Error did not find any matching data in cfg file

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The Multi Router Traffic Grapher (MRTG) is a tool to monitor the traffic load on network links. MRTG generates HTML pages containing PNG images which provide a LIVE visual representation of this traffic.

MRTG Features

Portable

MRTG works on most UNIX platforms and Windows NT.

Perl

MRTG is written in Perl and comes with full source.

Portable SNMP

MRTG Uses a highly portable SNMP implementation written entirely in Perl (thanks to Simon Leinen). There is no need to install any external SNMP package.

SNMPv2c support

MRTG can read the new SNMPv2c 64bit counters. No more counter wrapping.

Reliable Interface Identification

Router interfaces can be identified by IP address, description and ethernet address in addition to the normal interface number.

Constant size Logfiles

MRTG’s logfiles do NOT grow thanks to the use of a unique data consolidation algorithm.

Automatic Configuration

MRTG comes with a set of configuration tools which make configuration and setup very simple.

Performance

Time critical routines are written in C .

GIF free Graphics

Graphics are generated directly in PNG format using the GD library by Thomas Boutell.

Customizability

The look of the webpages produced by MRTG is highly configurable.

RRDtool

MRTG has built-in hooks for using RRDtool. If you are strapped for performance this may help.

Prerequisites

You need to make sure you have apache2,snmp packages are installed before starting MRTG installation

sudo apt-get install apache2 snmpd snmp

Now you need to edit the /etc/snmp/snmpd.conf file

sudo vi /etc/snmp/snmpd.conf

uncomment the following line

#rocommunity public localhost

to

rocommunity public localhost

Save and exit the file

You need to restart the snmpd service using the following command

sudo systemctl snmpd restart

Install MRTG Using the following command

sudo apt-get install mrtg

MRTG Configuration

You need to create mrtg directory under /var/www/html

sudo mkdir /var/www/html/mrtg

Backup the original /etc/mrt.cfg file:

sudo cp /etc/mrtg.cfg /etc/mrtg.cfg.ORIGINAL

Now you need to edit the /etc/mrt.cfg file

vi sudo /etc/mrt.cfg

change the working directory from

WorkDir: /var/www/mrtg

to

WorkDir: /var/www/html/mrtg

Save and exit the file

Create a configuration file for MRTG:

cfgmaker @ > /etc/mrtg.cfg

In this case we are using local server we are trying to monitor and output looks similar to the following

# cfgmaker [email protected] > /etc/mrtg.cfg

--base: Get Device Info on [email protected]:
--base: Vendor Id: Unknown Vendor - 1.3.6.1.4.1.8072.3.2.10
--base: Populating confcache
--base: Get Interface Info
--base: Walking ifIndex
--snpd: [email protected]: -> 1 -> ifIndex = 1
--snpd: [email protected]: -> 2 -> ifIndex = 2
--snpd: [email protected]: -> 3 -> ifIndex = 3
--base: Walking ifType
--snpd: [email protected]: -> 1 -> ifType = 24
--snpd: [email protected]: -> 2 -> ifType = 6
--snpd: [email protected]: -> 3 -> ifType = 6
--base: Walking ifAdminStatus
--snpd: [email protected]: -> 1 -> ifAdminStatus = 1
--snpd: [email protected]: -> 2 -> ifAdminStatus = 1
--snpd: [email protected]: -> 3 -> ifAdminStatus = 1
--base: Walking ifOperStatus
--snpd: [email protected]: -> 1 -> ifOperStatus = 1
--snpd: [email protected]: -> 2 -> ifOperStatus = 1
--snpd: [email protected]: -> 3 -> ifOperStatus = 1
--base: Walking ifMtu
--snpd: [email protected]: -> 1 -> ifMtu = 65536
--snpd: [email protected]: -> 2 -> ifMtu = 1500
--snpd: [email protected]: -> 3 -> ifMtu = 1500
--base: Walking ifSpeed
--snpd: [email protected]: -> 1 -> ifSpeed = 10000000
--snpd: [email protected]: -> 2 -> ifSpeed = 1000000000
--snpd: [email protected]: -> 3 -> ifSpeed = 1000000000

If you see the following error after running the above command you need to make sure you have completed the SNMP change discussed in the starting of this tutorial.

ERROR: did not find any matching data in cfg file

Create and index file for the webserver

indexmaker /etc/mrtg.cfg > /var/www/html/mrtg/index.html

You can access MRTG using the following URL

http:///mrtg

Output looks as follows

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Related posts

(20161025 – The software versions used in this post were updated — iceflatline)

(20150902 – The steps and script in this post were amended to remove logging — iceflatline)

This post will describe how to install and configure Tobi Oetiker’s MRTG (Multi Router Traffic Grapher) on your Ubuntu server. All steps assume that the Apache http server is installed and operating correctly. Once configured, you’ll be able to use MRTG to monitor the traffic in and out of your network using the SNMP capability in your network’s gatewayrouter. MRTG generates static HTML pages containing PNG images which provide a visual representation of this traffic. MRTG typically produces daily, weekly, monthly, and yearly graphs. MRTG is written in perl and works on Unix/Linux as well as Windows. MRTG is free software licensed under the GNU GPL.

Software versions used in this post were as follows:

• Ubuntu Server v16.04.1 x64 LTS)
• mrtg v2.17.4-3ubuntu1

So, let’s get started.

