import socket

s = socket.socket()     # get instance
host = socket.gethostname()     # get the hostname
port = 12345                # initiate port no above 1024
s.bind((host, port))        # bind host address and port together
s.listen()      # configure how many client the server can listen simultaneously

(connection, addr) = s.accept()     # accept new connection
print('Verbindung von ', addr)
while True:
    # receive data stream. it won't accept data packet greater than 1024 bytes
    data = connection.recv(1024).decode()
    if not data:
        # if data is not received break
        break
    print("from connected user: " + str(data))
    connection.send(data.upper().encode())
    #data = input(' -> ')
    #connection.send(data.encode())  # send data to the client
connection.close()      # close the connection