check_ntp -- need a little bit help

[Subhendu Ghosh]

Would be interested in the patch.


On Wed, 6 Nov 2002, Schimpke, Dr. Thomas / bhn wrote:

> Hi all,
> 
> I've a couple of ntp servers/clients running. I wanted to check them with
> check_ntp, but got (almost always) the message "UNKNOWN: Dispersion too
> high". The dispersion is hard coded in the plugin to 15 (ms), the actual
> dispersion was much below. I was a little bit curios about this issue, so I
> looked at the source code and found, that check_ntp basically parses the
> output of the command xntpdc/ntpdc -s. Running "xntpdc -s hostname" resulted
> in an error message: "*** Server reports a format error in the received
> packet (shouldn't happen)". 
> 
> According to Dave Mills (see google...) there is *no gurantee* that xntpdc
> is interoperable between two releases of the ntp package. He recommands
> useing ntpq instead (xntpdc seems to exist mainly for debugging purposes). 
> 
> I've patched the plugin to use ntpq (basically I run ntpq -p, the dispersion
> is reported in the 10th field). This seems to work fine (if someone is
> intrested in a patch, drop me a note). The problem is, which peer to take
> from the output (you normally have several peers on a server/client running
> the ntp process). This  is not a ntpq issue -- you have the same problem, if
> you use xntpdc: you get a list of peers. If you do nothing about it, you get
> the dispersion of the last peer reported in the list (not good), in my case
> it's the LOCAL peer, which is unintresting. Instead the list should be
> processed according to the tally codes (the value in the first column of the
> list). But even then: do I take the sys.peer/pps.peer or the mean value of
> all peers used in the combine algorithm...
> 
> I'm not even sure, if the dispersion is a good measure of the ntp "state"
> for ntp configured as a client on a local network. The "offset" of the clock
> sems to be more appropriate, but I'm not a ntp specialist.
> 
> Any comments ?
> 
> Greetings,
> 
> Thomas
>  

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