从套接字读取的Python初始返回一些意外字符

Question

I have a Python socket server that I'm trying to read text commands from a line at a time, code is below. The first time it is run, line contains what look like some garbage characters before the data. On subsequent calls to readline I get the exact data I typed in from the telnet client (Putty). Why am I getting these first few apparent garbage characters. Eg if I type in _return_ , line contains \\u18\\u01\\u03d\\r\\n '

    HOST = ''
    PORT = 27001
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    s.bind((HOST, PORT))
    s.listen(1)
    while True:
        conn, address = s.accept()
        print 'Got new CLI connection'
        f = conn.makefile()
        f.flush()
        while True:
            try:
                self.PrintBanner(conn)
                self.PrintMenu(conn)
                line = f.readline()
                if line.lower()[:1] == 'd':
                    self.MenuFieldRequestStatus(conn)
                    f.readline()
            except:
                s.close()

Answer 1

You need to make sure and use "RAW" mode in this case. Otherwise, your telnet client is trying to discover and negotiate with a telnet server. See this link for more info:

3.6 Making raw TCP connections

You could probably switch "Telnet negotiation mode" to passive in the Telnet settings area too.