1. Introduction
MRTG (Multi Router Traffic Grapher) is an application that allows us to observe the traffic of a network. It generates html pages with graphs which are refreshed according to our network’s current state. Its source is written in Perl and C which means that it can be installed in every Operating System we like. We will also need SNMP daemon (Simple Network Management Protocol) which gives us information for a network. The following installation was accomplished under Linux and specifically Fedora Core 6. With some little changes it can be used and under other distros.
2. SNMP server
2.1 Installation
Initially we install the packets needed for SNMP. Yum makes this job a lot easier.
Next we make snmpd service to start automatically for the runlevels we want.
| # yum install net-snmp-utils net-snmp |
And we start the server.
| # chkconfig --level 345 snmpd |
We can see that it is running in port 199.
# netstat -natv | grep ':199'
tcp 0 0 127.0.0.1:199 0.0.0.0:* LISTEN |
2.2 Configuration
We run ‘snmpwalk’ which creates a “tree” of information for our network.
If you see an output like this one you may proceed with the MRTG installation. Else you should make some configuration first.
| # snmpwalk -v 1 -c public localhost IP-MIB::ipAdEntIfIndex |
ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.127.0.0.1 = 1
ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.192.168.0.3 = 2 |
We keep a backup of snmpd.conf just in case anything goes wrong
| # cp /etc/snmp/snmpd.conf /etc/snmp/snmpd.conf.original |
We open it
| # nano /etc/snmp/snmpd.conf |
And do the follow changes:
| com2sec notConfigUser default public |
with those
com2sec local localhost public
com2sec mynetwork 10.0.0.0/8 public |
where 10.0.0.0/8 we put what our network is
| group notConfigGroup v1 notConfigUser group notConfigGroup v2c notConfigUser |
with those
group MyRWGroup v1 local
group MyRWGroup v2c local
group MyRWGroup usm local
group MyROGroup v1 mynetwork
group MyROGroup v2c mynetwork
group MyROGroup usm mynetwork |
| view systemview included .1.3.6.1.2.1.1 view systemview included .1.3.6.1.2.1.25.1.1 |
with this one
| access notConfigGroup "" any noauth exact systemview none none |
with those
access MyROGroup "" any noauth exact all none none
access MyRWGroup "" any noauth exact all all none |
- and finally we change those lines
| syslocation Unknown (edit /etc/snmp/snmpd.conf) syscontact Root (configure /etc/snmp/snmp.local.conf) |
with something like this
2.3 Check
We restart the server to take affect of the notices
And we run again
| # snmpwalk -v 1 -c public localhost IP-MIB::ipAdEntIfIndex |
Now we should see something like that
IP-MIB::ipAdEntIfIndex.10.103.0.33 = INTEGER: 2
IP-MIB::ipAdEntIfIndex.127.0.0.1 = INTEGER: 1 |
Where 10.103.0.33 is your ip address.
3. MRTG
3.1 Installation
We again use yum
3.2 Configuration
We create the folder in which our graphs and html pages will be kept
| # mkdir /var/www/html/mrtg/ |
And we run ‘cfgmaker’ for the configuration file to be created.
| # cfgmaker --global "workdir: /var/www/mrtg" -ifref=ip --output /etc/mrtg/mrtg.cfg --global 'options[_]: growright,bits' public@localhost |
Here you should pay notice to
--output /etc/mrtg/mrtg.cfg as long as to
public@localhost. With this command we tell MRTG to create a configuration file with the name ‘mrtg.cfg’ for the traffic of our computer (localhost). Instead of localhost you may put the address of any computer you may monitor as long as it runs SNMP.
Next we create our default index page
| # indexmaker --output=/var/www/html/mrtg/index.html /etc/mrtg/mrtg.cfg |
3.2.1 Apache configuration
Next we have to configure apache for MRTG to work correctly. MRTG creates a file ‘mrtg.cfg’ under /etc/httpd/conf.d we contains all the necessary for Apache. We change it to contain the ips we want to have access to our MRTG graphs. Here I have added all my network.
Alias /mrtg /var/www/mrtg
Order deny,allow
Deny from all
Allow from 127.0.0.1 10.0.0.0/8
|
3.3 Check
We run the following command
In case you get an error like this
| # mrtg /etc/mrtg/mrtg.cfg |
ERROR: Mrtg will most likely not work properly when the environment
variable LANG is set to UTF-8. Please run mrtg in an environment
where this is not the case. Try the following command to start:
env LANG=C /usr/bin/mrtg /etc/mrtg/mrtg.cfg |
you have to run the above command more than once till it runs without any error. This is normal.
# env LANG=C /usr/bin/mrtg /etc/mrtg/mrtg.cfg 23-02-2007 17:28:53, Rateup WARNING: /usr/bin/rateup Can't remove localhost_2.old updating log file
# env LANG=C /usr/bin/mrtg /etc/mrtg/mrtg.cfg
# |
Finally we open our browser and type
You should see something like this
And by clicking on it something like this
There are daily, weekly, monthly and yearly graphs which aren’t shown in the screenshot. By changing the .cfg file we can alter the information displayed to what we just want.
4. Outroduction
With the same way it is possible to add as many computers as we want and therefore have a general overview of our network. Enjoy! ;)
