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xntpdc - special NTP query program
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<code>xntpdc</code> - special NTP query program
</h3><hr>

<p><h4>Synopsis</h4>

<p><code>xntpdc [ -ilnps ] [ -c <i>command</i> ] [ <i>host</i> ] [ ...
]</code>

<p><h4>Description</h4>

<p><code>xntpdc</code> is used to query the <code>xntpd</code> 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 <code>xntpdc</code> interface. In addition, nearly
all the configuration options which can be specified at start up using
xntpd's configuration file may also be specified at run time using
<code>xntpdc</code>.

<p>If one or more request options is included on the command line when
<code>xntpdc</code> 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,
<code>xntpdc</code> 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. <code>xntpdc</code> will prompt for commands if the
standard input is a terminal device.

<p><code>xntpdc</code> uses NTP mode 7 packets to communicate with the
NTP server, and hence can be used to query any compatable 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. <code>xntpdc</code> makes no
attempt to retransmit requests, and will time requests out if the remote
host is not heard from within a suitable timeout time.

<p>The operation of <code>xntpdc</code> are specific to the particular
implementation of the <code>xntpd</code> daemon and can be expected to
work only with this and maybe some previous versions of the daemon.
Requests from a remote <code>xntpdc</code> program 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.

<p><h4>Command Line Options</h4>

<p>Specifying a command line option other than <code>-i</code> or
<code>-n</code> will cause the specified query (queries) to be sent to
the indicated host(s) immediately. Otherwise, <code>xntpdc</code> will
attempt to read interactive format commands from the standard input.

<dl>

<dt><code>-c <i>command</i></code>
<dd>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.

<p><dt><code>-i</code>
<dd>Force <code>xntpdc</code> to operate in interactive mode. Prompts
will be written to the standard output and commands read from the
standard input.
<p><dt><code>-l</code>
<dd>Obtain a list of peers which are known to the server(s). This switch
is equivalent to <code>-c listpeers</code>.

<p><dt><code>-n</code>
<dd>Output all host addresses in dotted-quad numeric format rather than
converting to the canonical host names.

<p><dt><code>-p</code>
<dd>Print a list of the peers known to the server as well as a summary
of their state. This is equivalent to <code>-c peers</code>.

<p><dt><code>-s</code>
<dd>Print a list of the peers known to the server as well as a summary
of their state, but in a slightly different format than the -p switch.
This is equivalent to <code>-c dmpeers</code>.

</dl>

<p><h4>Interactive Commands</h4>

<p>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 <code>&lt;</code>,
followed by a file name, to the command line.

<p>A number of interactive format commands are executed entirely within
the <code>xntpdc</code> program itself and do not result in NTP mode 7
requests being sent to a server. These are described following.

<dl>

<dt><code>? [ <i>command_keyword</i> ]</code>
<br><code>helpl [ <i>command_keyword</i> ]</code>
<dd>A <code>?</code> by itself will print a list of all the command
keywords known to this incarnation of <code>ntpq</code>. A
<code>?</code> followed by a command keyword will print funcation and
usage information about the command. This command is probably a better
source of information about <code>ntpq</code> than this manual page.

<p><dt><code>delay <i>milliseconds</i></code>
<dd>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.

<p><dt><code>host <i>hostname</i></code>
<dd>Set the host to which future queries will be sent. Hostname may be
either a host name or a numeric address.

<p><dt><code>hostnames [ yes | no ]</code>
<dd>If <code>yes</code> is specified, host names are printed in
information displays. If <code>no</code> is specified, numeric addresses
are printed instead. The default is <code>yes</code>, unless modified
using the command line <code>-n</code> switch.

<p><dt><code>keyid <i>keyid</i></code>
<dd>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 purpose.
<p><dt><code>quit</code>
<dd>Exit <code>xntpdc</code>.

<p><dt><code>passwd</code>
<dd>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.

<p><dt><code>timeout <i>millseconds</i></code>
<dd>Specify a timeout period for responses to server queries. The
default is about 8000 milliseconds. Note that since <code>xntpdc</code>
retries each query once after a timeout, the total waiting time for a
timeout will be twice the timeout value set.

</dl>

<p><h4>Control Message Commands</h4>

<p>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.

<dl>

<dt><code>listpeers</code>
<dd>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 synchonization candidates.

<p><dt><code>peers</code>
<dd>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. In addition, the character in the left margin indicates the
mode this peer entry is operating in. A <code>+</code> denotes symmetric
active, a <code>-</code> indicates symmetric passive, a <code>=</code>
means the remote server is being polled in client mode, a <code>^</code>
indicates that the server is broadcasting to this address, a
<code>~</code> denotes that the remote peer is sending broadcasts and a
<code>*</code> marks the peer the server is currently synchonizing to.

