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Linux Command Line and Shell Scripting Techniques

Linux Command Line and Shell Scripting Techniques

By : Vedran Dakic, Jasmin Redzepagic
4.4 (5)
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Linux Command Line and Shell Scripting Techniques

Linux Command Line and Shell Scripting Techniques

4.4 (5)
By: Vedran Dakic, Jasmin Redzepagic

Overview of this book

Linux Command Line and Shell Scripting Techniques begins by taking you through the basics of the shell and command-line utilities. You’ll start by exploring shell commands for file, directory, service, package, and process management. Next, you’ll learn about networking - network, firewall and DNS client configuration, ssh, scp, rsync, and vsftpd, as well as some network troubleshooting tools. You’ll also focus on using the command line to find and manipulate text content, via commands such as cut, egrep, and sed. As you progress, you'll learn how to use shell scripting. You’ll understand the basics - input and output, along with various programming concepts such as loops, variables, arguments, functions, and arrays. Later, you’ll learn about shell script interaction and troubleshooting, before covering a wide range of examples of complete shell scripts, varying from network and firewall configuration, through to backup and concepts for creating live environments. This includes examples of performing scripted virtual machine installation and administration, LAMP (Linux, Apache, MySQL, PHP) stack provisioning and bulk user creation for testing environments. By the end of this Linux book, you’ll have gained the knowledge and confidence you need to use shell and command-line scripts.
Table of Contents (19 chapters)
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Working with open ports and connections

Checking open ports on our local and/or remote machine is often part of security and configuration auditing processes. It's something that we use to check if we can connect to some remote ports to verify that a service works, whether a firewall is configured properly, or whether routing works – just regular, everyday tasks. Of course, it can also be a part of some hacking processes, which often start by using nmap and similar utilities to check for open ports and OS fingerprints. But, let's check how we can use utilities such as netstat, lsof, ss, and nmap to do good for our network and security.

Getting ready

Keep the client1 virtual machine powered on and let's continue using our shell. Generally speaking, if we're doing this on Ubuntu, we need to install some packages such as traceroute and nmap using apt-get:

apt-get -y install traceroute nmap

If, however, we are using CentOS, we need to use yum or dnf...

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