NAME

       sntp - standard Simple Network Time Protocol program

SYNOPSIS

       sntp [-flag [value]]... [--opt-name [[=| ]value]]...
               [ hostname-or-IP ...]

DESCRIPTION

       This manual page briefly documents the sntp command.  sntp can be used as a SNTP client to
       query a NTP or SNTP server and either display the time or  set  the  local  system's  time
       (given suitable privilege).  It can be run as an interactive command or in a cron job.

       NTP  (the  Network  Time Protocol) and SNTP (the Simple Network Time Protocol) are defined
       and described by RFC 5905.

       The default is to write the estimated correct local date and time (i.e. not  UTC)  to  the
       standard  output in a format like '1996-10-15 20:17:25.123 (+0800) +4.567 +/- 0.089 secs',
       where the '(+0800)' means that to get to UTC from the reported local time one must  add  8
       hours  and  0  minutes, and the '+4.567 +/- 0.089 secs' indicates the local clock is 4.567
       seconds behind the correct time (so 4.567 seconds must be added to the local clock to  get
       it  to be correct), and the time of '1996-10-15 20:17:25.123' is believed to be correct to
       within +/- 0.089 seconds.

OPTIONS

       -4, --ipv4
              Force IPv4 DNS name resolution.  This option must not appear  in  combination  with
              any of the following options: ipv6.

              Force  DNS  resolution  of the following host names on the command line to the IPv4
              namespace.

       -6, --ipv6
              Force IPv6 DNS name resolution.  This option must not appear  in  combination  with
              any of the following options: ipv4.

              Force  DNS  resolution  of the following host names on the command line to the IPv6
              namespace.

       -d, --normalverbose
              Normal verbose.

              Diagnostic messages for non-fatal errors and a limited amount of tracing should  be
              written  to  standard  error.  Fatal ones always produce a diagnostic.  This option
              should be set when there is a suspected problem with the  server,  network  or  the
              source.

       -K file-name, --kod=file-name
              KoD history filename.

              Specifies  the filename to be used to persist the history of KoD responses received
              from servers.  The default is /var/db/ntp-kod.

       -p, --syslog
              Logging with syslog.  This option must not appear in combination with  any  of  the
              following options: logfile.

              When this option is set all logging will be done using syslog.

       -l file-name, --logfile=file-name
              Log  to  specified logfile.  This option must not appear in combination with any of
              the following options: syslog.

              This option causes the client to write log messages to the specified logfile.

       -s, --settod
              Set  (step)  the  time  with  settimeofday().   This  option  must  not  appear  in
              combination with any of the following options: adjtime.

       -j, --adjtime
              Set  (slew)  the  time  with adjtime().  This option must not appear in combination
              with any of the following options: settod.

       -b broadcast-address, --broadcast=broadcast-address
              Use broadcasts to the address specified for synchronisation.

              If  specified  SNTP  will  listen  to  the  specified  broadcast  address  for  NTP
              broadcasts.  The default maximum wait time, 68 seconds, can be modified with -t.

       -t seconds, --timeout=seconds
              Specify the number of seconds to wait for broadcasts.  This option takes an integer
              number as its argument.  The default seconds for this option is:
                   68

              When waiting for a broadcast packet SNTP will wait the number of seconds  specified
              before giving up.  Default 68 seconds.

       -a auth-keynumber, --authentication=auth-keynumber
              Enable  authentication  with  the key auth-keynumber.  This option takes an integer
              number as its argument.

              This option enables  authentication  using  the  key  specified  in  this  option's
              argument.   The  argument  of  this  option is the keyid, a number specified in the
              keyfile as this key's identifier. See the keyfile option (-k) for more details.

       -k file-name, --keyfile=file-name
              Specify a keyfile. SNTP will look in this file for the key specified with -a.

              This option specifies the keyfile. SNTP will search for the key specified  with  -a
              keyno in this file. Key files follow the following format:

              keyid keytype key

              Where     keyid  is  a  number identifying this key keytype is one of the follow: S
              Key in 64 Bit hexadecimal number as specified in in the DES specification.  N   Key
              in  64 Bit hexadecimal number as specified in the NTP standard.  A  Key in a 1-to-8
              character ASCII string.  M  Key in a 1-to-8 character ASCII string  using  the  MD5
              authentication scheme.

              For more information see ntp.keys(5).

       -?, --help
              Display extended usage information and exit.

       -!, --more-help
              Extended usage information passed thru pager.

       -> [rcfile], --save-opts[=rcfile]
              Save the option state to rcfile.  The default is the last configuration file listed
              in the OPTION PRESETS section, below.

       -< rcfile, --load-opts=rcfile, --no-load-opts
              Load options from rcfile.  The  no-load-opts  form  will  disable  the  loading  of
              earlier RC/INI files.  --no-load-opts is handled early, out of order.

       - [{v|c|n}], --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.

OPTION PRESETS

       Any  option  that  is  not  marked as not presettable may be preset by loading values from
       configuration ("RC" or ".INI") file(s) and values from environment variables named:
         SNTP_<option-name> or SNTP
       The environmental presets take precedence (are processed  later  than)  the  configuration
       files.   The homerc files are "$HOME", and ".".  If any of these are directories, then the
       file .ntprc is searched for within those directories.

USAGE

       The simplest use of this program is as an unprivileged command to check the  current  time
       and error in the local clock.  For example:

              sntp ntpserver.somewhere

       With  suitable  privilege,  it can be run as a command or in a cron job to reset the local
       clock from a reliable server, like the ntpdate and rdate commands.  For example:

              sntp -a ntpserver.somewhere

RETURN VALUE

       The program returns a zero exit status for success, and a non-zero one otherwise.

BUGS

       Please report bugs to http://bugs.ntp.org .

AUTHOR

       David L. Mills and/or others
       Please send bug reports to:  http://bugs.ntp.org, bugs@ntp.org

       see html/copyright.html

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

( 4.2.6p5)                                  2011-12-24                                    SNTP(1)