Network Time Protocol

Resources  edit

Network Time Protocol Project

distributes Davi Mills' NTPD implementation

Documentation  edit

RFC 5905, Network Time Protocol Version 4: Protocol and Algorithms Specification, 2010-06

RFC 4330, Simple Network Time Protocol (SNTP) Version 4 for IPv4, IPv6 and OSI, 2006-01

RFC 868, Time Protocol, 1983-05

RFC 867, Daytime Protocol, 1983-05

Documentation page, NTP Project

Tools  edit

AboutTime

an excellent and free time client for Windows

Description  edit

package require time
proc NetTime {server} {
    set tok [time::getsntp $server] ;# or gettime to use the TIME protocol
    time::wait $tok
    if {[time::status $tok] eq {ok}} {
         set result [time::unixtime $tok]
         set code ok
    } else {
         set result [time::error $tok]
         set code error
    }
    time::cleanup $tok
    return -code $code $result
}

clock format [NetTime ntp.blueyonder.co.uk]

set newtime [clock format $seconds -format %H.%M.%S]
exec cmd /c "echo $newtime | time"
puts "set time to $newtime"
set newdate [clock format $seconds -format %m/%d/%Y]
exec cmd /c "echo $newdate | date"
puts "set date to $newdate"

##
## good-time - for the correct time, ...
##
## Placed into the public domain by rec@elf.org, January 1999.
##
## usage: good-time [host [port [timezone]]]
##     host - defaults to time.nist.gov.
##     port - defaults to 13.
##     timezone - defaults to nothing, not necessary for NIST format.
##
## After wading through a complicated linux time synchronization
## package, it turned out that the key was to telnet to time.nist.gov
## on port 13.  You can do that in tcl, so here it is.
##
## It also turns out that a lot of machines return some kind of time
## service on port 13, so I recognize a few variations in the format
## returned.
##
## See http://www.boulder.nist.gov/timefreq/ for more information and
## links to yet more information.
##
# 23Jan02RT - add -set flag
set doset 0
if {$argc >= 1 && [string equal [lindex $argv 0] -set]} {
    incr argc -1
    set argv [lrange $argv 1 end]
    set doset 1
}

##
## choose the host
##

# 11Jan02RT TODO use host list
# numeric values come from "Atomic Clock Sync v2.5" server menu
set hlist {
    129.6.15.28         
    129.6.15.29         
    132.163.4.101       
    132.163.4.102       
    132.163.4.103       
    128.138.140.44      
    time-nw.nist.gov
    time-a.timefreq.bldrdoc.gov
    time.nist.gov
    allhoststried
}

# set host time.nist.gov
if {$argc > 0} {
    set hlist [concat[lindex $argv 0] $hlist]
}

##
## choose the port
##
set port 13
if {$argc > 1} {
    set port [lindex $argv 1];
}

##
## choose the timezone
##
set timezone {}
if {$argc > 2} {
    set timezone [lindex $argv 2];
}

##
## set a time out
##
after [expr 30*1000] {
    close $sock
    puts stderr {timed out}
    if {[info exists lines]} {
       puts stderr "no time found in:\n$lines"
    }
    exit 1;
}

##
## open a socket
##
foreach h $hlist {
    if {[catch {socket $h $port} sock]} {
        #puts stderr "socket: $sock"
        #exit 2;
        puts stderr "host $h - FAILED"
        continue
    }
    break
}

##
## read what comes back
##
while {[gets $sock line] >= 0} {
    # typical daytime response is unix date format without timezone indication
    #
    #  Mon Sep 16 21:59:22 1996

    set seconds 0
    if {[regexp \
        {^... ([A-Z][a-z][a-z]) ([ \d]\d) (\d\d:\d\d:\d\d) (\d\d\d\d)$} \
        $line all month mday time year]} {
        set seconds [clock scan "$month $mday, $year $time $timezone"]
    }

    #
    # NIST time service format returned by:
    #
    #  time.nist.gov
    #  time-nw.nist.gov
    #  time-a.timefreq.bldrdoc.gov
    #
    # 50343 96-09-17 05:02:07 50 0 0  50.0 UTC(NIST) * 
    #
    if {!$seconds &&
        [regexp \
            {^..... (\d\d)-(\d\d)-(\d\d) (\d\d:\d\d:\d\d) .. . . ..... UTC\(NIST\)} \
     $line all year month day time]} {
       set seconds [clock scan "$month/$day/$year $time UTC"]
    }

    #
    # USNO master clock format returned by:
    #
    #  tick.usno.navy.mil
    #  tock.usno.navy.mil
    #
    # 50343 261 044932 UTC
    #
    if {!$seconds && [regexp {^..... ([ \d][ \d]\d) (\d\d)(\d\d)(\d\d) UTC$} \
            $line all doy hour minute second]} {
       set seconds [clock scan $hour:$minute:$second -gmt true]
    }
    if {$seconds} {
       puts "FETCHED: [clock format $seconds]"
       puts "  LOCAL: [clock format [clock seconds]]"
       if {$doset} {
           # JJM 5/12/2003 -- added missing "." in between %H and %M.
           set newtime [clock format $seconds -format %H.%M.%S]
           exec date.exe $newtime
           puts "set date to $newtime"
       }
       close $sock;
       exit 0;
   }
    
    #
    # save unrecognized stuff for final error message
    #
    append lines $line\n
}

##
## give up
##
close $sock;
puts stderr "no time found in:\n$lines";
exit 4

TIME protocol client  edit

868

proc TIMEseconds {host} {
    set c -2208988800        ;# epoch-shifter: 1970-1900 in seconds
    set s [socket $host 37]  ;# 37 is TIME
    fconfigure $s -translation binary
    set r [read $s]
    close $s
    binary scan $r I t       ;# "I" is uppercase i, not lowercase L
    incr t $c
}

puts [clock format [TIMEseconds $myTIMEserver]]

Setting the system clock  edit

exec cmd.exe /c time [clock format [
    TIMEseconds $myTIMEserver] -format %H:%M:%S]

package require registry
set fmt [
    registry get {HKEY_CURRENT_USER\Control Panel\International} sShortDate]
foreach e {d m y} {regsub -nocase $e+ $fmt %$e fmt}
exec cmd.exe /c date [clock format [TIMEseconds $myTIMEserver] -format $fmt]

exec cmd.exe ...

eval exec [auto_execok date] ...

Finding a TIME server  edit

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