===========================
linux-nc-and-python-sockets
===========================

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   | **Source:**
     https://foxhop.net/f3b9a5c5-2f95-11f1-beb3-e86a64d24d78/linux-nc-and-python-sockets
   | **Snapshot:** 2026-06-15T11:13:27Z
   | **Generator:** Remarkbox ``50b9d1e``

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linux-nc-and-python-sockets
===========================

nc or netcat lets you create socket servers or connect to services via
sockets.

The nc man page is excellent. This first thing I tried was creating a
simple-chat like program between two terminals.

Simple nc chat application
==========================

Start listening (nc -l) for a connection on a port (31337).

**On terminal A**

.. container::
   :name: cb1

   ::

      nc -l 31337

Connect to (127.0.0.1) on a port (31337).

**On terminal B**

.. container::
   :name: cb2

   ::

      nc 127.0.0.1 31337

Like the man page suggests all text submitted on either terminal A or B
will appear on both terminals. Conventionally the server "listening" for
connections is typically labeled the server. In this case neither
terminal is a server because if either closes, both close...

Use python to interact with nc
==============================

On terminal A

.. container::
   :name: cb3

   ::

      nc -l 31337

On terminal b

.. container::
   :name: cb4

   ::

      python

      >>> import socket
      >>> s = socket.socket( socket.AF_INET, socket.SOCK_STREAM )
      >>> s.connect( ( 'localhost', 31337 ) )
      >>> s.send( 'python says hello nc' )
      20
      >>> s.recv( 30 )
      'nc says hello python\n'
      >>> # To learn more about sockets do:
      >>> help( s )
      >>> # when you are finished run s.close()

The constant socket.AF_INET creates a socket which allows us to connect
to an ip/name and port. The constant socket.AF_UNIX creates a socket
which allows us to connect via files? socket.SOCK_STREAM is the type of
socket (tcp/ip). socket.SOCK_DGRAM (data-gram or UDP)

--------------

| **Source:**
  https://foxhop.net/f3b9a5c5-2f95-11f1-beb3-e86a64d24d78/linux-nc-and-python-sockets
| **Snapshot:** 2026-06-15T11:13:27Z
| **Generator:** Remarkbox ``50b9d1e``