I noticed that the iostat plugin was broken and was not returning any values. To fix this you need to change a line in the plugin code.

nano -w /usr/share/munin/plugins/iostat

You need to change line 176 to read:

next unless $tmpnam !~ \/c\d+d\d+$/

In nano, press ctrl + shift + – (or ctrl+underscore) and type 177 [enter]

That should do it!

Its a perl script which requires IPTables to be installed, and before running, a small config file needs to be created at /etc/anonymiser.conf containing something like this:

@mynets = ("192.168.0.0/24","192.168.1.0/24","10.0.0.0/8");
$TOR_UID = `id -u debian-tor`;
1;

The script basically checks to see if Tor is installed, if not, install it, configure it so DNS is routed too (enhances security), and writes a bunch of IPTables rules to route outgoing streams through the (newly) installed Tor service.

To download or fork the script, you can grab it from here:

https://github.com/andydixon/TransparentLinuxAnonymity

Edit: Actually, looking at it, its written for Debian based Linux distributions..