man > ntpkeygen(8)

NTPKEYGEN(8)                                   NTPsec                                   NTPKEYGEN(8)

NAME
       ntpkeygen - create and manage NTP host keys

SYNOPSIS
       ntpkeygen [-V]

DESCRIPTION
       This program generates a file containing keys that can be used in NTP’s symmetric key
       cryptography.

       The program produces a file containing ten pseudo-random printable ASCII strings suitable for
       the MD5 message digest algorithm. It also produces an additional ten hex-encoded random bit
       strings suitable for the SHA-1 and other message digest algorithms.

       The keys file must be distributed and stored using secure means beyond the scope of NTP
       itself. The keys can also be used as passwords for the ntpq <ntpq.html> utility program.

COMMAND LINE OPTIONS
       -V, --version
           Print the version string and exit.

RUNNING THE PROGRAM
       The simplest way to run the ntpkeygen program is logged in directly as root. The recommended
       procedure is to change to the keys directory, usually /etc/ntpsec/, then run the program.
       Then chown the output file to ntpsec:ntpsec. It should be mode 400.

           Warning

           ntpkeygen uses the system randomness source. On a POSIX system, this is usually
           /dev/urandom. Immediately after a reboot, on any OS, there may not be sufficient entropy
           available for this program to perform well. Do not run this program from any startup
           scripts. Only run this program on an active host with a lot of available entropy.

KEY FILE ACCESS AND LOCATION
       File names begin with the prefix ntpkey and end with the postfix hostname.filestamp, where
       hostname is the owner name, usually the string returned by the Unix gethostname() routine,
       and filestamp is the NTP seconds when the file was generated, in decimal digits.

       ntpkeygen also makes a soft link from ntp.keys to the generated file. ntp.keys is the normal
       file used in ntp.conf.

RANDOM SEED FILE
       All key generation schemes must have means to randomize the entropy seed used to initialize
       the internal pseudo-random number generator used by the library routines.

       It is important to understand that entropy must be evolved for each generation, for otherwise
       the random number sequence would be predictable. Various means dependent on external events,
       such as keystroke intervals can be used to do this and some systems have built-in entropy
       sources.

       This implementation uses Python’s random.SystemRandom class, which relies on os.urandom().
       The security of os.urandom() is improved in Python 3.5+
       <https://docs.python.org/library/os.html#os.urandom>.

CRYPTOGRAPHIC DATA FILES
       Unlike NTP Classic, this implementation generates only AES keys, not MD5 or SHA1.

       Since the file contains private shared keys, it should be visible only to root or ntp.

       In order to use a shared key, the line to be used must also be setup on the target server.

       This file is also used to authenticate remote configuration commands used by the ntpq(1)
       utility.

       Comments may appear in the file and are preceded with the # character.

       Following any headers the keys are entered one per line in the format:
       ┌───────┬───────────────────────────────────┐
       │       │                                   │
       │ Field │ Meaning                           │
       ├───────┼───────────────────────────────────┤
       │       │                                   │
       │ keyno │ Positive integer in the range     │
       │       │ 1-65,535                          │
       ├───────┼───────────────────────────────────┤
       │       │                                   │
       │ type  │ Type of key (MD5, SHA-1, AES-CMAC │
       │       │ etc). This program generates only │
       │       │ AES.                              │
       ├───────┼───────────────────────────────────┤
       │       │                                   │
       │ key   │ the actual key, printable ASCII   │
       │       │ or hex                            │
       └───────┴───────────────────────────────────┘


EXIT STATUS
       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.

NTPsec                                       2024-04-01                                 NTPKEYGEN(8)