Updated: 2021/Apr/14

NTP_KEYS(5)               File Formats Manual (file)               NTP_KEYS(5)

     ntp.keys - NTP symmetric key file format

     ntp.keys - NTP symmetric key file format

     ntp.keys [--option-name] [--option-name value]

              All arguments must be options.

     This document describes the format of an NTP symmetric key file.  For a
     description of the use of this type of file, see the "Authentication
     Support" section of the ntp.conf(5) page.

     ntpd(8) reads its keys from a file specified using the -k command line
     option or the keys statement in the configuration file.  While key number
     0 is fixed by the NTP standard (as 56 zero bits) and may not be changed,
     one or more keys numbered between 1 and 65535 may be arbitrarily set in
     the keys file.

     The key file uses the same comment conventions as the configuration file.
     Key entries use a fixed format of the form

           keyno type key opt_IP_list

     where keyno is a positive integer (between 1 and 65535), type is the
     message digest algorithm, key is the key itself, and opt_IP_list is an
     optional comma-separated list of IPs where the keyno should be trusted.
     that are allowed to serve time.  Each IP in opt_IP_list may contain an
     optional /subnetbits specification which identifies the number of bits
     for the desired subnet of trust.  If opt_IP_list is empty, any
     properly-authenticated message will be accepted.

     The key may be given in a format controlled by the type field.  The type
     MD5 is always supported.  If ntpd was built with the OpenSSL library then
     any digest library supported by that library may be specified.  However,
     if compliance with FIPS 140-2 is required the type must be either SHA or

     What follows are some key types, and corresponding formats:

     MD5     The key is 1 to 16 printable characters terminated by an EOL,
             whitespace, or a # (which is the "start of comment" character).

     RMD160  The key is a hex-encoded ASCII string of 40 characters, which is
             truncated as necessary.

     Note that the keys used by the ntpq(8) and ntpdc(8) programs are checked
     against passwords requested by the programs and entered by hand, so it is
     generally appropriate to specify these keys in ASCII format.

     --help  Display usage information and exit.

             Pass the extended usage information through a pager.

     --version [{v|c|n}]
             Output version of program and exit.  The default mode is `v', a
             simple version.  The `c' mode will print copyright information
             and `n' will print the full copyright notice.

     Any option that is not marked as not presettable may be preset by loading
     values from environment variables named:
       NTP_KEYS_<option-name> or NTP_KEYS

     See OPTION PRESETS for configuration environment variables.

     /etc/ntp.keys  the default name of the configuration file

     One of the following exit values will be returned:

     0  (EXIT_SUCCESS)
             Successful program execution.

     1  (EXIT_FAILURE)
             The operation failed or the command syntax was not valid.

     70  (EX_SOFTWARE)
             libopts had an internal operational error.  Please report it to
             autogen-users@lists.sourceforge.net.  Thank you.

     ntp.conf(5), ntpd(1ntpdmdoc), ntpdate(1ntpdatemdoc), ntpdc(1ntpdcmdoc),

     The University of Delaware and Network Time Foundation

     Copyright (C) 1992-2020 The University of Delaware and Network Time
     Foundation all rights reserved.  This program is released under the terms
     of the NTP license, <http://ntp.org/license>.

     Please send bug reports to: http://bugs.ntp.org, bugs@ntp.org

     This document was derived from FreeBSD.

     This manual page was AutoGen-erated from the ntp.keys option definitions.

FreeBSD 11.2-RELEASE_SI          March 3 2020          FreeBSD 11.2-RELEASE_SI