MRTG (Multi Router Traffic Grapher) on Redhat Linux 8.10

Step 1: Enable Repositories and Install Dependencies 

# Enable the EPEL repository
[root@node1 ~]#  dnf install -y https://fedoraproject.org

# Enable the CodeReady Builder repository (needed for EPEL dependencies)
[root@node1 ~]#  subscription-manager repos --enable codeready-builder-for-rhel-8-x86_64-rpms

# Update the dnf cache
[root@node1 ~]#  dnf makecache

# Install MRTG, SNMP tools, and Apache Web Server
[root@node1 ~]#  dnf install -y mrtg net-snmp net-snmp-utils httpd

Step 2: Configure and Start SNMP

#Open the SNMP configuration file

[root@node1 ~]# vi /etc/snmp/snmpd.conf

#Map a community name (e.g., public) to a security name. Find or add the line

[root@node1 ~]# rocommunity public 127.0.0.1

#Start and enable the SNMP daemon:

[root@node1 ~]# systemctl enable --now snmpd

Test that SNMP is responding locally:

[root@node1 ~]# snmpwalk -v 2c -c public 127.0.0.1 system

Step 3: Configure Apache Web Server 

Create a web directory to host the HTML and PNG image files that MRTG generates.

# Create the directory for MRTG web files
[root@node1 ~]# mkdir -p /var/www/html/mrtg

# Give ownership to the Apache user
[root@node1 ~]# chown -R apache:apache /var/www/html/mrtg

# Start and enable Apache
[root@node1 ~]# systemctl enable --now httpd

Step 4: Generate the MRTG Configuration File

# Generate the config file
[root@node1 ~]# cfgmaker --global "WorkDir: /var/www/html/mrtg" \
             --global "Options[_]: growright,bits" \
             --output=/etc/mrtg/mrtg.cfg \
             public@127.0.0.1

Step 5: Generate the Web Index Page

Use indexmaker to scan your newly created mrtg.cfg and generate a central web index page:

[root@node1 ~]# indexmaker --output=/var/www/html/mrtg/index.html /etc/mrtg/mrtg.cfg

Step 6: Test Run MRTG

(Note: It is normal to see warnings about missing log files during the first two runs, as it has to build them from scratch.)

[root@node1 ~]#env LANG=C mrtg /etc/mrtg/mrtg.cfg

Run the command a second and third time until the error messages disappear.

Step 7: Automate Data Collection via Cron

MRTG needs to sample network metrics consistently (usually every 5 minutes). Create a cron job to handle this automatically: 

#Open the root crontab 

[root@node1 ~]# sudo crontab -e

#Add the following entry to execute MRTG every 5 minutes

*/5 * * * * env LANG=C /usr/bin/mrtg /etc/mrtg/mrtg.cfg >/dev/null 2>&1

Step 8: Adjust Firewall and SELinux (If applicable)

Allow external traffic through your firewall so you can access the web page:

# Allow HTTP traffic
[root@node1 ~]#firewall-cmd --permanent --add-service=http
[root@node1 ~]#s firewall-cmd --reload

now view your traffic charts by navigating a browser to http://<your-server-ip>/mrtg/

http://192.168.184.131/mrtg/