Here's what I did to set up MRTG on a debian box:

• Installed snmpd (MRTG uses snmpd for network monitoring.

• Changed the snmpd config file to uncomment the "readonly" entry and comment out the "paranoid" entry. The new configuration looks like this:

      #       sec.name  source          community
      #com2sec paranoid  default         public
      com2sec readonly  default         public
      #com2sec readwrite default         private
  

  Restarted snmpd after this:

      # /etc/init.d/snmpd restart
  

• Changed my webserver config files so that /var/www/mrtg is aliased to an appropriate subdirectory (you don't need to do this if /var/www is already your DocumentRoot, this is the debian default).

• Added the following info to my /etc/mrtg.cfg file:

      RunAsDaemon: no
      EnableIPv6: no
      Options[_]: bits,growright
  

  I prefer to follow Debian's convention of running mrtg every five minutes from a cron job as opposed to running it as a daemon. If you'd rather run mrtg as a daemon, just set RunAsDaemon to "yes" - the cron job will then just become a keepalive job.

• Ran " cfgmaker public@127.0.0.1 >> /etc/mrtg.cfg" to create the monitoring for the network interfaces on localhost.

• Ran " indexmaker /etc/mrtg.cfg > /var/www/mrtg/index.html" to regenerate the index page (you need to do this when making configuration changes that add stuff to mrtg).

And now I have some spiffy bandwidth graphs. Thanks MRTG guys!