<p>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 <code>REFCLK(<i>implementation number</i>,
<i>parameter</i>)</code>. On <code>hostnames no</code> only IP-addresses
will be displayed.

<p><dt><code>dmpeers</code>
<dd>A slightly different peer summary list. Identical to the output of
the <code>peers</code> 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 <code>.</code> indicates
that this peer was cast off in the falseticker detection, while a
<code>+</code> indicates that the peer made it through. A <code>*</code>
denotes the peer the server is currently synchronizing with.

<p><dt><code>showpeer <i>peer_address</i> [...]</code>
<dd>Shows 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.
<p><dt><code>pstats <i>peer_address</i> [...]</code>
<dd>Show per-peer statistic counters associated with the specified
peer(s).

<p><dt><code>clockinfo <i>clock_peer_address</i> [...]</code>
<dd>Obtain and print information concerning a peer clock. The values
obtained provide information on the setting of fudge factors and other
clock performance information.

<p><dt><code>kerninfo</code>
<dd>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.

<p><dt><code>loopinfo [ oneline | multiline ]</code>
<dd>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 <code>offset</code> is the last offset given to the loop filter by
the packet processing code. The <code>frequency</code> is the frequency
error of the local clock in parts-per-million (ppm). The
<code>time_const</code> controls the stiffness of the phase-lock loop
and thus the speed at which it can adapt to oscillator drift. The
<code>watchdog timer</code> value is the number of seconds which have
elapsed since the last sample offset was given to the loop filter. The
<code>oneline</code> and <code>multiline</code> options specify the
format in which this information is to be printed, with
<code>multiline</code> as the default.

<p><dt><code>sysinfo</code>
<dd>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.

<dl>

<dd>The <code>system flags</code> show various system flags, some of
which can be set and cleared by the <code>enable</code> and
<code>disable</code> configuration commands, respectively. These are the
<code>auth</code>, <code>bclient</code>, <code>monitor</code>,
<code>pll</code>, <code>pps</code> and <code>stats</code> flags. See the
<code>xntpd</code> documentation for the meaning of these flags. There
are two additional flags which are read only, the
<code>kernel_pll</code> and <code>kernel_pps</code>. These flags
indicate the synchronization status when the precision time kernel
modifications are in use. The <code>kernel_pll</code> 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.

<p><dd>The <code>stability</code> 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 <code>tick</code> may be incorrect.

<p><dd>The <code>broadcastdelay</code> shows the default broadcast
delay, as set by the <code>broadcastdelay</code> configuration command.

<p><dd>The <code>authdelay</code> shows the default authentication
delay, as set by the <code>authdelay</code> configuration command.

</dl>

<p><dt><code>sysstats</code>
<dd>Print statistics counters maintained in the protocol module.
<p><dt><code>memstats</code>
<dd>Print statistics counters related to memory allocation code.

<p><dt><code>iostats</code>
<dd>Print statistics counters maintained in the input-output module.

<p><dt><code>timerstats</code>
<dd>Print statistics counters maintained in the timer/event queue
support code.

<p><dt><code>reslist</code>
<dd>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.

<p><dt><code>monlist [ <i>version</i> ]</code>
<dd>Obtain and print traffic counts collected and maintained by the
monitor facility. The version number should not normally need to be
specified.

<p><dt><code>clkbug <i>clock_peer_address</i> [...]</code>
<dd>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.

</dl>

<p><h4>Runtime Configuration Requests</h4>

<p>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 corresponding key must also be made known to xtnpdc. 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.

<p>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
difficult. Second, it makes it more difficult to request configuration
changes to your server from topologically remote hosts. While the
reconfiguration 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
security.

<p>The following commands all make authenticated requests.

<dl>

<dt><code>addpeer <i>peer_address</i> [ <i>keyid</i> ] [
<i>version</i> ] [ <i>prefer</i> ]</code>
<dd>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 <code>keyid</code> 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 <code>version#</code> can be 1, 2 or 3
and defaults to 3. The <code>prefer</code> 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.

<p><dt><code>addserver <i>peer_address</i> [ <i>keyid</i> ] [
<i>version</i> ] [ <i>prefer</i> ]</code>
<dd>Identical to the addpeer command, except that the operating mode is
client.

<p><dt><code>broadcast <i>peer_address</i> [ <i>keyid</i> ] [
<i>version</i> ] [ <i>prefer</i> ]</code>
<dd>Identical to the addpeer command, except that the operating mode is
broadcast. In this case a valid key identifier and key are required. The
<code>peer_address</code> 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.

<p><dt><code>unconfig <i>peer_address</i> [...]</code>
<dd>This command causes the configured bit to be removed from the
specified peer(s). In many cases this will cause 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.

