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)