SNMP "bridging"/proxy?

Eric Kuhnke eric.kuhnke at gmail.com
Mon May 23 21:44:16 UTC 2016


Thinking of the recent conversation on ntp daemon precision and reliability
here on nanog, reminded me of:

https://www.pitt-pladdy.com/blog/_20140826-094101_0100_NTP_Monitoring_on_Cacti_over_SNMP/

There's a tiny shell script linked there on github which does nothing more
than run "ntpq -p" on your ntpd and parse the results of the 9th and 10th
columns (jitter an offset) into milliseconds. On a typical debian system
you'll need to install the 'bc' package for command line calculations.

Of course no need to use Cacti, though the XML template is ready to use.
You can use the newly exposed OIDs via SNMP with opennms or some other
charting/graphing system, or even something totally non RRA/RRDtool based
such as collectd and a time series database for long term storage of data
on a 60-second poller interval.


Another thing you can do with 'extend' is monitor an openvpn daemon.
There's no built in SNMP support in openvpn but it can be configured to
listen for a management CLI on localhost. Run tiny shell, perl or python
scripts that do something as simple as parse the openvpn-status.log, spit
out the list of currently active clients, pipe that into a one line script
with sed and "wc -l", feed the integer into a SNMP charting/monitoring
system.



On Mon, May 23, 2016 at 2:13 PM, Wes Hardaker <wjhns61 at hardakers.net> wrote:

> Eric Kuhnke <eric.kuhnke at gmail.com> writes:
>
> > http://www.adventuresinoss.com/2009/09/30/the-many-uses-of-net-snmp/
>
> Ha!  I've never seen that article, thanks for pointing it out.
>
> Note that the performance of Net-SNMP's extensibility mechanisms should
> way into the decision.  The fastest backend needs to be written in C,
> and embedded perl is an easy second.  Beyond that, pass_persist is
> somewhere in the middle and pass/extend/other execs are the slowest
> because of the need to exec a command for every incoming request which
> is expensive.  Great for bootstrapping and testing, but in the long run
> look to the better coding solutions.
>
> Tutorials for most of these exist:
>
>    http://www.net-snmp.org/wiki/index.php/Tutorials#Coding_Tutorials
>
>
> [as a point of history: Net-SNMP has always been very extensible since
> it was started based on my need to add extensibility to an agent way
> back in 1995-ish in order to monitor some special cases on a map with HP
> OV (as it was known back then)]
> --
> Wes Hardaker
> My Pictures:       http://capturedonearth.com/
> My Thoughts:       http://blog.capturedonearth.com/
>


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