because I lose too much time figuring out how to use complex snmpwalk/snmpget SNMP to get vital data like CPU usage, disk usage and other stuff in my MRTG reporting. I want something easy to install, easy to use, easy to understand. Like a URL with easy, readable parameters.

The MRTG sensor can be used to monitor a number of different variables. The PHP process will execute a PHP own command, or will run a bash command line to get the data. All these sensors are READ-ONLY. Never can a root-level (sudo) command be required to get the data.

• cpu usage (uses the top command)
• memory usage (uses the free command)
• disk usage (uses the df command)
• folder size in MB/GB(uses the du command)
• file count/folder count (uses the lscommand)
• (more to be added)

• the server you want to monitor should have a webserver that can run PHP
• the web service can be called over a LAN ( 192.168.1.___/mrtg_sensor/ ) or over the internet ( www.example.com/mrtg_sensor/ )
• the web service can obviously be called locally too ( localhost:8080/mrtg_sensor/ )

• install this folder on the server you want to monitor (eg server01)
• in the MRTG config of your MRTG client (standard name: mrtg.cfg ), use curl to get the output of the script

An example:

the script will return with the standard 4 text lines that MRTG requires:

1. value I
2. value O (optional)
3. uptime
4. hostname

and will add some more lines (which are ignored by MRTG):

5. the URL for configuring

or, when the URL for configuring is used

6. the full MRTG to be used:
   • Target
   • Title
   • PageTop
   • Legend
   • ShortLegend
   • Options

Example: