Passive freshness checks -> active checks

[Charlie Reddington]

> I can't see any problem with the config below.  If you have dozens of
> checks set up this way and they are all set up in crontab to run at
> */15 then you will get a storm of checks at each 15 minute intervals.
> I normally make sure I stagger the checks in cron so that they are
> reasonably evenly spaced.  If you have thousands it might also be
> worth introducing a small random sleep to spread them out even more.
>
> I've not had any problems with it myself, but if you have a very busy
> system, you might need to check that the command buffers aren't
> filling (run /usr/local/nagios/bin/nagiosstats to list the current
> Nagios statistics).
>
> Check the logs from nsca too.  If I recall correctly you may need to
> set debug=1 in nsca.cfg for a while to get enough information.  One
> problem I sometimes see occurs when the clock on the sending server is
> way out of sync with the clock on the Nagios server, nsca will
> complain and not process the check.  See this section in the nsca.cfg
> file:
>
>  # MAX PACKET AGE OPTION
>  # This option is used by the nsca daemon to determine when client
>  # data is too old to be valid.  Keeping this value as small as
>  # possible is recommended, as it helps prevent the possibility of
>  # "replay" attacks.  This value needs to be at least as long as
>  # the time it takes your clients to send their data to the server.
>  # Values are in seconds.  The max packet age cannot exceed 15
>  # minutes (900 seconds).  If this variable is set to zero (0), no
>  # packets will be rejected based on their age.
>
>  max_packet_age=30
>
> If I recall, I increased this from some smaller value to make it more
> forgiving of systems which are a bit out of sync.
>
>
> I hope that's pointed you in the right direction.
>
> Cheers,
>
> Jim

Hey Jim,

Thanks for the info,

I have increased the time offset to be a minute or two. But all our  
systems should be close as we use NTP to keep them in sync, and nagios  
currently does active checks on this one to make sure things are happy.

I'll check out the stats and turn on debugging next to see if there is  
anything there. In the mean time, what version of nagios are you  
running?

Thanks,

Charlie

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