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Python 3 create ssh tunnel to socket1/14/2024 We can make an SSH context manager that takes care of doing all of the session setup and teardown, and we can ensure that the SSH session will be closed even if exceptions are raised. This is perfect for our SSH connection logic. Our code will look much cleaner if we can separate the setup/teardown code (opening the file, handling errors, closing the file) from the “doing something” code (reading or writing to the file). What is our end goal when we open a file? We either want to read the contents of the file or write something to the file. Open’s context manager takes care of this for us, without us having to manually handle it in our code.Ĭontext managers can be used for anything that requires a setup and teardown logic in-between the actual “body” of the code. No matter what happens in the body of the “with” block, the file handle will always get closed. When we call open using “with”, we are calling open’s context manager. Thankfully context managers take care of this administrative logic for us. This gets ugly, repetitive, and easy to forget. The code for the workflow described would look something like this: Take actions on the device (send commands, parse output, etc).The netmiko/paramiko object will use the network device attributes to establish an SSH session to the device. Instantiate a netmiko/paramiko object to which we pass in the network device object.The end result being that we create an object with the attributes required to connect to it. For example, you can read in the data from a json file containing your network device data, create a dictionary with key-value pairs, read it from a database, etc. This “network device” object contains attributes such as IP address, SSH port, username, password, and hostname. Create an object representing the device we are going to connect to.Establishing a connection to a device consists of the following workflow: The vendor specific logic in netmiko allows the responses received from each device to be parsed according to the device type (i.e Juniper devices are parsed differently than Arista)Ĭontext managers allow us to make the connection establishment process even simpler. netmiko simplifies connecting to a network device via SSH and taking actions on the device – it allows you to use simple method calls such as “send_command” to execute commands on a device, and will properly parse the response according to the device being connected to. This library adds some vendor specific logic to paramiko, which is the de-facto SSH library in Python. One of the simplest ways to connect to a network device programitically using Python is with Kirk Byer’s netmiko library. netmiko is a multi-vendor SSH Python library which makes connecting to network devices via SSH a breeze. Instead, this article is focused on showing how they can be used to facilitate the SSH connection logic to networking devices. Note: This post will not cover context manager details, as great explanations can already be found online. In this post, I will cover basic usage of Python’s context managers to connect to a network device using SSH. I will use them to abstract the connection establishment and teardown logic that is needed when making an SSH connection.
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