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NTPDC(8)		  BSD System Manager's Manual		      NTPDC(8)

NAME
     ntpdc — special NTP query program

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

DESCRIPTION
     The ntpdc utility is used to query the ntpd(8) daemon about its current
     state and to request changes in that state.  The program may be run
     either in interactive mode or controlled using command line arguments.
     Extensive state and statistics information is available through the ntpdc
     interface.	 In addition, nearly all the configuration options which can
     be specified at startup using ntpd's configuration file may also be spec‐
     ified at run time using ntpdc.

     The following options are available:

     -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 command
	     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.

     -i	     Force ntpdc to operate in interactive mode.  Prompts will be
	     written to the standard output and commands read from the stan‐
	     dard input.

     -l	     Obtain a list of peers which are known to the server(s).  This
	     switch is equivalent to ‘-c listpeers’.

     -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 sum‐
	     mary of their state.  This is equivalent to ‘c() peers’.

     -s	     Print a list of the peers known to the server as well as a sum‐
	     mary of their state, but in a slightly different format than the
	     -p switch.	 This is equivalent to ‘-c dmpeers’.

     If one or more request options are included on the command line when
     ntpdc 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, ntpdc 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.  The ntpdc util‐
     ity will prompt 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 net‐
     work which permits it.  Note that since NTP is a UDP protocol this commu‐
     nication will be somewhat unreliable, especially over large distances in
     terms of network topology.	 The ntpdc utility makes no attempt to
     retransmit requests, and will time requests out if the remote host is not
     heard from within a suitable timeout time.

     The operation of ntpdc are specific to the particular implementation of
     the ntpd(8) daemon and can be expected to work only with this and maybe
     some previous versions of the daemon.  Requests from a remote ntpdc util‐
     ity which affect the state of the local server must be authenticated,
     which requires both the remote program and local server share a common
     key and key identifier.

     Note that in contexts where a host name is expected, a -4 qualifier pre‐
     ceding the host name forces DNS resolution to the IPv4 namespace, while a
     -6 qualifier forces DNS resolution to the IPv6 namespace.	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,
     ntpdc will attempt to read interactive format commands from the standard
     input.

   Interactive Commands
     Interactive format commands consist of a keyword followed by zero to four
     arguments.	 Only enough characters of the full keyword to uniquely iden‐
     tify 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
     ntpdc utility itself and do not result in NTP mode 7 requests being sent
     to a server.  These are described following.

     ? command_keyword

     help command_keyword
	     A ‘?’ will print a list of all the command keywords known to this
	     incarnation of ntpdc.  A ‘?’ followed by a command keyword will
	     print function and usage information about the command.  This
	     command is probably a better source of information about ntpq(8)
	     than this manual page.

     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 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 dis‐
	     plays.  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 allows the specification of a key number to be used
	     to authenticate configuration requests.  This must correspond to
	     a key number the server has been configured to use for this pur‐
	     pose.

     quit    Exit ntpdc.

     passwd  This command prompts you to type in a password (which will not be
	     echoed) which will be used to authenticate configuration
	     requests.	The password must correspond to the key configured for
	     use by the NTP server for this purpose if such requests are to be
	     successful.

     timeout milliseconds
	     Specify a timeout period for responses to server queries.	The
	     default is about 8000 milliseconds.  Note that since ntpdc
	     retries each query once after a timeout, the total waiting time
	     for a timeout will be twice the timeout value set.

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

     listpeers
	     Obtains and prints 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 synchro‐
	     nization candidates.

     peers   Obtains a list of peers for which the server is maintaining
	     state, along with a summary of that state.	 Summary information
	     includes the address of the remote peer, the local interface
	     address (0.0.0.0 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 reachability 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.  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 cur‐
	     rently synchronizing to.

	     The contents of the host field may be one of four forms.  It may
	     be 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 will be displayed.

     dmpeers
	     A slightly different peer summary list.  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 ‘.’ indi‐
	     cates 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 [...]
	     Shows a detailed display of the current peer variables for one or
	     more peers.  Most of these values are described in the NTP Ver‐
	     sion 2 specification.

     pstats peer_address [...]
	     Show per-peer statistic counters associated with the specified
	     peer(s).

     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.

     kerninfo
	     Obtain and print kernel phase-lock loop operating parameters.
	     This information is available only if the kernel has been spe‐
	     cially 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 which 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 fil‐
	     ter.  The oneline and multiline options specify the format in
	     which this information is to be printed, with multiline as the
	     default.

     sysinfo
	     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 com‐
	     mands, respectively.  These are the auth, bclient, monitor, pll,
	     pps and stats flags.  See the ntpd(8) documentation for the mean‐
	     ing 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 modifi‐
	     cations 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
	     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
	     kern.clockrate.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.

     memstats
	     Print statistics counters related to memory allocation code.

     iostats
	     Print statistics counters maintained in the input-output module.