Download and Install

First, update your package list:

Then download and install MRTG:

If this is the first time installing MRTG on your server you’ll likely be presented with the following message (See Figure 1). Answering “Yes” means that the MRTG configuration file will not be readable by others (file permissions set to 640). Answering “No” means that the file is readable by others (file permissions set to 644). In this example we’re going to accept the default Yes.

Figure 1

MRTG installs a sample configuration file /etc/mrtg.cfg used to hold the SNMP information obtained from your gatewayrouter. For a full listing of what MRTG installs and where, run the locate command:

Technically speaking, mrtg.cfg could remain in /etc, but just to keep things tidy let’s create a directory for it and move it into that directory:

That’s it for installing MRTG. Now let’s move on and configure it.

Configure

MRTG includes a script called cfgmaker that will help us populate /etc/mrtg/mrtg.cfg with the information obtained from your gatewayrouter. But before you run cfgmaker, you should setup the SNMP service in your gatewayrouter. This usually involves logging into your gatewayrouter and enabling SNMP. The default SNMP community name is typically “public.” If you change the SNMP community name to something else, make note of it. Now, run the following command, substituting your SNMP community name, if you’ve changed it, and adding the IP address of your gatewayrouter:

If you would like to add more than one gatewayrouter to MRTG simply append the additional URL(s) to the same mrtg.cfg file. Then, when you build the web page using the indexmaker command described below, all the gatewayrouters (and their associated graphs) will be displayed on the same HTML page.

Next, open /etc/mrtg/mrtg.cfg and make sure under Global Configuration Options that the lines “WorkDir: /var/www/mrtg” (under Debian), and “Options[_]: growright, bits” (under Global Defaults) are uncommented. Finally, add the following lines to the existing line EnableIPv6: no under the Global Defaults section:

What does all this do? The line RunAsDaemon: Yes will enable MRTG to…um… run as a daemon. This is beneficial because MRTG is launched only once, thus the parsing of the /etc/mrtg/mrtg.cfg file is done only once, not repeatedly as would be the case if one were to run MRTG as a cron task – another acceptable method for running MRTG. Also, when running as a daemon, MRTG itself is responsible for timing the measurement intervals; therefore, we need to add the Interval line option and assign it a value – in this example 5. This means that every five minutes MRTG will poll the SNMP service in your gatewayrouter and update its graphs. Finally, since many gatewayrouters do not currently support SNMP over IPv6, we’ll retain the line EnableIPv6: no.

Speaking of graphs, by default MRTG graphs grow to the left, so by adding the option “growright” the direction of the traffic visible in MRTG’s graphs flips causing the current time to be at the right edge of the graph and the history values to the left. We’ve also chosen the “bits” option, which means that the monitored traffic values obtained from your gatewayrouter are multiplied by 8 and displayed bits per second instead of bytes per second.

Okay, now it’s time to create the web pages which display the MRTG graphs using the indexmaker command. Run the following commands:

Open /etc/apache2/apache2.conf and add the following lines in the section containing similar Directory directives:

Then restart Apache:

When restarting Apache you may receive a warning concerning its inability to “…reliably determine the server’s fully qualified domain name…” This non-critical error can be fixed by adding the following line to /etc/apache2/apache2.conf:

MRTG has been configured. Let’s start it up and see what it displays.

Start

There’s something important to keep in mind when starting MRTG, and that is that MRTG requires the environmental variable “LANG” to be C in order to run properly. Since most Linux systems these days, including Ubuntu server, use UTF-8 (run echo $LANG to see what your system uses), let’s change LANG to C and start MRTG using the following command:

When you run MRTG for the first time you may see a lot of complaints about missing log files. No worries, this is normal for the first 2-3 times you start MRTG this way. If, however, it continues to complain you may want to look into the source of the problem.

Well, that’s it. Now point your browser to http://your-server-address/mrtg and you should see a page that resembles Figure 2. You may have more or less graphs depending on the number of interfaces reported by your gatewayrouter(s).

Figure 2

Because of the aforementioned option in /etc/mrtg/mrtg.cfg, you’ll see the graph starting “grow” to the right as the traffic is monitored over time, and the Y axis displayed as bits per second. If you click on any one of these graphs you’ll be taken to another page showing individual graphs for 30 minute, two hour, and daily averages, along with the maximum, average, and current bit rate in and out of that particular interface. Only interested in displaying one particular interface? Want to graph other SNMP data? No worries, just remember to run indexmaker again to update the MRTG index.html file.

Okay, so now that we have MRTG installed, configured and running let’s move on and discuss how to keep it running.

Operate

Starting MRTG by hand is not ideal in the long run. So perhaps after you’ve done some tweaking on MRTG and are satisfied with the results, you can automate the process of running MRTG by using a startup script in your system startup sequence. Here’s the script that I use:

To use the script, save it to your home directory as mrtg and make it executable. Then move or copy it to /etc/init.d:

Now, link the mrtg script to all of Ubuntu server’s multi-user run levels (2-5):

Now, let’s start MRTG using our script. If it’s currently running then substitute restart for start in the following command:

That’s it. Now if for some reason your server is rebooted, MRTG should fire up automatically. If you would like to remove the MRTG script from the server’s multi-user run levels, use the command sudo update-rc.d -f mrtg remove).

Conclusion

This concludes the post on how to install and configure MRTG on Ubuntu server. As you can see, MRTG isn’t terribly complicated and proves to be a really nice open source package for monitoring and displaying traffic in and out your network from virtually anywhere you have a web browser. For a full list of all the configuration options and other information I encourage you to visit the MRTG web site.

References

http://oss.oetiker.ch/mrtg/doc/index.en.html