http://dept-info.labri.fr/~thibault/enseignements.html#Reseau

#!/usr/bin/python3
import sys
import socket
 
HOST = 'time-c.nist.gov'
PORT = 13                  # daytime  
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s.sendto(b'', (HOST,PORT))
d = s.recvfrom(1024)
reply = d[0]
addr = d[1]
print 'Server reply : ' + reply
s.close()
print ('Received', data)

#!/usr/bin/python3
import sys
import socket
 
HOST = 'www.labri.fr'     
PORT = 80                 
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((HOST, PORT))
s.sendall(b'GET /\r\n\r\n')
data = s.recv(1024)
s.close()
print ('Received', data)

Voici un echo server…

# Echo server program
import socket
 
HOST = ''                 # Symbolic name meaning all available interfaces
PORT = 50007              # Arbitrary non-privileged port
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
    s.bind((HOST, PORT))
    s.listen(1)
    conn, addr = s.accept()
    with conn:
        print('Connected by', addr)
        while True:
            data = conn.recv(1024)
            if not data: break
            conn.sendall(data)

• https://docs.python.org/3/library/socket.html
• https://docs.python.org/3/library/select.html
• https://docs.python.org/3/library/threading.html
• https://docs.python.org/3/library/stdtypes.html#str