telnet_repl.py

import usocket as socket
telnet_server_fd = socket.socket()
telnet_server_fd.bind(("0.0.0.0", 23))
telnet_server_fd.listen(2)
telnet_client_fd = None
def setup_telnet(s):
  global telnet_client_fd
  telnet_client_fd, addr = telnet_server_fd.accept()
  uterminal.register(telnet_client_fd)
  telnet_client_fd.setblocking(False)
  print("here's comes a telnet client {}".format(addr))
telnet_server_fd.setsockopt(socket.SOL_SOCKET, 20, setup_telnet)