The interactive commands consist of a keyword (command_keyword) followed by zero to four arguments. You need to entry only enough characters of the command_keyword to uniquely identify it. The output of an interactive command is sent to the standard output by default. You can send the output of an interactive command 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 xntpdc program itself and do not result in NTP mode.

The following interactive commands are supported:

? [ command_keyword ]

Without an argument, print a list of ntpq command keywords. If command_keyword is specified, print function and usage information about the command_keyword.

delay milliseconds

Specify a time interval to add to timestamps included in requests which require authentication.

This enables (unreliable) server reconfiguration over long delay network paths or between machines whose clocks are unsynchronized. Because the server no longer requires timestamps in authenticated requests, this command may be obsolete.

help [ command_keyword ]

Without an argument, print a list of ntpq command keywords. If command_keyword is specified, print function and usage information about the command_keyword.

host hostname

Set the host (hostname) to which future queries are sent. Specify hostname as a host name or a numeric address.

hostnames [ yes | no ]

Print hostnames or numeric addresses in information displays.

Specify yes to print host names. Specify no to print numeric addresses.

The default is yes, unless the -n command line option is specified.

keyid keyid

Enable specification of a key number (keyid) to authenticate configuration requests. keyid must correspond to a key number the server has been configured to use for this purpose.

passwd

Prompt user to enter a password to authenticate configuration requests.

The password is not displayed , and must correspond to the key configured for use by the NTP server for this purpose. If the password does not correspond to the key configured for use by the NTP server, requests are not successful.

quit

Exit xntpdc.

timeout millseconds

Specify a timeout period for responses to server queries.

The default is approximately 8000 milliseconds. As xntpdc retries each query once after a timeout, the total waiting time for a timeout is twice the timeout value set.

Query commands result in NTP mode 7 packets containing requests for information being sent to the server. These control message commands are read-only commands in that they make no modification of the server configuration state.

The following control message commands are supported:

clkbug

Obtain debugging information for a reference clock driver. This information is provided only by some clock drivers.

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.

dmpeers

Obtain a list of peers for which the sserver is maintaining state, along with a summary of that state.

The peer summary list is identical to the output of the peers command, except for the character in the leftmost column. Characters only appear beside peers which 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 with which the server is currently synchronizing.

iostats

Print statistics counters maintained in the input-output module.

kerninfo

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.

listpeers

Obtain and print a brief list of the peers for which the server is maintaining 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 synchonization candidates. candidates.

loopinfo [ oneline | multiline ]

Print the values of selected loop filter variables.

The loop filter is the part of NTP which deals with adjusting the local system clock.

The oneline and multiline options specify the format in which this information is printed. multiline is the default.

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.

memstats

Print statistics counters related to memory allocation code.

monlist [version]

Obtain and print traffic counts collected and maintained by the monitor facility. The version number should not normally need to be specified.

peers

Obtain a list of peers for which the server is maintaining state, along with a summary of that state.

The following summary information is included:

• Address of the remote peer.
• Local interface address. If a local address has yet to be determined it is 0.0.0.0.
• Stratum of the remote peer. A stratum of 16 indicates the remote peer is unsynchronized.
• Polling interval, in seconds.
• Reachability register, in octal.
• Current estimated delay, offset and dispersion of the peer, in seconds.
• Mode in which the peer entry is operating.

  This is represented by the character in the left margin. A + denotes symmetric active, a - indicates symmetric passive, a = means the remote server is being polled in client mode, a ^ indicates that the server is broadcasting to this address, a ~ denotes that the remote peer is sending broadcasts and a * marks the peer the server is currently synchonizing to.

• Host.

  This field may contain 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 is displayed.

pstats peer_address [...]

Show the per-peer statistic counters associated with the specified peers.

reslist

Obtain and print the server's restriction list.

Generally, this list is printed in sorted order.

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.

sysinfo

Print a variety of system state variables that are related to the local server.

The output from sysinfo is described in NTP Version 3 specification, RFC-1305. 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 xntpd 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 most architectures, this value initially decreases 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.

sysstats

Print statistics counters maintained in the protocol module.

timerstats

Print statistics counters maintained in the timer/event queue support code.

The server authenticates all requests that cause state changes in the server. The server uses a configured NTP key to accomplish this. This facility can also be disabled by the server by not configuring a key).

You must make the key number and the corresponding key known to xtnpdc. Use the keyid or passwd commands to do so.

The passwd command prompts users for a password to use as the encryption key. It also prompts automatically for both the key number and password the first time a command which would result in an authenticated request to the server is given. Authentication provides verification that the requester has permission to make such changes. It also gives an extra degree of protection against transmission errors.

Authenticated requests always include a time stamp in the packet data. The time stamp is included in the computation of the authentication code. This timestamp is compared by the server to its receive time stamp. If the time stamps differ by more than a small amount the request is rejected.

Time stamps are rejected for two reasons. First, it makes simple replay attacks on the server, by someone who might be able to overhear traffic on your LAN, much more difficult. Second, it makes it more difficult to request configuration changes to your server from topologically remote hosts.

While the reconfiguration facility works well with a server on the local host, and may work adequately between time-synchronized hosts on the same LAN, it works very poorly for more distant hosts. If reasonable passwords are chosen, care is taken in the distribution and protection of keys and appropriate source address restrictions are applied, the run time reconfiguration facility should provide an adequate level of security.

The following commands make authenticated requests.

addpeer peer_address [ keyid ] [ version ] [ prefer ]

Add a configured peer association at the given address and operating in symmetric active mode. 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 non-zero integer, all outgoing packets to the remote server will have an authentication field attached encrypted with this key. If the keyid is 0 or omitted, no authentication is done.

Specify version as 1, 2 or 3. The default is 3.

The prefer keyword indicates a preferred peer. This keyword is used primarily for clock synchronisation if possible. The preferred peer also determines the validity of the PPS signal - if the preferred peer is suitable for synchronisation so is the PPS signal.

addserver peer_address [ keyid ] [ version ] [ prefer ]

Identical to the addpeer command, except that the operating mode is client.

addtrap [ address [ port ] [ interface ]

Set a trap for asynchronous messages.

authinfo

Return information concerning the authentication module, including known keys and counts of encryptions and decryptions which have been done.

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.

clrtrap [ address [ port ] [ interface]

Clear a trap for asynchronous messages.

delrestrict address mask [ ntpport ]

Delete the matching entry from the restrict list.

fudge peer_address [ time1 ] [ time2 ] [ stratum ] [ refid ]

Provide a way to set certain data for a reference clock.

readkeys

Cause the current set of authentication keys to be purged and a new set to be obtained by re-reading the keys file. The keys file must have been specified in the xntpd configuration file. This enables encryption keys to be changed without restarting the server.

restrict address mask flag [ flag ]

This command operates in the same way as the restrict configuration file commands of xntpd.

reset

Clear the statistics counters in various modules of the server.

traps

Display the traps set in the server.

trustkey keyid [...]

untrustkey keyid [...]

These commands operate in the same way as the trustedkey and untrustkey configuration file commands of xntpd.

unconfig peer_address [...]

Cause the configured bit to be removed from the specified peers. 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 on in this fashion.

unrestrict address mask flag [ flag ]

Unrestrict the matching entry from the restrict list.