Book Image

Linux for Networking Professionals

By : Rob VandenBrink
1 (1)
Book Image

Linux for Networking Professionals

1 (1)
By: Rob VandenBrink

Overview of this book

As Linux continues to gain prominence, there has been a rise in network services being deployed on Linux for cost and flexibility reasons. If you are a networking professional or an infrastructure engineer involved with networks, extensive knowledge of Linux networking is a must. This book will guide you in building a strong foundation of Linux networking concepts. The book begins by covering various major distributions, how to pick the right distro, and basic Linux network configurations. You'll then move on to Linux network diagnostics, setting up a Linux firewall, and using Linux as a host for network services. You'll discover a wide range of network services, why they're important, and how to configure them in an enterprise environment. Finally, as you work with the example builds in this Linux book, you'll learn to configure various services to defend against common attacks. As you advance to the final chapters, you’ll be well on your way towards building the underpinnings for an all-Linux datacenter. By the end of this book, you'll be able to not only configure common Linux network services confidently, but also use tried-and-tested methodologies for future Linux installations.
Table of Contents (20 chapters)
1
Section 1: Linux Basics
4
Section 2: Linux as a Network Node and Troubleshooting Platform
8
Section 3: Linux Network Services

DNS troubleshooting and reconnaissance

The main tool in Linux to troubleshoot DNS services is dig, which comes pre-installed in almost all Linux distributions. If you don't have dig in your distribution, you can install it with apt-get install dnsutils. The use of this tool is pretty simple, as can be seen here:

Dig <request value you are making> <the request type you are making>  +<additional request types>

So, to find name server records for a company (we'll check sans.org), we'll make an ns query against sans.org, as follows:

$ dig sans.org ns
; <<>> DiG 9.16.1-Ubuntu <<>> sans.org ns
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 27639
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 65494
;; QUESTION SECTION:
;sans.org.         ...