Linux 2.6 - man page for ntpdc (linux section 1)
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ntpdc - special NTP query program
ntpdc [-ilnps] [-c command] [host] [...]
ntpdc is used to query the ntpd 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 specified at run time using ntpdc.
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. ntpdc will prompt for commands if the standard input is a termi-
ntpdc uses NTP mode 7 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. ntpdc 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 daemon
and can be expected to work only with this and maybe some previous versions of the daemon.
Requests from a remote ntpdc 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.
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 resolu-
tion 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.
-4 Force DNS resolution of following host names on the command line to the IPv4 names-
-6 Force DNS resolution of following host names on the command line to the IPv6 names-
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 standard 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 summary of their state.
This is equivalent to -c peers.
-s 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 -c
/usr/share/doc/ntp-doc/html/ntpdc.html for the full documentation.
Network Time Protocol October 7, 2006 NTPDC(1)
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