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In this chapter, you will use Python’s SSH libraries, paramiko and netmiko, to control your networking devices. paramiko is what Ansible relies on for SSH connection management to network devices, and netmiko is an engineer-friendly version of paramiko as netmiko also relies on paramiko. By studying how these network modules work, you can learn the inner workings of other applications relying on these network modules. In the first half of this chapter, you will learn to replace basic network engineer manual tasks using Python scripts and the paramiko library. In the second half of this chapter, you will learn to write Python scripts using the netmiko library. Once you master how to use these SSH modules, you can apply them to your work immediately. These SSH labs will serve as the cornerstones in developing the IOS XE upgrade application at the end of this book.

Secure shell is a network protocol for the creation of encrypted connections. In its original and purest form, it is used to open a remote terminal and execute commands. However, the protocol can also be used for file transfer (SCP, SFTP); as an encrypted transport protocol for other, possible less strongly secured protocols; and for port forwarding—the redirection of requests for certain ports to ports on other servers—a technique often used to allow machines on different sides of a firewall to communicate.

Accessing UNIX-like servers remotely is almost universally done these days by SSH (Secure Shell). SSH is so popular that the rare times that it isn’t used (and something like a Telnet client is used instead) must show up on graphs as the tiniest of the smallest fractions of a percent. Personally, I rarely use SCP (Secure Copy); instead I use sFTP (Secure File Transfer Protocol) for most of my manual file transfers. The clever sFTP functionality runs as a subsystem of SSH, which adds encryption to the old-school file transfer protocol (FTP) to keep login details and transactional information safer during transit.

Most Linux computers operate in a connected world. Therefore, configuring the network board is of highest importance. In this chapter, you’ll first learn how to give your computer an IP address and related information. You’ll also learn about some useful tools that will help you in analyzing and troubleshooting a failing network connection. The last part of this chapter is about Secure Shell (SSH), which helps you make secured connections to other computers.

In this chapter, you’ll learn all there is to know about networking in SLES. We’ll cover the required information about manual network configuration, which makes clear which commands to use and which not to. Then you’ll read how to perform configuration automated from YaST. You’ll also learn which configuration files are related. Next, you’ll read how the completely new wicked tool is used to configure network settings, as an alternative to the approach that can be taken using YaST. At the end of the chapter, you’ll discover how to set up and work with Secure Shell (SSH), for secure remote network connections.