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Recently, a Maplins kit of all sorts of LED segment displays and a LCD screen came into my possession, a fairly interesting array of components are in this bag, so I started to play around with them as there was no instruction manual.

Here’s the kit if anyone’s interested in picking one up:

Counting Devices on the Local Network and Displaying Them on Our Display:

So, with little knowledge of the GPIO ports or their correlation with raspbian’s gpio command line utility, I rigged up the 7-segment display to my Pi with the use of a breadboard and a gpio breakout cable, here’s a similar kit available from Adafruit: https://www.adafruit.com/products/914

Here’s my notes from plugging in the 7 segment display:

And here’s the final product:

(ignore the random transistor)

You can power either the 3rd pin or the 8th pin, depending on aesthetics, as you can see I chose the 8th pin. Remember to use a ±330ohm transistor between the 3.3v power pin and the 8/3 pin on the 7 segment display or you’ll blow it!

Now for the software side:

You’ll want to install the python Raspberry Pi GPIO command line utility via the following method:

apt-get update && apt-get install python-rpi.gpio arp-scan

Once this is finished, you can run the below (very simple, I just threw it together) bash script (use sudo!) which will show the number of devices on your network on your 7 segment display!

for i in 6 7 8 9 10 11 12 13; do gpio write $i 1; done
 while true; do
 case $arp in
 1 )
 if [ "$arp" = "1" ]
 then
 for i in 7 9; do gpio write $i 0; done
 else
 echo ""
 fi ;;
 2 )
 if [ "$arp" = "2" ]
 then
 for i in 8 9 10 11 12; do gpio write $i 0; done
 else
 echo ""
 fi ;;
 3 )
 if [ "$arp" = "3" ]
 then
 for i in 7 8 9 11 12; do gpio write $i 0; done
 else
 echo ""
 fi ;;
 4 )
 if [ "$arp" = "4" ]
 then
 for i in 7 9 12 13; do gpio write $i 0; done
 else
 echo ""
 fi ;;
 5 )
 if [ "$arp" = "5" ]
 then
 for i in 7 8 11 12 13; do gpio write $i 0; done
 else
 echo ""
 fi ;;
 6 )
 if [ "$arp" = "6" ]
 then
 for i in 7 10 11 12 13; do gpio write $i 0; done
 else
 echo ""
 fi ;;
 7 )
 if [ "$arp" = "7" ]
 then
 for i in 7 8 9; do gpio write $i 0; done
 else
 echo ""
 fi ;;
 8 )
 if [ "$arp" = "8" ]
 then
 for i in 7 8 9 10 11 12 13; do gpio write $i 0; done
 else
 echo ""
 fi ;;
 9 )
 if [ "$arp" = "9" ]
 then
 for i in 7 8 9 12 13; do gpio write $i 0; done
 else
 echo ""
 fi ;;
 10 )
 if [ "$arp" > "9" ]
 then
 for i in 12; do gpio write $i 0; sleep 0.5; gpio write $i 1; done
 else
 echo ""
 fi ;;
 esac
 arp=$(expr `arp-scan -l | wc -l` - 5 &)
 sleep 30
 for i in 6; do
 gpio write $i 1
 sleep 0.5
 gpio write $i 0
 sleep 0.5
 gpio write $i 1
 sleep 0.5
 gpio write $i 0
 sleep 0.5
 gpio write $i 1
 sleep 0.5
 gpio write $i 0
 for i in 6 7 8 9 10 11 12 13; do gpio write $i 1; done
 done
 done

You may have heard about DNS tunnelling before, it’s the process of encoding data and sending it to our chosen name server. The NS realises it cannot resolve the query and subsequently forwards it onto the tcp-over-dns server. The tcp-over-dns server then decodes the data we sent encodes the server’s data in the answer and replies to us, the client.

So how does this help me? Well, think of Hotels, Airports and recently Airplanes! They all charge users for internet usage, we can bypass this with the use of DNS requests to external hosts which most systems do not yet block (it’s as simple as implementing split horizon DNS yet hardly anyone has). DNS tunnels are rather slow, but allow you to reply to emails and browse simple pages whilst travelling, expect around 20KB/s.

Using Iodine:

Tools you’ll need:

• Linux server
• OSX Client computer
• A domain

On The Server:

• Install iodine with either aptitude [apt-get install iodine] or from source: http://dev.kryo.se/iodine/
• Start the iodine daemon with:

  iodined -f -c -P [yourpassword] 10.0.0.1 [yourdomain]

Client Setup:

• I used Mac OSX with homebrew installed which had the package already:

  brew install iodine

• Linux users can simply

  apt-get install iodine

• You also need to install TUN/TAP drivers for OSX: http://tuntaposx.sourceforge.net/

DNS Setup:

• With your registrar, you will want to set up something similar to this:

tunnelhost     IN      A       10.15.213.99
tunnel         IN      NS      tunnelhost.mytunnel.com

Final Stage:

• Now to connect, use: 

  sudo iodine -f -P [yourpassword] 10.15.213.99 tunnel.mytunnel.com

• If you have issues, try adding -T to the client parameters
• You can now ssh -D xxxx [email protected] and use a socks proxy to route traffic through your DNS tunnel! Enjoy!

So, as per my previous post, OVH BHS Servers are being handed out to beta testers free to use until mid August 2012. I’ve been testing my allocated dev server for three days.

Now, let’s just go over those specs again:

• 16 gb RAM – 2x8GB 1333 MHz Non ECC DDR2 Kingston modules.

• 1tb hdd — On further inspection, 2x 1Tb HDDs in RAID 1, good for drive redundancy!

• 100mbps connection — IPerf test from OVH France (Kimsufi box) resulted in 87.1Mbps, feel free to trace-route 198.245.62.123
• Quad Core Intel(R) Core(TM) i3-2130 CPU @ 3.40GHz
• Running Debian Squeeze by default (6.0)
• 1 IPv4 Address
• /64 subnet of IPv6 addresses (standard with every OVH server)