Install and Configure MRTG

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. You need the following packages:

• mrtg : Multi Router Traffic Grapher
• net-snmp and net-snmp-utils : SNMP (Simple Network Management Protocol) is a protocol used for network management. The NET-SNMP project includes various SNMP tools. net-snmp package contains the snmpd and snmptrapd daemons, documentation, etc. You also want to install the net-snmp-utils package, which contains NET-SNMP utilities.

Step # 1: Install MRTG

Type the following command to install packages using yum command under Redhat Linux:

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

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,

# vi /etc/snmp/snmpd.conf

Update it as follows to only allow access from localhost:

com2sec local     localhost           public

group MyRWGroup v1         local

group MyRWGroup v2c        local

group MyRWGroup usm        local

view all    included  .1                               80

access MyRWGroup ""      any       noauth    exact  all    all    none

syslocation VSNL, India

syscontact Root <vivek@nixcraft.tld>

(Comment older configuration in snmpd.conf)

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.123.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/html/mrtg' --output /etc/mrtg/mrtg.cfg public@localhost

--global 'WorkDir: /var/www/mrtg' : add global config entries i.e. set workdir to store MRTG graphs.

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

public@localhost : public is the community name of the device you want to create a configuration for. If you are using the wrong community name you will get no response from the device. localhost is the DNS name or the IP number of an SNMP-managable 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/html/mrtg/index.html /etc/mrtg/mrtg.cfg

Step # 4: Verify Cron Job

/etc/cron.d/mrtg runs mrtg command to monitor the traffic load on network links:

# cat /etc/cron.d/mrtg

Sample Output:

*/5 * * * * root 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

Just make sure crond is running and you are done with configuration:

# chkconfig --list crond
If it is off in run level # 3, just run the following to turn on crond service:

# chkconfig crond on

# service crond on

Step # 5:- Testing

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

# yum install httpd

# chkconfig httpd on

# service httpd on

 webbrowser and type the url:

http://your-ip.add.ress/mrtg/

http://192.168.1.5/mrtg/