从python中的telnet会话进行Telnet

Question

Is it possible to telnet to a server and from there telnet to another server in python? Since there is a controller which I telnet into using a username and password, and from the controller command line I need to login as root to run linux command. How would I do that using python?

I use the telentlib to login into router controller but from the router controller I need to log in again to get into shell. Is this possible using python?

Thanks!

Answer 1

Just checked it with the hardware I have in hand & telnetlib. Saw no problem. When you are connected to the first device just send all the necessary commands using telnet.write('cmd') . It may be sudo su\\n , telnet 192.168.0.2\\n or whatever else. Telnetlib keeps in mind only its own telnet connection, all secondary connections are handled by the corresponding controllers.

Answer 2

Have you looked into using expect (there should be a python binding); basically, what I think you want to do is:

1. From your python script, use telnetlib to connect to server A (pass in username/password).
2. Within this "socket", send the remaining commands, eg "telnet serverB" and use expect (or some other mechanism) to check that you get back the expected "User:" prompt; if so, send user and then password and then whatever commands, and otherwise handle errors.

This should be very much doable and is fairly common with older stuff that doesn't support a cleaner API.

Answer 3

You can use write() to issue the sudo command.

tn.write("sudo\n")

You could also use read_until() to help with the credentials.

tn.read_until("login: ")
tn.write(user + "\n")
if password:
    tn.read_until("Password: ")
    tn.write(password + "\n")