Time server...how to set it up on FC1?

[Tom 'Needs A Hat' Mitchell]

On Mon, Apr 12, 2004 at 10:39:16PM -0600, Rodolfo J. Paiz wrote:
> 
> At 22:32 4/12/2004, you wrote:
> >The new ntpdate will no longer make the brutal abrupt time adjustment
> >that some of us got to know and 'love'.  I am not sure which behavior
> >is in the FC1/2 ntp package at this time but the "time"s they be a changing
> >on this point.
> >
> >Read all about it on the ntp home pages and in the Fedora archives.
> 
> Most interesting. The last thing I read on the subject was a huge diatribe 
> on the evils of ntpdate.
......

> Haven't had much time to STFW here, but can you point me to a URL or two?

  http://www.eecis.udel.edu/~mills/ntp/html/ntpdate.html

 ...."The functionality of this program is now available in the ntpd
 program. See the -q command line option in the ntpd - Network Time
 Protocol (NTP) daemon page. After a suitable period of mourning, the
 ntpdate program is to be retired from this distribution"....
                                                                                
       -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.

       -g      Normally, ntpd  exits if the offset exceeds the  sanity  limit,
               which is 1000 s by default. If the sanity limit is set to zero,
               no sanity checking is performed and any offset  is  acceptable.
               This  option  overrides the limit and allows the time to be set
               to any value without restriction; however, this can happen only
               once.   After  that,  ntpd  will exit if the limit is exceeded.
               This option can be used with the -q  option.
             
       -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 forces the time to be slewed
               in all cases. If the step threshold is set to zero, all offsets
               are  stepped,  regardless  of  value  and  regardless of the -x
               option. In general, this is not a good idea, as it bypasses the
               clock  state  machine which is designed to cope with large time
               and frequency errors Note: Since the slew rate  is  limited  to
               0.5  ms/s,  each  second of adjustment requires an amortization
               interval of 2000 s. Thus, an adjustment  of  many  seconds  can
               take  hours  or  days to amortize. This option can be used with
               the -q  option.
 


But not all sources of time are ntp...
So here is one idea to get folks jumping up and down.....

In a pinch one can force the time in a brutal way.
Find a host that returns the correct time of day.

    $ telnet 192.168.0.51 13
    Trying 192.168.0.51...
    Connected to (192.168.0.51).
    Escape character is '^]'.
    12 APR 2004 22:03:13 PDT
    Connection closed by foreign host.

this can be cleaned up a  bit
   frog=`telnet 192.168.0.51 13| grep ^[0-9]`
   echo $frog

The system date date can be set with 'date'.  A little script magic to
do some sanity checking, translate month to a number etc. and get the
instant 'good time' that some people like.

   # date [-u|--utc|--universal] [MMDDhhmm[[CC]YY][.ss]]
   
It might better to do something like this first and
find out if there is value in all this.

   frog=`telnet 192.168.0.51 13| grep ^[0-9]`
   logger "Time at   192.168.0.51 is $frog"

Now an inspection of var/log/messages will tell you if you really want to 
play with this stuff.

Apr 12 22:18:29 box1 bob: Time at   192.168.0.51 is 12 APR 2004 22:18:29 PDT
Apr 12 22:18:31 box1 bob: Time at   192.168.0.51 is 12 APR 2004 22:18:31 PDT
Apr 12 22:18:32 box1 bob: Time at   192.168.0.51 is 12 APR 2004 22:18:32 PDT

Other 'services' can be abused... which is why most are turned off.
    $ grep time /etc/services
    daytime         13/tcp


   ;-)


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