Python is a versatile scripting language that you can use to automate many tasks, including network administration. In this article, we’ll show you how to use Python to automate the task of telnetting into a network device.
We’ll start by writing a simple Python script that will telnet to a device and run a few commands. Then, we’ll use the Python module pexpect to automate the task of logging in and running commands. Finally, we’ll show you how to use the fabric module to automate the task of configuring multiple devices over SSH.
Telnet is a network protocol that allows you to connect to a remote device and run commands on that device. In order to use telnet, you need to have a telnet client installed on your computer. On Linux and Mac OS X, you can use the built-in telnet command. On Windows, you can install the Telnet Client feature from the Control Panel.
Once you have a telnet client installed, you can use it to connect to a remote device by running the following command:
telnet [hostname or IP address] [port]
For example, to connect to a device with the hostname my-device.example.com on port 23, you would run the following command:
telnet my-device.example.com 23
When you connect to a device using telnet, you will be prompted for a username and password. Once you have entered the correct credentials, you will be logged in and you will be able to run commands on the remote device.
In order to automate the task of telnetting into a device, we can use the Python module pexpect. Pexpect is a Python module for spawning child processes and interacting with them.
We can use pexpect to automate the task of logging in and running commands on a remote device. The first step is to install pexpect using the following command:
pip install pexpect
Once pexpect is installed, we can use it to write a Python script that will telnet to a device and run a few commands. The following script will telnet to a device with the hostname my-device.example.com on port 23 and run the show version command:
import pexpect
child = pexpect.spawn(‘telnet my-device.example.com 23’)
child.expect(‘Username:’)
child.sendline(‘my-username’)
child.expect(‘Password:’)
child.sendline(‘my-password’)
child.expect(‘>’)
child.sendline(‘show version’)
child.expect(‘>’)
print child.before
child.sendline(‘exit’)
In this script, we start by importing the pexpect module.
Other related questions:
How do I automate in telnet?
You can use a tool like Expect to automate Telnet sessions.
How do I create a Telnet connection using Python?
import telnetlib
tn = telnetlib.Telnet(“hostname”)
tn.write(“username\r
“)
tn.read_until(“Password: “)
tn.write(“password\r
“)
tn.read_all()
What is Read_until in telnet?
Read_until is a function in the telnet library that reads from the telnet connection until a specified string is encountered.
How do I run a telnet command?
To run a telnet command, you must first open a telnet session. To do this, open a command prompt and type “telnet” followed by the IP address or hostname of the machine you wish to connect to. For example, to connect to a machine with the IP address 192.168.1.1, you would type:
telnet 192.168.1.1
Once you are connected, you can type in any telnet command you wish to execute.