I would suggest giving MJL85 a try.
Graphviz dot tool
It is a set of python scripts that can analyse and diagram networks with the Graphviz dot tool producing the graphical output.
From the authors site:
The tool is:
Free, Gratis & Open Source
Should run on multiple platforms.
You can install OpenLDAP or ApacheDS on your linux server, if it has not been already installed. Follow the links to get information on how to setup etc. This should not be too difficult. But will offer you the best flexibility in your testing.
Take a look at Untangle. It should do most of what you need.
Note that there is both a paid and a free version of the content filter, and the free version sucks pretty hard. It works, but it's lists aren't very complete. Content filtering is a service that needs a lot of power behind it in order to keep up with the ever-growing internet, and so you won't ...