[HOWTO] Install MRTG SNMP Monitoring Inside Jail

[Snunn1]

[HOWTO] Install MRTG SNMP Monitoring Inside Jail

Tested on:
NAS4Free 9.1.0.1 - Sandstorm (rev 804 & 847)
Platform x64-Embedded on 512MB USB Flash Stick on HP Microserver N40L (AMD64)
Works on Apache 2.2 and 2.4 without additional configuration

This guide will detail how to install MRTG in a jail to monitor SNMP-enabled devices. This will require no previous experience or knowledge of MRTG, SNMP or Apache and will consist of as minimal configuration as possible to get you started. There will always be other, better ways in doing most of this however the methods outlined here have worked for me and should minimise any confusion/frustration.

This guide assumes you have a system running a default installation of N4F with the IP address 192.168.1.250. This server has a new jail called 'mrtg' with an IP address of 192.168.1.251, has fully working Internet access, SSH and a file editor (Nano).

Before I begin, the sources I give credit to are the following:

Alexey123's SNMP + MRTG on Nas4free
Tobi Oetiker's MRTG Homepage

To start with, we need to enable SNMP on the server so we've got something for MRTG to communicate with. To do this, go to Services -> SNMP and enable it as per the following screenshot:

N4F - SNMP.jpg

Once complete, SSH into your server and list the jails:

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Welcome to NAS4Free!
nas4free: ~ # jls
   JID  IP Address      Hostname                      Path
     1  192.168.1.251   mrtg.domain.local            /jail/mrtg

Then enter the jail:

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nas4free: ~ # jexec 1 csh
root@mrtg:/ #

Once in the jail, check the hosts file:

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root@mrtg:/ # cat /etc/hosts
::1 localhost localhost.local
127.0.0.1 localhost localhost.local
192.168.1.250 nas4free nasfree.local

If it doesn't look like the above, enter the following

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echo '192.168.1.250 nasfree nas4free.local' >> /etc/hosts

Next, the necessary packages or ports need to be installed, this guide will outline the procedure for both.

To start with, enter one of the two commands below depending on whether your system is AMD or Intel based:

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setenv PACKAGESITE "ftp://ftp.freebsd.org/pub/FreeBSD/ports/amd64/packages-9-current/Latest/"

setenv PACKAGESITE "ftp://ftp.freebsd.org/pub/FreeBSD/ports/i386/packages-9-current/Latest/"

If you want to use the FreeBSD Ports Collection, install it with the following commands:

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portsnap fetch extract

If it's already installed, make sure it's up to date:

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portsnap fetch update

Next, install the NET-SNMP port:

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cd /usr/ports/net-mgmt/net-snmp/
make install clean

If you're using packages:

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pkg_add -r net-snmp

Do the same with Apache 2.2, again using ports:

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cd /usr/ports/www/apache22
make install clean

And with packages:

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pkg_add -r apache22

And finally, install MRTG:

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cd /usr/ports/net-mgmt/mrtg/
make install clean

And with packages:

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pkg_add -r mrtg

Once these are installed by either method, enter the following:

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mkdir /usr/local/www/apache22/data/mrtg
touch /var/log/mrtg.log
chown -R mrtg:mrtg /usr/local/etc/mrtg /usr/local/www/apache22/data/mrtg /var/log/mrtg.log

Next, we need to create the configuration file which MRTG will refer to. This will probe the system specified in the command below and output information on the interfaces which it finds. The 'LoadMIBs' line will enable MRTG to graph CPU, memory etc.

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cfgmaker --global 'WorkDir: /usr/local/www/apache22/data/mrtg' --global 'Options[_]: growright,unknaszero,transparent,bits' --global  'RunAsDaemon: Yes' --global 'LoadMIBs: /usr/local/share/snmp/mibs/UCD-SNMP-MIB.txt' --output /usr/local/etc/mrtg/mrtg.cfg public@192.168.1.250

Once complete, the next command will create an index.html file for Apache based on your configuration file:

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/usr/local/bin/indexmaker /usr/local/etc/mrtg/mrtg.cfg > /usr/local/www/apache22/data/mrtg/index.html

Then, all you need to do is start Apache if it hasn't been already:

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/usr/local/etc/rc.d/apache22 start

And run the MRTG daemon:

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env LANG=C /usr/local/bin/mrtg --logging /var/log/mrtg.log --user mrtg --group mrtg --daemon /usr/local/etc/mrtg/mrtg.cfg

The result will be:

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2013-10-29 21:48:16 -- Started mrtg with config '/usr/local/etc/mrtg/mrtg.cfg'
Daemonizing MRTG ...

To test it, enter http://192.168.1.251/mrtg into your browser and the index page should show up. Click on the graph to give you more graphs showing usage on a daily/weekly/monthly/yearly basis:

N4F - LAN.jpg

If you want to run Apache and the MRTG daemon automatically each time the jail starts, enter the following:

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echo 'mrtg_daemon_enable="YES"' >> /etc/rc.conf
echo 'apache22_enable="YES"' >> /etc/rc.conf

And that's it! Pretty straightforward and there's still plenty of other things you could graph. If, for example, you want to graph your Active CPU Load in percentage, enter the following at the bottom of the mrtg.cfg file:

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# CPU Load - NAS4Free
Target[nas4free_cpu]:1.3.6.1.4.1.2021.10.1.3.1&1.3.6.1.4.1.2021.10.1.3.1:public@192.168.1.250:*100
Options[nas4free_cpu]: growright,gauge,noo,nolegend,unknaszero,transparent
RouterUptime[nas4free_cpu]: public@192.168.1.250
Kilo[nas4free_cpu]: 100
MaxBytes[nas4free_cpu]: 100
Unscaled[nas4free_cpu]: dwmy
ShortLegend[nas4free_cpu]: %
YLegend[nas4free_cpu]: Active CPU Load % - NAS4Free
Title[nas4free_cpu]: CPU Load - NAS4Free
PageTop[nas4free_cpu]: <H1>Active CPU Load % - NAS4Free</H1>

Run the indexmaker command again to update index.html and it will start to look like this:

N4F - CPU and LAN.jpg

For details on measuring CPU, disk temperature and others, see the post below:

Alexey123's SNMP + MRTG on Nas4free

I hope some of you find this guide useful, any corrections or recommendations are welcome.