import socket

myserver = socket.socket()
hostname = myserver.gethostname()
port = 12345
myserver.bind((hostname, port))
myserver.listen()

while True:
    (connection, addr) = myserver.accept()
    msg_from_client = myserver.recv(1024)
    in_capital_letters = msg_from_client.upper()
    connection.send(in_capital_letters.encode('utf-8'))
    connection.close()