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

     reslist
	     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.	The version number should not normally need to
	     be specified.

     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
     All requests which cause state changes in the server are authenticated by
     the server using a configured NTP key (the facility can also be disabled
     by the server by not configuring a key).  The key number and the corre‐
     sponding key must also be made known to ntpdc.  This can be done using
     the keyid and passwd commands, the latter of which will prompt at the
     terminal for a password to use as the encryption key.  You will also be
     prompted 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 not only provides verification that the
     requester has permission to make such changes, but also gives an extra
     degree of protection again transmission errors.

     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 time stamp.  If they
     differ by more than a small amount the request is rejected.  This is done
     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 dif‐
     ficult.  Second, it makes it more difficult to request configuration
     changes to your server from topologically remote hosts.  While the recon‐
     figuration facility will work well with a server on the local host, and
     may work adequately between time-synchronized hosts on the same LAN, it
     will work very poorly for more distant hosts.  As such, 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 secu‐
     rity.

     The following commands all make authenticated requests.

     addpeer peer_address [keyid] [version] [prefer]
	     Add a configured peer association at the given address and oper‐
	     ating in symmetric active mode.  Note that an existing associa‐
	     tion with the same peer may be deleted when this command is exe‐
	     cuted, or may simply be converted to conform to the new configu‐
	     ration, as appropriate.  If the optional keyid is a nonzero inte‐
	     ger, 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 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 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.

     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 will cause the peer asso‐
	     ciation to be deleted.  When appropriate, however, the associa‐
	     tion may persist in an unconfigured mode if the remote peer is
	     willing to continue on in this fashion.

     fudge peer_address [time1] [time2] [stratum] [refid]
	     This command provides a way to set certain data for a reference
	     clock.  See the source listing for further information.

     enable [auth | bclient | calibrate | kernel | monitor | ntp | pps |
	     stats]

     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(8).

	     auth    Enables the server to synchronize with unconfigured peers
		     only if the peer has been correctly authenticated using
		     either public key or private key cryptography.  The
		     default for this flag is enable.

	     bclient
		     Enables the server to listen for a message from a broad‐
		     cast or multicast server, as in the multicastclient com‐
		     mand with default address.	 The default for this flag is
		     disable.

	     calibrate
		     Enables the calibrate feature for reference clocks.  The
		     default for this flag is disable.

	     kernel  Enables the kernel time discipline, if available.	The
		     default for this flag is enable if support is available,
		     otherwise disable.

	     monitor
		     Enables the monitoring facility.  See the ntpdc(8).  pro‐
		     gram and the monlist command or further information.  The
		     default for this flag is enable.

	     ntp     Enables time and frequency discipline.  In effect, this
		     switch opens and closes the feedback loop, which is use‐
		     ful for testing.  The default for this flag is enable.

	     pps     Enables the pulse-per-second (PPS) signal when frequency
		     and time is disciplined by the precision time kernel mod‐
		     ifications.  See the "A Kernel Model for Precision
		     Timekeeping" (available as part of the HTML documentation
		     provided in /usr/share/doc/ntp) page for further informa‐
		     tion.  The default for this flag is disable.

	     stats   Enables the statistics facility.  See the Monitoring
		     Options section of ntp.conf(5) for further information.
		     The default for this flag is disable.

     restrict address mask flag [...]
	     This command operates in the same way as the restrict configura‐
	     tion file commands of ntpd(8).

     unrestrict address mask flag [...]
	     Unrestrict the matching entry from the restrict list.

     delrestrict address mask [ntpport]
	     Delete the matching entry from the restrict list.

     readkeys
	     Causes the current set of authentication keys to be purged and a
	     new set to be obtained by rereading the keys file (which must
	     have been specified in the ntpd(8) configuration file).  This
	     allows encryption keys to be changed without restarting the
	     server.

     trustedkey keyid [...]

     untrustedkey keyid [...]
	     These commands operate in the same way as the trustedkey and
	     untrustedkey configuration file commands of ntpd(8).

     authinfo
	     Returns information concerning the authentication module, includ‐
	     ing known keys and counts of encryptions and decryptions which
	     have been done.

     traps   Display the traps set in the server.  See the source listing for
	     further information.

     addtrap address [port] [interface]
	     Set a trap for asynchronous messages.  See the source listing for
	     further information.

     clrtrap address [port] [interface]
	     Clear a trap for asynchronous messages.  See the source listing
	     for further information.

     reset   Clear the statistics counters in various modules of the server.
	     See the source listing for further information.

SEE ALSO
     ntp.conf(5), ntpd(8)

     David L. Mills, Network Time Protocol (Version 3), RFC1305.

BUGS
     The ntpdc utility is a crude hack.	 Much of the information it shows is
     deadly boring and could only be loved by its implementer.	The program
     was 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.

BSD				 May 17, 2006				   BSD
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