MRTG Installation and Configuration RHEL7 Step by Step Guide

MRTG – Multi Router Traffic Grapher Open Source tool to monitor any device interface bandwidth with easy steps. In this post i am going to show you. How to Install and configure MRTG installation in Red Hat Enterprise Linux 7 Version step by Step Guide.

Basically this tool is used to monitor interface bandwidth on devices, its simply generates PNG images with HTML support which are LIVE visualization of interface usage. Most useful when you do not have any monitoring tool in hand this open source can help you.

MRTG Installation Prerequisites

• Apache web server installation
• SNMP installation and configuration in Server and client
• MRTG package installation and configuration

Get remote server/device interface traffic details by querying SNMP MIB data. In-Order to get remote device details you have to enable SNMP service in server and configure community string in client machine.

Environment

• Server IP: 192.168.2.5
• Client (Router IP): 192.168.2.10
• SNMP Community String: ArkIT

Install required packages using yum utility command is below

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

Configure SNMP

This SNMP Configuration will be carried out in Linux server and client device as well. 

Login to router Configure SNMP
>enable
Password:

Router# config t

Router(config)#
Router(config)# snmp-server community ArkIT RO

Router(config)#exit

Router#write memory 
Building configuration... 
[OK]

Linux Server SNMP configuration

# cp /etc/snmp/snmpd.conf /etc/snmp/snmpd.conf.bak
# rm -rf /etc/snmp/snmpd.conf
# vi /etc/snmp/snmpd.conf

###### Copy and Paste below config lines #####
rocommunity ArkIT localhost
rocommunity ArkIT 192.168.2.5

# Allow Systems Management Data Engine SNMP to connect to snmpd using SMUX
smuxpeer .1.3.6.1.4.1.674.10892.1
##### Done ####

Start and enable SNMP service

# systemctl start snmpd.service
# systemctl enable snmpd.service

Verify SNMP is working or not using snmpwalk command

# snmpwalk -v2c -c ArkIT 192.168.2.10 system

cfgmaker Configuration Generator

Generate mrtg configuration file using cfgmaker command, if you want monitor multiple devices generate multiple configuration files one file for one device

# cfgmaker --snmp-options=:::::2 --ifref=descr ifdesc=descr ArkIT@192.168.2.10 > /etc/mrtg/router.cfg

By using above command will scan remote router device and its available interfaces, generates the configuration file to /etc/mrtg/router.cfg. Now edit the config file and UN-comment Workdir and change the path (if you want to change to another path) and also UN-comment Options if you want graph data in bits instead of bytes

Workdir: /var/www/html/mrtgOptions[_]: growright, bits

Now check config file is working as expected, below command will run in loop and generate all the html files and PNG files in Work directory location

# for ((i=1; i <= 3; i++ )); do env LANG=C mrtg /etc/mrtg/router.cfg; done

Creates index files for mrtg web sites use indexmaker command

# indexmaker --columns=1 /etc/mrtg/router.cfg > /var/www/html/index.html/index.html

Allow/Deny Web Page

# vi /etc/http/conf.d/mrtg.conf

Alias /mrtg /var/www/html/mrtg

<Location /mrtg>
Order deny,allow
Deny from all
Allow from 127.0.0.1
Allow from 192.168.2.0/24
</Location>

As per the above rule you can only access web page from 192.168.2.x IP addresses, if you want to allow all other networks to access web page specify ‘ALL’ instead of IP address/Net-mask value

Add Firewall Rule

# firewall-cmd --permanent --add-service=snmp#firewall-cmd --permanent --add-service=http# firewall-cmd --reload

Change permissions to allow web browsing

# chown -R apache:  /var/www/html/
# systemctl restart httpd

Schedule data collection using crontab

# crontab -e
*/5 * * * * env LANG=C LC_ALL=C /usr/bin/mrtg /etc/mrtg/router.cfg --lock-file /var/lock/mrtg/mrtg_a --confcache-file /var/lib/mrtg/mrtg.ok

That’s it about configuring mrtg in RHEL7 / Centos7.

Conclusion:

If you would like to configure multiple routers/Devices to monitor via this tool generate multiple configuration files using device names as config file names

Configuration file

cat /etc/mrtg/router.cfg

# Created by
# /bin/cfgmaker --snmp-options=:::::2 --ifref=descr ifdesc=descr ArkIT@192.168.2.5


### Global Config Options

# for UNIX
WorkDir: /var/www/html/

# or for NT
# WorkDir: c:\mrtgdata

### Global Defaults

# to get bits instead of bytes and graphs growing to the right
Options[_]: growright, bits

EnableIPv6: no

######################################################################
# System: rhel7
# Description: Linux rhel7 3.10.0-693.21.1.el7.x86_64 #1 SMP Wed Mar 7 19:03:37 UTC 2018 x86_64
# Contact: root@localhost
# Location: Unknown
######################################################################


### Interface 2 >> Descr: 'ens192' | Name: 'ens192' | Ip: '192.168.2.5' | Eth: '00-50-56-82-d9-83' ###

Target[192.168.2.5_ens192]: \ens192:ArkIT@192.168.2.5:::::2
SetEnv[192.168.2.5_ens192]: MRTG_INT_IP="192.168.2.5" MRTG_INT_DESCR="ens192"
MaxBytes[192.168.2.5_ens192]: 1250000000
Title[192.168.2.5_ens192]: Traffic Analysis for ens192 -- rhel7
PageTop[192.168.2.5_ens192]: <h1>Traffic Analysis for ens192 -- rhel7</h1>
<div id="sysdetails">
<table>
<tr>
<td>System:</td>
<td>rhel7 in Unknown</td>
</tr>
<tr>
<td>Maintainer:</td>
<td>root@localhost</td>
</tr>
<tr>
<td>Description:</td>
<td>ens192 </td>
</tr>
<tr>
<td>ifType:</td>
<td>ethernetCsmacd (6)</td>
</tr>
<tr>
<td>ifName:</td>
<td>ens192</td>
</tr>
<tr>
<td>Max Speed:</td>
<td>1250.0 MBytes/s</td>
</tr>
<tr>
<td>Ip:</td>
<td>192.168.2.5 (rhel7)</td>
</tr>
</table>
</div>

Video Tutorial