Provided by: ntp_4.2.6.p2+dfsg-1ubuntu12_i386 bug

NAME

       ntpd - Network Time Protocol (NTP) daemon

SYNOPSIS

       ntpd  [ -46aAbgLmnNqx ] [ -c conffile ] [ -f driftfile ] [ -i jaildir ]
       [ -k keyfile ] [ -l logfile ] [ -p pidfile ]  [  -P  priority  ]  [  -r
       broadcastdelay  ]  [  -s statsdir ] [ -t key ] [ -u user[:group] ] [ -U
       interface_update_interval ] [ -v variable ] [ -V variable ]

DESCRIPTION

       The ntpd program is an operating system daemon which sets and maintains
       the  system  time  of  day  in  synchronism with Internet standard time
       servers.  It is a complete implementation of the Network Time  Protocol
       (NTP)  version  4,  but  also  retains compatibility with version 3, as
       defined by RFC-1305, and version 1 and 2, as defined  by  RFC-1059  and
       RFC-1119,   respectively.    ntpd  does  most  computations  in  64-bit
       floating-point arithmetic and does relatively clumsy 64-bit fixed-point
       operations  only  when  necessary  to  preserve the ultimate precision,
       about 232 picoseconds.  While the ultimate precision is not  achievable
       with  ordinary  workstations  and networks of today, it may be required
       with future gigahertz CPU clocks and gigabit LANs.

       The daemon can operate in any of  several  modes,  including  symmetric
       active/passive,  client/server  broadcast/multicast  and  manycast.   A
       broadcast/multicast or manycast client  can  discover  remote  servers,
       compute   server-client   propagation   delay  correction  factors  and
       configure itself automatically.  This makes it  possible  to  deploy  a
       fleet of workstations without specifying configuration details specific
       to the local environment.

       Ordinarily, ntpd reads the ntp.conf configuration file at startup  time
       in  order to determine the synchronization sources and operating modes.
       It  is  also  possible  to  specify   a   working,   although   limited
       configuration  entirely  on  the command line, obviating the need for a
       configuration file.  This may  be  particularly  appropriate  when  the
       local  host  is  to  be  configured  as a broadcast/multicast client or
       manycast client, with  all  peers  being  determined  by  listening  to
       broadcasts at run time.

       Various  internal  ntpd  variables  can  be displayed and configuration
       options altered while the daemon is running using  the  ntpq  and  ntpd
       utility programs.

       When ntpd starts it looks at the value of umask, and if it is zero ntpd
       will set the umask to 0222.

OPTIONS

       -a     Require  cryptographic  authentication  for  broadcast   client,
              multicast  client  and  symmetric passive associations.  This is
              the default.

       -A     Do  not  require  cryptographic  authentication  for   broadcast
              client,  multicast  client  and  symmetric passive associations.
              This is almost never a good idea.

       -b     Enable the client to synchronize to broadcast servers.

       -c conffile
              Specify the name and path of  the  configuration  file,  default
              /etc/ntp.conf.

       -f driftfile
              Specify  the  name  and  path  of  the  frequency  file, default
              /etc/ntp.drift.  This is the same  operation  as  the  driftfile
              driftfile configuration command.

       -g     Normally,  ntpd  exits  with  a message to the system log if the
              offset exceeds the panic threshold, which is 1000 s by  default.
              This  option  allows  the  time  to  be set to any value without
              restriction;  however,  this  can  happen  only  once.   If  the
              threshold  is exceeded after that, ntpd will exit with a message
              to the system log.  This option can be used with the -q  and  -x
              options.

       -i jaildir
              Chroot  the  server  to the directory jaildir.  This option also
              implies that the server attempts  to  drop  root  privileges  at
              startup   (otherwise,   chroot   gives  very  little  additional
              security).  You may need to also specify a -u option.

       -I [address | interface name]
              Open the network address given, or all the addresses  associated
              with  the given interface name.  This option may appear multiple
              times.  This option also implies not  opening  other  addresses,
              except  wildcard  and  localhost.   This  option  is deprecated.
              Please consider using the configuration file interface  command,
              which is more versatile.

       -k keyfile
              Specify  the  name  and  path of the symmetric key file, default
              /etc/ntp.keys.  This is the same operation as the  keys  keyfile
              configuration command.

       -l logfile
              Specify  the  name and path of the log file.  The default is the
              system log file.  This is the  same  operation  as  the  logfile
              logfile configuration command.

       -L     Do not listen to virtual IPs.  The default is to listen.

       -n     Don't fork.

       -N     To the extent permitted by the operating system, run the ntpd at
              the highest priority.

       -p pidfile
              Specify the name and path of the file used to  record  the  ntpd
              process  ID.   This is the same operation as the pidfile pidfile
              configuration command.

       -P priority
              To the extent permitted by the operating system, run the ntpd at
              the specified priority.

       -q     Exit  the ntpd just after the first time the clock is set.  This
              behavior mimics that of the ntpdate  program,  which  is  to  be
              retired.   The  -g  and -x options can be used with this option.
              Note: The kernel time discipline is disabled with this option.

       -r broadcastdelay
              Specify    the    default    propagation    delay    from    the
              broadcast/multicast  server  to  this client.  This is necessary
              only if the  delay  cannot  be  computed  automatically  by  the
              protocol.

       -s statsdir
              Specify  the  directory path for files created by the statistics
              facility.  This is the same operation as the  statsdir  statsdir
              configuration command.

       -t key Add a key number to the trusted key list.  This option can occur
              more than once.

       -u user[:group]
              Specify a user, and optionally a group, to switch to.

       -U interface_update_interval
              Number of seconds to wait between interface list scans  to  pick
              up  new  and  delete  network  interface.   Set  to 0 to disable
              dynamic interface list updating.  The default is to scan every 5
              minutes.

       -v variable, -V variable
              Add a system variable listed by default.

       -x     Normally, the time is slewed if the offset is less than the step
              threshold, which is 128 ms by default, and stepped if above  the
              threshold.   This  option  sets the threshold to 600 s, which is
              well within the accuracy  window  to  set  the  clock  manually.
              Note:  Since the slew rate of typical Unix kernels is limited to
              0.5 ms/s, each second of  adjustment  requires  an  amortization
              interval  of  2000 s.  Thus, an adjustment as much as 600 s will
              take almost 14 days to complete.  This option can be  used  with
              the  -g  and  -q  options.   Note: The kernel time discipline is
              disabled with this option.

FILES

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

       /etc/ntp.drift
              default name of the drift file

SEE ALSO

       ntp.conf(5), ntpdate(8)

       The     complete      documentation      can      be      found      at
       /usr/share/doc/ntp-doc/html/ntpd.html in the package ntp-doc.