Python telnet 连接成功

Question

I'm wondering if it is possible to know if my telnet connection is successful?

So, if I'm connected to my switch and if I could write commands

telnet = telnetlib.Telnet(IP)
telnet.read_until(b"User Name:")
telnet.write(b"LOGIN\n")
telnet.read_until(b"Password:")
telnet.write(b"PASSWORD\n")
# Here I want to know if I'm connected

Answer 1

You could go this way:

def is_connected(telnet_obj ):
    answer = telnet_obj.read_all()
    if "connected" in answer:             #this test condition is not real is an example
        return True
    else:
        return False

If you observe what yout router/switch returns you can test for that condition. In this case testing for the presence of a string or lack in the answer variable.

Answer 2

Don't use read_all if you plan on writing something after authentication. It blocks the connection until EOF is reached / connection is closed.

First check the output telnet server is giving when an authentication is successful using putty or something else. read_untill the string to be matched after authentication.

telnet = telnetlib.Telnet(IP)
telnet.read_until(b"User Name:")
telnet.write(b"LOGIN\n")
telnet.read_until(b"Password:")
telnet.write(b"PASSWORD\n")

telnet.read_untill("string to be matched")