MRTG on Linux

MRTG on Linux

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Introduction

MRTG is wonderful tool. You can use it to monitor traffic on your router or leased server located at remote IDC. Since it is written in Perl and some code in C language, it is portable and high performance tool.

What is MRTG?

As explained in official mrtg(1) man page “The Multi Router Traffic Grapher (MRTG) is a tool to monitor the traffic load on network-links. MRTG generates HTML pages containing GIF images which provide a LIVE visual representation of this traffic. Please note following discussion based upon Red Hat Linux Enterprise version 4.

What is SNMP and why should I care?

SNMP is Simple Network Management Protocol. It is use to manage IP network devices such as servers, routers, switches etc. Administrator can find or manage network performance, solve problem or even optimize it further. For more information on official UNIX/Linux SNMP please see UCD-SNMP/NET-SNMP Tutorials and an excellent resource at Snmplink.org

Assumptions

These installation instructions assume you have:

  • Linux distribution
  • You would like to perform MRTG and snmp binary installation using rpm. If you are looking for source installation then visit author’s web site here. This page has an excellent information (systematically) to install it from source.
  • Required RPMs
    • mrtg
    • snmp
    • snmp-utils
  • Installations were tested on Red Hat Enterprise Linux version 4 & 5.

Configuration

Make sure snmp server is working. Without proper working snmp server, mrtg will not work. Therefore, first step is make sure snmp up and running. Following steps will take you gradually to configure it.

Configure SNMP

(1) Edit file /etc/snmp/snmpd.conf using text editor:

# vi /etc/snmp/snmpd.conf

Change/Modify line(s) as follows:

Find following Line:

com2sec notConfigUser  default       public

Replace with (make sure you replace 192.168.0.0/24 replace with your network IPs) following lines:

com2sec local     localhost           public
com2sec mynetwork 192.168.0.0/24      public

Scroll down bit and change:

Find Lines:

group   notConfigGroup v1           notConfigUser
group   notConfigGroup v2c           notConfigUser

Replace with:

group MyRWGroup v1         local
group MyRWGroup v2c        local
group MyRWGroup usm        local
group MyROGroup v1         mynetwork
group MyROGroup v2c        mynetwork
group MyROGroup usm        mynetwork

Again scroll down bit and locate following line:

Find line:

view    systemview     included      system

Replace with:

view all    included  .1                               80

Again scroll down bit and change:

Find line:

access  notConfigGroup ""      any       noauth    exact  systemview none none

Replace with:

access MyROGroup ""      any       noauth    exact  all    none   none

access MyRWGroup ""      any       noauth    exact  all    all    none

Scroll down bit and change:

Find lines:

syslocation Unknown (edit /etc/snmp/snmpd.conf)
syscontact Root  (configure /etc/snmp/snmp.local.conf)

Replace with (make sure you supply appropriate values):

syslocation Linux (RH4_UP4), Ravi’s Linux Router.

syscontact Ravi Bhure <ravi@indianGNU.org>

Start your snmp server and test it:

(a) Make sure when linux comes up snmpd always starts:

 # chkconfig snmpd on

(b) Make sure service start whenever Linux comes up (after reboot):

 # service snmpd start

(c) Finally test your snmp server:

# snmpwalk -v 1 -c public localhost IP-MIB::ipAdEntIfIndex

Install mrtg if not installed

Mrtg software may install during initial installation; you can verify if MRTG installed or not with following RPM command:

rpm -qa | grep mrtg

Use rpmfind.net to find MRTG rpm or up2date command to install MRTG software:

# up2date -v -i mrtg

Fedora Linux user can use yum command as follows to install MRTG:

# yum install mrtg

Commands to Configure mrtg

(a) Create document root to store mrtg graphs/html pages:

# mkdir -p /var/www/html/mymrtg/

(b) Run any one of the following cfgmaker command to create mrtg configuration file:

#cfgmaker --global 'WorkDir: /var/www/html/mymrtg' --output /etc/mrtg/mymrtg.cfg public@localhost

OR (make sure your FQDN resolves, in following example i’m using example.com which is my router FQDN address)

# cfgmaker --global 'WorkDir: /var/www/html/mymrtg' --output /etc/mrtg/mymrtg1.cfg public@example.com

(c) Create default index page for your MRTG configuration:

# indexmaker --output=/var/www/html/mymrtg/index.html /etc/mrtg/mymrtg1.cfg

(d) Copy all tiny png files to your mrtg path:

# cp -av /var/www/mrtg/*.png /var/www/html/mymrtg/

(e) Create /etc/httpd/conf.d/mymrtg.conf and write just one line

Alias /mymrtg /var/www/mymrtg

Save and exit.

First test run of mrtg

(a) Run mrtg command from command line with your configuration file:

# mrtg /etc/mrtg/mymrtg1.cfg

Note: You may get few warning message for first time; ignore them.

(b) Fire your favorite web browser (like FireFox 😀 ) and type url http://www.your.com/mymrtg/ or http://your-ip/mymrtg/

Create crontab entry so that mrtg graph / images get generated every 5 minutes

(a) Login as a root user or login as a mrtg user and type following command:

# crontab -e

(b) Add mrtg cron job entry to configuration file (append following line to it):

*/5 * * * * /usr/bin/mrtg /etc/mrtg/mymrtg1.cfg --logging /var/log/mrtg.log

Save file and you are done with MRTG config issues 🙂

NOw NJoy MRTG.

Thanks

Ravi

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