从Telnet会话内部进行Telnet（Python）

Question

I am trying to telnet to a remote device from another remote device, doing a nested telnet using telnetlib. While I can easily communicate with the first device, I am not able to get the output from the second device. Below is my code, am I doing this correctly?

import telnetlib

HOST = "firstDevice"
user = "lab"
password = "lab"

tn = telnetlib.Telnet(HOST)

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

#Nested telnet
tn2 = telnetlib.Telnet("secondDevice") 
tn2.read_until("#")   
tn2.write("sh clock\n")

#Close tn2
tn2.write("exit\n")
print tn2.read_all()

#Close tn
tn.write("exit\n")
print tn.read_all()

Edit 1

import telnetlib

HOST = "firstDevice"
user = "lab"
password = "lab"

tn = telnetlib.Telnet(HOST)

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

#Nested telnet
tn.write("telnet secondDevice\n") 
tn.write("sh clock\n")

#Close nested session
tn.write("exit\n")

#Close tn
tn.write("exit\n")
print tn.read_all()

Answer 1

You are not doing a nested connection in your code. You are just connecting to two different computers from localhost, but apparently you can not actually connect to the second one. To do a nested Telnet to the second host, you have to tell the first one to telnet to the second one: replace tn2 = telnetlib.Telnet("secondDevice") with

tn.write("telnet secondDevice\n")

Since you have a nested connection, all your localhost should see is tn . You can get rid of the tn2 object entirely. All interaction with the second device will be done by sending strings to the first device, which is in a session connected to the second device.