What this book covers

Chapter 1, Welcome to the Linux Family, consists of a short history of Linux and a description of various Linux distributions. Also, we provide some advice for selecting a Linux distribution for your organization.

Chapter 2, Basic Linux Network Configuration and Operations – Working with Local Interfaces, discusses network interface configuration in Linux, which can be a real stumbling block for many administrators, especially when the decision has been made that a server doesn't need a GUI. In this chapter, we'll discuss how to configure various network interface parameters, all from the command line, as well as lots of the basics of IP and MAC layer lore.

Chapter 3, Using Linux and Linux Tools for Network Diagnostics, covers diagnosing and resolving network problems, which is a daily journey for almost all network administrators. In this chapter, we'll continue the exploration that we started in the previous chapter, layering on TCP and UDP basics. With that in hand, we'll discuss local and remote network diagnostics using native Linux commands, as well as common add-ons. We'll end this chapter with a discussion of assessing wireless networks.

Chapter 4, The Linux Firewall, explains that the Linux firewall can be a real challenge for many administrators, especially since there are multiple different "generations" of the iptables/ipchains firewall implementation. We'll discuss the evolution of the Linux firewall and implement it to protect specific services on Linux.

Chapter 5, Linux Security Standards with Real-Life Examples, covers securing your Linux host, which is always a moving target, depending on the services implemented on that host and the environment it's deployed to. We'll discuss these challenges, as well as various security standards that you can use to inform your security decisions. In particular, we'll discuss the Center for Internet Security (CIS) Critical Controls, and work through a few of the recommendations in a CIS Benchmark for Linux.

Chapter 6, DNS Services on Linux, explains how DNS works in different instances, and how to implement DNS services on Linux, both internally and internet-facing. We'll also discuss various attacks against DNS, and how to protect your server against them.

Chapter 7, DHCP Services on Linux, covers DHCP, which is used to issue IP addresses to client workstations, as well as to "push" a myriad of configuration options to client devices of all kinds. In this chapter, we'll illustrate how to implement this on Linux for traditional workstations, and discuss things you should consider for other devices, such as Voice over IP (VoIP) phones.

Chapter 8, Certificate Services on Linux, covers certificates, which are often viewed as "the bogeyman" in many network infrastructures. In this chapter, we try to demystify how they work, and how to implement a free certificate authority on Linux for your organization.

Chapter 9, RADIUS Services for Linux, explains how to use RADIUS on Linux as the authentication for various network devices and services.

Chapter 10, Load Balancer Services for Linux, explains that Linux makes a great load balancer, allowing "for free" load balancing services tied to each workload, rather than the traditional, expensive, and monolithic "per data center" load balancing solutions that we see so often.

Chapter 11, Packet Capture and Analysis in Linux, discusses using Linux as a packet capture host. This chapter covers how to make this happen network-wise, as well as exploring various filtering methods to get the information you need to solve problems. We use various attacks against a VoIP system to illustrate how to get this job done!

Chapter 12, Network Monitoring Using Linux, covers using Linux to centrally log traffic using syslog, as well as real-time alerting on keywords found in logs. We also have a discussion on logging network traffic flow patterns, using NetFlow and related protocols.

Chapter 13, Intrusion Prevention Systems on Linux, explains that Linux applications are used to alert on and block common attacks, as well as adding important metadata to traffic information. We explore two different solutions in this regard, and show how to apply various filters to uncover various patterns in traffic and attacks.

Chapter 14, Honeypot Services on Linux, covers using honeypots as "deception hosts" to distract and delay your attackers, while providing high-fidelity alerts to the defenders. We also discuss using honeypots for research into trends in malicious behavior on the public internet.