I just will write next code-fragment:

    import socket
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM, socket.IPPROTO_TCP)
    s.connect(('python.org', 80))
    print(
            'is my operation system using (by default) "tcpkeepalive"-algorithm for testing broken-connection? answer:',
            s.getsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE)
            )
    # answer is 0 (false) -- for all GNU/Linux


my previous code-example has 100-iteration -- only for we could catch the right-moment when testing (and for nothing else).