Multi Router Traffic Grapher – MRTG on Linux

The Multi Router Traffic Grapher (MRTG) is a network or resource monitoring tool used by System Administrators across the Globe. MRTG generates HTML pages containing PNG images, which provides a real time visual representation of network traffic and system resources.

STEP 1: Install MRTG with required packages

# yum install mrtg net-snmp net-snmp-utils -y

STEP 2: Configure snmpd

If you need to monitor localhost including interface and other stuff such as CPU, memory etc, configure snmpd. Open /etc/snmp/snmpd.conf,

# vim /etc/snmp/snmpd.conf

Do changes in it as follows to only allow access from localhost:

com2sec   local      localhost       public

group      rwroup     v1         local

group     rwgroup    v2c         local

group      rwgroup    usm        local

view      all        included       .1   80

access   rwgroup    “”  any   noauth    exact  all    all    none

syslocation BSNL, India

syscontact Root

Save and close the file. Restart snmpd:

# chkconfig snmpd on; service snmpd restart

Make sure you see interface IP, by running the following command:

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

Sample Outputs:

IP-MIB::ipAdEntIfIndex.121.xx.yy.zzz = INTEGER: 2

IP-MIB::ipAdEntIfIndex.127.0.0.1 = INTEGER: 1

STEP 3: Configure MRTG,

Use cfgmaker command to creates /etc/mrtg/mrtg.cfg file, enter:

# cfgmaker –global ‘WorkDir: /var/www/mrtg’ –output  /etc/mrtg/mrtg.cfg public@localhost

Options Description:

- -global ‘WorkDir: /var/www/mrtg’ : A place – workdir to store MRTG graphs.

- -output /etc/mrtg/mrtg.cfg: configure output filename

public@localhost : public is the community name of the device you want to create a configuration for. localhost is the DNS name or the IP number of an SNMP-manageable device i.e. our local server.

Finally, run indexmaker to create web pages which display the status of an array of mrtg interface status pages:

# indexmaker –output=/var/www/mrtg/index.html /etc/mrtg/mrtg.cfg

STEP 4: Verify Cron Job

# cat /etc/cron.d/mrtg

*/5 * * * * LANG=C LC_ALL=C /usr/bin/mrtg /etc/mrtg/mrtg.cfg –lock-file /var/lock/mrtg/mrtg_l –confcache-file /var/lib/mrtg/mrtg.ok

Now, restart crond service to make it live instantly.

# chkconfig crond on; service crond restart

STEP 5: To view graph,

You need Apache web server to view graphs, simply type the following to install httpd:

# yum install httpd

# chkconfig httpd on ; service httpd start

Now, open http://bubu-online.blogspot.com/mrtg/ . Use your server name instead of bubu-online.blogspot.com.