MessPC Ethernetbox 2 and Nagios

As I talked to Tobi yesterday, we came to talk about our Ethernet Box thermometer. It’s a neat device, which works pretty much out of the box. Integrating it with Nagios is a bit of a bummer.

Ethernetbox 2
Ethernet box 2

That’s what the ~300 EUR box looks like. It’s basically a small black box with a RJ45 jack, and four RJ11 jacks for attached external devices. The box itself only functions as a “management station” and doesn’t come with a sensor.
Normally, you can attach up till four RJ11 sensors to it. But, MessPC also has RJ11 port splitters, which enables you to attach up to eight RJ11 sensors to the MessPC.

Thermometer RJ45 jacks
Thermometer RJ45 jacks

As you can see, the box has a RJ45 jack on the other side, which you basically hook up to your network and then configure an IP address (or if you fancy DHCP for those things, it’s possible too).

Thermometer RJ11 jacks
Thermometer RJ11 jacks

On the opposite site, are the RJ11 jacks for the sensors. As you can see, we currently do have 4 splitters attachted to the box, enabling up till 8 sensors to be measured.
Once you have it up and running, you can look at the web interface and you’ll be able to see the state of the sensors right on the first page.
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Nagios 3.x and

Recently we purchased a MessPC station for our server room, and my co-worker and myself had the wish it to be integrated within Nagios. Well, so far so good. The first I did was put both keywords into Google.

That pretty fast brought up the manufacturer’s page (sorry it’s German only) about the device supporting Nagios by means of either SNMP or a specific plugin called pcmeasure. So I went ahead and tried both ways.

Using SNMP has the advantage that it’s quickly integrated into Nagios and it doesn’t need a separate plugin for that to work. But it also has a huge disadvantage. check_snmp doesn’t support performance data, which is quite handy if you do want to do graphing from Nagios’ results.

Next I tried the pcmeasure plugin. At first it worked great (that is from plain command line), but then I tried to integrate it into Nagios (well, I did integrate it); but got “Plugin did not exit properly”.

Today, after I had the plugin commented out for about two weeks, I finally had time to look at the issue again. First I thought, simply using’s error values would be sufficient for ePN to quit yapping, but apparently it had *real* problems with the pod2usage used within.

So I basically rewrote the plugin (well, not really; it’s still the same – but without the pod2usage and working in Nagios 3.0.3).