22 Dec 2019  -  Fun with UDP on a Nix Box.

So Ive yet to learn much of anything about
Internet protocols. While idly poking around the
other night, I came across something called UDP
or User Datagram Protocol. From what little Ive
read about it, [1][2] it looks ideal for several
things including private chatting and sending
in data from remote sources  like a Raspberry Pi
sensor suite.  First off, youll need to choose a
port for your UDP connection. I chose 3497 which
is unofficially reserved for The PlayStation
Network. Having ZERO interest in the Sony
PlayStation, this suits me fine.  Then its time
to set up port forwarding on your router for that
specific port. This is straightforward. Consult
your routers docs.  Thats it for the underlying
infrastructure. Simple, Yeah? Now well be making
our test connection with one of those clever
little Linux Swiss Army Knives. This one's called
netcat. Netcat can do A LOT of stuff. Well be
using it twice.

Open a terminal window and type the command:
  nc -luk 3479 # Listening...
  Recall that 3479 is the port I chose above
  -l means to listen to the port
  -u means we're dealing with UDP connections
  -k means to keep listening after a sender
     disconnects

Now open a second terminal and type:
  nc -u localhost 3479 # Making Connection
  -u means we're dealing with a UDP connection
  you can substitute an ip or url for localhost 

Hitting [ENTER] in both cases will cause the
cursor to sit there, blinking expectantly
on a new line. In that second console type
something. Hello World is fine. If all went well,
you should see the text appear in the first
terminal. Continue typing until you get bored.
End your fun with [CRTL]+C in the second console.
Terminal One will happily continue looking for
new connections until you close netcat there.

Wow. Its the little things that tickle my
simple brain! I hope this gets some creative
juices flowing out there. Best, -Tim

[1]
https://searchnetworking.techtarget.com/definition/UDP-User-Datagram-Protocol

[2]
https://linux.die.net/man/1/nc

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* AS ALWAYS, IF I'VE MIS-SPOKE *
* HERE AND PROVIDED INACCURATE *
* INFO BECAUSE OF MY IGNORANCE *
* KINDLY LET ME KNOW.  THANKS! *
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