. This must correspond to a key number that the server has been configured to.
Prompt for a password, which is not echoed, and is used to authenticate configuration requests. The password must correspond to the key configured for the NTP server for this purpose.
Exit the ntpdc utility.
timeout milliseconds
Specify a timeout period for responses to server queries. The default is about 8000 milliseconds. Since the ntpdc utility retries each query once after a timeout, the total waiting time for a timeout will be twice the timeout value set.

Control message commands

When you use the ntpdc utility to query, NTP mode 7 packets containing requests are sent to the server. These are read-only commands in that they make no modification of the server configuration state.

Obtain and print a brief list of the peers for which the server is maintaining the state. These should include all configured peer associations as well as those peers whose stratum is such that they are considered by the server to be possible future synchronization candidates.
Obtain a list of peers for which the server is maintaining the state, along with a summary of that state. Summary information includes the address of the remote peer, the local interface address ( if a local address has yet to be determined), the stratum of the remote peer (a stratum of 16 indicates the remote peer is unsynchronized), the polling interval, in seconds, the register in octal, and the current estimated delay, offset and dispersion of the peer, all in seconds.

The character in the left margin indicates the mode this peer entry is operating in.

This Character: Indicates:
+ Symmetric active
- Symmetric passive
= Remote server is being polled in client mode
^ Server is broadcasting to this address
* Server is currently synchronizing to this peer.

The contents of the host field may be one of:

  • a host name
  • an IP address
  • a reference clock implementation name with its parameter or REFCLK(implementation number, parameter).

If you've specified no, only IP-addresses are displayed.

Obtain peer summary list, identical to the output of the peers command, except for the character in the leftmost column. Characters appear only beside peers that were included in the final stage of the clock selection algorithm. A . indicates that this peer was cast off in the falseticker detection, while a + indicates that the peer made it through. A * denotes the peer the server is currently synchronizing with.
showpeer peer_address [...]
Show a detailed display of the current peer variables for one or more peers. Most of these values are described in the NTP version 2 specification.
pstats peer_address [...]
Show per-peer statistic counters associated with the specified peers.
clockinfo clock_peer_address [...]
Obtain and print information concerning a peer clock. The values obtained provide information on the setting of fudge factors and other clock performance information.
Obtain and print kernel phase-lock loop operating parameters. This information is available only if the kernel has been specially modified for a precision timekeeping function.
loopinfo [oneline | multiline]
Print the values of selected loop filter variables. The loop filter is the part of NTP that deals with adjusting the local system clock. The offset is the last offset given to the loop filter by the packet-processing code. The frequency is the frequency error of the local clock in parts-per-million (ppm). The time_const controls the stiffness of the phase-lock loop and thus the speed at which it can adapt to oscillator drift. The watchdog timer value is the number of seconds which have elapsed since the last sample offset was given to the loop filter. The oneline and multiline options specify the format in which this information is to be printed, with multiline as the default.
Print a variety of system state variables, i.e., state related to the local server. All except the last four lines are described in the NTP Version 3 specification, RFC 1305.

The system flags show various system flags, some of which can be set and cleared by the enable and disable configuration commands, respectively. These are the auth, bclient, monitor, pll, pps and stats flags. See the ntpd documentation for the meaning of these flags.

There are two additional flags which are read only, the kernel_pll and kernel_pps. These flags indicate the synchronization status when the precision time kernel modifications are in use. The kernel_pll indicates that the local clock is being disciplined by the kernel, while the kernel_pps indicates the kernel discipline is provided by the PPS signal.

The stability is the residual frequency error remaining after the system frequency correction is applied and is intended for maintenance and debugging. In QNX Neutrino, this value will initially decrease from as high as 500 ppm to a nominal value in the range .01 to 0.1 ppm. If it remains high for some time after starting the daemon, something may be wrong with the local clock, or the value of the kernel variable tick may be incorrect. The broadcastdelay shows the default broadcast delay, as set by the broadcastdelay configuration command. The authdelay shows the default authentication delay, as set by the authdelay configuration command.

Print statistic counters maintained in the protocol module.
Print statistic counters related to memory-allocation code.
Print statistic counters maintained in the input-output module.
Print statistic counters maintained in the timer/event queue support code.
Obtain and print the server's restriction list. This list is (usually) printed in sorted order and may help to understand how the restrictions are applied.
monlist [version]
Obtain and print traffic counts collected and maintained by the monitor facility. You don't normally have to specify the version number.
clkbug clock_peer_address [...]
Obtain debugging information for a reference clock driver. This information is provided only by some clock drivers and is mostly undecodable without a copy of the driver source in hand.

Runtime configuration requests

With the help of a configured NTP key, the server authenticates all requests. Authenticated requests always include a timestamp in the packet data, which is included in the computation of the authentication code. This timestamp is compared by the server to its receive timestamp. If they differ by more than a small amount, the request is rejected. The following commands all make authenticated requests:

addpeer peer_address [keyid] [version] [prefer]
Add a configured peer association at the given address and operating in symmetric active mode. Note that an existing association with the same peer may be deleted when this command is executed, or may simply be converted to conform to the new configuration, as appropriate.

If the optional keyid is a nonzero integer, all outgoing packets to the remote server will have an authentication field attached encrypted with this key. If the value is 0 (or not given) no authentication will be done. The version number can be 1, 2 or 3, and defaults to 3. The prefer keyword indicates a preferred peer (and thus will be used primarily for clock synchronization if possible). The preferred peer also determines the validity of the PPS signal; if the preferred peer is suitable for synchronization, so is the PPS signal.

addserver peer_address [keyid] [version] [prefer]
Identical to the addpeer command, except that the operating mode is client.
broadcast peer_address [keyid] [version] [prefer]
Identical to the addpeer command, except that the operating mode is broadcast. In this case, a valid key identifier and key are required. The peer_address parameter can be the broadcast address of the local network or a multicast group address assigned to NTP. If a multicast address, a multicast-capable kernel is required.
unconfig peer_address [...]
This command causes the configured bit to be removed from the specified peer(s). In many cases, this causes the peer association to be deleted. When appropriate, however, the association may persist in an unconfigured mode if the remote peer is willing to continue in this fashion.
fudge peer_address [time1] [time2] [stratum] [refid]
This command provides a way to set certain data for a reference clock.
enable [auth | bclient | calibrate | kernel | monitor | ntp | pps | stats] or disable [auth | bclient | calibrate | kernel | monitor | ntp | pps | stats]
These commands operate in the same way as the enable and disable configuration file commands of ntpd.
restrict address mask flag [flag]
This command operates in the same way as the restrict configuration file commands of the ntpd utility.
unrestrict address mask flag [flag]
Unrestrict the matching entry from the restriction list.
delrestrict address mask [ntpport]
Delete the matching entry from the restriction list.
Purge the current set of authentication keys and obtain a new set by rereading the keys file (which must have been specified in the ntpd configuration file). This allows encryption keys to be changed without restarting the server.
trustedkey keyid [...] or untrustedkey keyid [...]
These commands operate in the same way as the trustedkey and untrustedkey configuration file commands of ntpd.
Return information concerning the authentication module, including known keys and counts of encryptions and decryptions that have been done.
Display the traps set in the server.
addtrap [address [port] [interface]
Set a trap for asynchronous messages.
clrtrap [address [port] [interface]
Clear a trap for asynchronous messages.
Clear the statistics counters in various modules of the server.


The ntpdc utility is a crude hack. It is designed so that new (and temporary) features were easy to hack in, at great expense to the program's ease of use. Despite this, the program is occasionally useful.