output.py

chars = [chr(i) for i in range(32, 127)]

for line in range(1, 9):
    for col in range(72):
        char = chars[(line + col) % len(chars)]
        print(char, end='')

    print()

tcp.py

import threading
import socket
from itertools import count

CHARS = [chr(i).encode('ascii') for i in range(32, 127)]
NEWLINE = '\r\n'.encode('ascii')
PORT = 19
WIDTH = 72


def generate(client):
    for line in count(1):
        try:
            for column in range(WIDTH):
                char = CHARS[(line + column) % len(CHARS)]
                client.send(char)

            client.send(NEWLINE)
        except Exception:
            client.close()
            break


def server():
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

    sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, True)
    sock.bind(('', PORT))
    sock.listen()

    while True:
        client, _ = sock.accept()
        thread = threading.Thread(target=generate, args=(client,))

        thread.start()


if __name__ == '__main__':
    server()

udp.py

import socket
from itertools import count

BUFFER_SIZE = 4096
CHARS = [chr(i).encode('ascii') for i in range(32, 127)]
MAX = 511
NEWLINE = '\r\n'.encode('ascii')
PORT = 19
WIDTH = 72


def generate():
    lines = count(1)
    reply = b''

    while len(reply) < MAX:
        line = next(lines)

        for column in range(WIDTH):
            reply += CHARS[(line + column) % len(CHARS)]

        reply += NEWLINE

    return reply[:MAX]


def server():
    reply = generate()
    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

    sock.bind(('', PORT))

    while True:
        _, address = sock.recvfrom(BUFFER_SIZE)

        sock.sendto(reply, address)


if __name__ == '__main__':
    server()