make ntp-reconfigure
make ntp-rebuild

cp -f /usr/share/zoneinfo/Asia/Shanghai /etc/localtime

ntpd -g

tcpdump port 123 -vvv

ntpd - NTP daemon program - Ver. 4.2.8p10
Usage:  ntpd [ -<flag> [<val>] | --<name>[{=| }<val>] ]... \
    [ <server1> ... <serverN> ]
  Flg Arg Option-Name    Description
   -4 no  ipv4           Force IPv4 DNS name resolution
        - prohibits the option 'ipv6'
   -6 no  ipv6           Force IPv6 DNS name resolution
        - prohibits the option 'ipv4'
   -a no  authreq        Require crypto authentication
        - prohibits the option 'authnoreq'
   -A no  authnoreq      Do not require crypto authentication
        - prohibits the option 'authreq'
   -b no  bcastsync      Allow us to sync to broadcast servers
   -c Str configfile     configuration file name
   -d no  debug-level    Increase debug verbosity level
        - may appear multiple times
   -D Num set-debug-level Set the debug verbosity level
        - may appear multiple times
   -f Str driftfile      frequency drift file name
   -g no  panicgate      Allow the first adjustment to be Big
        - may appear multiple times
   -G no  force-step-once Step any initial offset correction.
   -i --- jaildir        built without --enable-clockctl or --enable-linuxcaps or --enable-solarisprivs
   -I Str interface      Listen on an interface name or address
        - may appear multiple times
   -k Str keyfile        path to symmetric keys
   -l Str logfile        path to the log file
   -L no  novirtualips   Do not listen to virtual interfaces
   -n no  nofork         Do not fork
        - prohibits the option 'wait-sync'
   -N no  nice           Run at high priority
   -p Str pidfile        path to the PID file
   -P Num priority       Process priority
   -q no  quit           Set the time and quit
        - prohibits these options:
        saveconfigquit
        wait-sync
   -r Str propagationdelay Broadcast/propagation delay
      Str saveconfigquit Save parsed configuration and quit
        - prohibits these options:
        quit
        wait-sync
   -s Str statsdir       Statistics file location
   -t Str trustedkey     Trusted key number
        - may appear multiple times
   -u --- user           built without --enable-clockctl or --enable-linuxcaps or --enable-solarisprivs
   -U Num updateinterval interval in seconds between scans for new or dropped interfaces
      Str var            make ARG an ntp variable (RW)
        - may appear multiple times
      Str dvar           make ARG an ntp variable (RW|DEF)
        - may appear multiple times
   -w Num wait-sync      Seconds to wait for first clock sync
        - prohibits these options:
        nofork
        quit
        saveconfigquit
   -x no  slew           Slew up to 600 seconds
   -m no  mdns           Register with mDNS as a NTP server
      opt version        output version information and exit
   -? no  help           display extended usage information and exit
   -! no  more-help      extended usage information passed thru pager
Options are specified by doubled hyphens and their name or by a single
hyphen and the flag character.
The following option preset mechanisms are supported:
 - examining environment variables named NTPD_*
Please send bug reports to:  <http://bugs.ntp.org, bugs@ntp.org>

/etc/init.d/S49ntp stop
/etc/init.d/S49ntp start