<p><dt><code>fudge <i>peer_address</i> [ <i>time1</i> ] [ <i>time2</i> ]
[ <i>stratum</i> ] [ <i>refid</i> ]</code>
<dd>This command provides a way to set certain data for a reference
clock. See the source listing for further information.

<p><dt><code>enable [ <i>flag</i> ] [ ... ]</code>
<br><code>disable [ <i>flag</i> ] [ ... ]</code>
<dd>These commands operate in the same way as the <code>enable</code>
and <code>disable</code> configuration file commands of
<code>xntpd</code>. Following is a description of the flags. Note that
only the <code>auth</code>, <code>bclient</code>, <code>monitor</code>,
<code>pll</code>, <code>pps</code> and <code>stats</code> flags can be
set by <code>xntpdc</code>; the <code>pll_kernel</code> and
<code>pps_kernel</code> flags are read-only.

<dl>

<dt><code>auth</code>
<dd>Enables the server to synchronize with unconfigured peers only if
the peer has been correctly authenticated using a trusted key and key
identifier. The default for this flag is enable.

<p><dt><code>bclient</code>
<dd>Enables the server to listen for a message from a broadcast or
multicast server, as in the <code>multicastclient</code> command with
default address. The default for this flag is disable.

<p><dt><code>monitor</code>
<dd>Enables the monitoring facility. See the <code>xntpdc</code> program
and the <code>monlist</code> command or further information. The default
for this flag is enable.

<p><dt><code>pll</code>
<dd>Enables the server to adjust its local clock by means of NTP. If
disabled, the local clock free-runs at its intrinsic time and frequency
offset. This flag is useful in case the local clock is controlled by
some other device or protocol and NTP is used only to provide
synchronization to other clients. In this case, the local clock driver
is used. See the <a href = "refclock.html">Reference Clock Drivers </a>
page for further information. The default for this flag is enable.

<p><dt><code>pps</code>
<dd>Enables the pulse-per-second (PPS) signal when frequency and time is
disciplined by the precision time kernel modifications. See the <a href
= "kern.html"> A Kernel Model for Precision Timekeeping </a> page for
further information. The default for this flag is disable.

<p><dt><code>stats</code>
<dd>Enables the statistics facility. See the <a href="monopt.html">
Monitoring Options </a>
page for further information. The default for this flag is enable.

<p><dt><code>pll_kernel</code>
<dd>When the precision time kernel modifications are installed, this
indicates the kernel controls the clock discipline; otherwise, the
daemon controls the clock discipline.

<p><dt><code>pps_kernel</code>
<dd>When the precision time kernel modifications are installed and a
pulse-per-second (PPS) signal is available, this indicates the PPS
signal controls the clock discipline; otherwise, the daemon or kernel
controls the clock discipline, as indicated by the
<code>pll_kernel</code> flag.

</dl>

<p><dt><code>restrict <i>address mask flag</i> [ <i>flag</i> ]</code>
<dd>This command operates in the same way as the <code>restrict</code>
configuration file commands of <code>xntpd</code>.

<p><dt><code>unrestrict <i>address mask flag</i> [ <i>flag</i> ]</code>
<dd>Unrestrict the matching entry from the restrict list.

<p><dt><code>delrestrict <i>address mask [ <i>ntpport</i> ]</i></code>
<dd>Delete the matching entry from the restrict list.

<p><dt><code>readkeys</code>
<dd>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 <code>xntpd</code> configuration file). This allows
encryption keys to be changed without restarting the server.

<p><dt><code>trustkey <i>keyid</i> [...]</code>
<br><dt><code>untrustkey <i>keyid</i> [...]</code>
<dd>These commands operate in the same way as the
<code>trustedkey</code> and <code>untrustkey</code> configuration file
commands of <code>xntpd</code>.

<p><dt><code>authinfo</code>
<dd>Returns information concerning the authentication module, including
known keys and counts of encryptions and decryptions which have been
done.

<p><dt><code>traps</code>
<dd>Display the traps set in the server. See the source listing for
further information.

<p><dt><code>addtrap [ <i>address</i> [ <i>port</i> ] [ <i>interface</i>
]</code>
<dd>Set a trap for asynchronous messages. See the source listing for
further information.

<p><dt><code>clrtrap [ <i>address</i> [ <i>port</i> ] [
<i>interface</i>]</code>
<dd>Clear a trap for asynchronous messages. See the source listing for
further information.

<p><dt><code>reset</code>
<dd>Clear the statistics counters in various modules of the server. See
the source listing for further information.

</dl>

<p><h4>Bugs</h4>

<p><code>xntpdc</code> 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.

<hr><address>David L. Mills (mills@udel.edu)</address></body></html>
