Using MRTG with Linksy Routers

How to setup MRTG to graph statistics from Linksys routers

#####Props to Mathew Atkins who did the orginal write up and collector.pl script. I just edited it to suit my needs.#####
http://www.akins.org/matthew/linksys.html

Requirements

Linksys EtherFast Cable/DSL -- I use BEFSR41 with firmware version 1.42
Red Hat Linux -- Or any *Nix OS
Net SNMP
MRTG

Procedures

Installation

Install NetSNMP.
Install MRTG.
Copy the Perl Scriptcollector.pl to /usr/local/bin/collector.pl and chmod 755

Configuration

Enable SNMP Logging in the router by navigating to the Log Section and placing
the IP address of your Linux server as the logging destitation.
Edit /etc/snmp/snmptrapd.conf and place the following entry: NOTE: You may need to create this file
```
traphandle default /usr/local/bin/collector.pl
```

Edit your mrtg.cfg with the following entry to monitor Traffic on the Router

#################################
#       GLOBAL                  #
#################################

WorkDir: /var/www/html/mrtg

#################################
#  Linksys Roouter              #
#################################
WriteExpires: Yes
Title[^]: Traffic Analysis for
Title[router]: Linksys Router
PageTop[router]:Linksys Firewall/Router
Target[router]: `cat /tmp/router.out`
MaxBytes[router]: 187000

Configuration Test

To ensure that your server is recieving the traps, run
```
snmptrapd -d -O T
```
Now, from a machine behind the router, surf the web
for a bit to generate some packet logs.
cat /var/log/syslog and you should see lots of info regarding web traffic
being logged from the router.
cat /tmp/router.out
And you should see the following output that should cahnge whenever a trap is received.
```
1352664
539539171
0:5:17:56.71
router
```
Run mrtg against your mrtg.cfg file
```
/usr/local/mrtg-2/bin/mrtg /var/www/html/mrtg/mrtg.cfg
```
You should see various file appearing in the working directory of your mrtg configuration file.
You will get errors the first couple of times running mrtg but this is normal.
If you are still getting errors after the fourth time, something is wrong and you should
double check your configuration.

Finishing touches

Start the snptrapd daemon and set it so it starts on boot.

I use the following bash script in /etc/init.d and is called by rc*.d files


#!/bin/bash
/usr/sbin/snmptrapd -d -O T

Add mrtg to roots crontab so that it runs every five.
Notice how mrtg logs to the mrtg.log file

#Added for MRTG
0,5,10,15,20,25,30,35,40,45,50,55 * * * *  /usr/local/mrtg-2/bin/mrtg 

/var/www/html/mrtg/mrtg.cfg --logging /var/log/mrtg.log #1>/dev/null 2>/dev/null

Now you should be able to browse to your server and see the MRTG graphs.
With a little web surfing, you should see some results in 10 to 15 minutes.

MRTG Graphs for Linksys Cable/DSL Router