I'm using the current standard Raspbian Linux image, which you can download here and find instructions for installing here. These instructions are quite good and will get you up and running quickly.

Applications on Linux systems are installed as "packages". When you install the standard Raspbian image, it includes a lot of cool packages related to education and learning coding. While this is a great teaching tool, we don't need a lot of this and it's just taking up space. If you have a big Micro SD card, space isn't a big deal. But if you have a small one, or just don't like clutter, it can be.

Login to your Pi and run the following command in a terminal window:

$ sudo apt purge bluej geany geany-common greenfoot idle idle-python2.7 idle-python3.4 idle3 \
   minecraft-pi nodejs nodejs-legacy nodered nuscratch penguinspuzzle python-minecraftpi \
   python-picraft python-pygame python-sense-hat python3-gi python3-minecraftpi python3-picraft \
   python3-pgzero python3-pygame python3-sense-hat sense-emu-tools sense-hat sonic-pi \
   squeak-plugins-scratch squeak-vm supercollider supercollider-common supercollider-ide \
   supercollider-language supercollider-server supercollider-supernova wolfram-engine

For the uninitated, the $ here is the shell prompt, like C:\> in DOS. You don't have to type that, just copy/paste everything after that. Answer Y when prompted to confirm removal of the packages. You may also use the command remove instead of purge here if you like. I prefer purge because it also deletes configuration files for a cleaner sweep of your system.

Once this is done (it will take a few minutes) you may reboot if you like to cleanup stray icons, but it isn't necessary.

Now that we have a clean system, unencumbered by extraneous applications, it's time to install the stuff we need to run our tests. Run the following command in a terminal window to do so.

$ sudo apt install cdpr dia ethtool iperf lighttpd lldpd php5 php5-cgi php5-common speedtest-cli \
   tightvncserver wireshark zenmap

Answer Y when prompted to confirm installation of the packages. For reference, here's what each of these packages are for:

• cdpr: Cisco Discovery Protocol Reporter: queries Cisco devices for port information
• dia: Editor for diagrams, graphs, charts etc (may not be practical on small TFT displays)
• ethtool: used to identify such things as link speed and duplex for your connection
• iperf: measuring TCP and UDP bandwidth performance
• lighttpd: lightweight web server (alternative to apache or nginx, which you may use if you prefer)
• lldpd: tool to query link-layer discovery protocol (LLDP) packets, the industry-standard way to identify port information
• php5, php5-cgi, php5-common: the web UI is written using PHP; you need these for it to work
• speedtest-cli: command line interface to check with Speedtest.net to measure your bandwidth to the Internet
• tightvncserver: lightweight VNC server, useful for remotely testing the setup on your Pi
• wireshark: GUI network packet analyzer (may not be practical on small TFT displays)
• nmap: TCP/UDP port sniffer
• zenmap: GUI for nmap (may not be practical on small TFT displays)

For more detailed information on any of these, run the following in a terminal window:

$ apt show <PACKAGE>

where <PACKAGE> is the name of the one you are interested in.