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- Herausgeber: Packt Publishing
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
Over 40 recipes to help you set up and configure Linux networks
About This Book
- Move beyond the basics of how a Linux machine works and gain a better understanding of Linux networks and their configuration
- Impress your peers by setting up and configuring a Linux server and its various network elements like a pro
- This is a hands-on solution guide to building, maintaining, and securing a network using Linux
Who This Book Is For
This book is targeted at Linux systems administrators who have a good basic understanding and some prior experience of how a Linux machine operates, but want to better understand how various network services function, how to set them up, and how to secure them. You should be familiar with how to set up a Linux server and how to install additional software on them.
What You Will Learn
- Route an IPv6 netblock to your local network
- Modify your named instance to support setting hostnames for your IPv6 addresses
- Use SSH for remote console access
- Configure NGINX with TLS
- Secure XMPP with TLS
- Leverage iptables6 to firewall your IPv6 traffic
- Configure Samba as an Active Directory compatible directory service
In Detail
Linux can be configured as a networked workstation, a DNS server, a mail server, a firewall, a gateway router, and many other things. These are all part of administration tasks, hence network administration is one of the main tasks of Linux system administration. By knowing how to configure system network interfaces in a reliable and optimal manner, Linux administrators can deploy and configure several network services including file, web, mail, and servers while working in large enterprise environments.
Starting with a simple Linux router that passes traffic between two private networks, you will see how to enable NAT on the router in order to allow Internet access from the network, and will also enable DHCP on the network to ease configuration of client systems. You will then move on to configuring your own DNS server on your local network using bind9 and tying it into your DHCP server to allow automatic configuration of local hostnames. You will then future enable your network by setting up IPv6 via tunnel providers.
Moving on, we'll configure Samba to centralize authentication for your network services; we will also configure Linux client to leverage it for authentication, and set up a RADIUS server that uses the directory server for authentication.
Toward the end, you will have a network with a number of services running on it, and will implement monitoring in order to detect problems as they occur.
Style and approach
This book is packed with practical recipes and a task-based approach that will walk you through building, maintaining, and securing a computer network using Linux.
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Seitenzahl: 199
Veröffentlichungsjahr: 2016
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Table of Contents
Linux Networking Cookbook
Linux Networking Cookbook
Copyright © 2016 Packt Publishing
All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews.
Every effort has been made in the preparation of this book to ensure the accuracy of the information presented. However, the information contained in this book is sold without warranty, either express or implied. Neither the author(s), nor Packt Publishing, and its dealers and distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this book.
Packt Publishing has endeavored to provide trademark information about all of the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information.
First published: June 2016
Production reference: 1220616
Published by Packt Publishing Ltd.
Livery Place
35 Livery Street
Birmingham B3 2PB, UK.
ISBN 978-1-78528-791-6
www.packtpub.com
Credits
Author
Gregory Boyce
Reviewer
Jean-Pol Landrain
Acquisition Editor
Sonali Vernekar
Content Development Editor
Onkar Wani
Technical Editor
Naveenkumar Jain
Copy Editor
Sneha Singh
Project Coordinator
Ulhas K
Proofreader
Safis Editing
Indexer
Hemangini Bari
Graphics
Kirk D'Penha
Production Coordinator
Shantanu N. Zagade
Cover Work
Shantanu N. Zagade
About the Author
Gregory Boyce is a technologist with nearly 20 years of experience in using and managing Linux systems. When he's not at work or spending time with his wife and two daughters, he is playing around with new technologies.
Gregory spent the last 15 years working at Akamai Technologies, where he has worked in roles ranging from Network Operations, Internal IT, Information Security, Software Testing, and Professional Services.
Currently, he heads up the Linux OS team that manages Akamai's custom Linux operating system, which runs on their massively distributed customer facing network.
I'd like to thank my wife, Vanessa, for all the support and Akamai for surrounding me with such a wonderful assortment of intelligent and interesting people.
About the Reviewer
Jean-Pol Landrain has a BSc degree in software engineering with a focus in network, real-time, and distributed computing. He gradually became a software architect with more than 18 years of experience in object-oriented programming, in particular with C++, Java/JEE, various application servers, and related technologies.
He works for Agile Partner, an IT consulting company based in Luxembourg. From early 2006 he became dedicated to the promotion, education, and application of agile development methodologies.
He has reviewed numerous books both for Manning and Packt Publishing about Docker, Git, Spring, and message-oriented middleware.
I would like to thank my fantastic wife, Marie, and my 9 year old daughter, Phoebe, for their daily patience regarding my passion for technology and the time I dedicate to it. I would also like to thank my friends and colleagues because a life dedicated to technology would be boring without the fun they bring to it.
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Preface
Network administration is one of the main tasks of Linux system administration. By knowing how to configure system network interfaces in a reliable and optimal manner, Linux administrators can deploy and configure several network services including file, web, mail, and servers while working in large enterprise environments.
What this book covers
Chapter 1, Configuring a Router, starts by getting you to manually configure the IP address information on your system and then properly configure the system to bring up its interfaces automatically. From there, we'll move on to extending our system to act as a router for your own network, including DHCP for dynamically configuring client systems.
Chapter 2, Configuring DNS, will cover setting up your internal DNS server for both resolving external hostnames for you, as well as hosting DNS records for your own domain.
Chapter 3, Configuring IPv6, will provide a brief introduction of IPv6. We'll configure a tunnel to provide IPv6 connectivity, implement firewalling using iptables6, and provide IPv6 addresses to the rest of your network.
Chapter 4, Remote Access, will look at methods for remotely interacting with your new network using OpenSSH and OpenVPN.
Chapter 5, Web Servers, will set up web servers hosting PHP code, using both the Apache HTTPD server and NGINX.
Chapter 6, Directory Services, will tell us how to use Samba 4 to create an Active Directory-compatible directory service for your network.
Chapter 7, Setting up File Storage, will give us several options to explore for hosting your own file storage, including Samba, NFS, and WebDAV.
Chapter 8, Setting up E-mail, will tell us how to set up an e-mail server. We'll talk about how e-mail works as a service, set SMTP and IMAP mail services, and enable some spam filtering.
Chapter 9, Configuring XMPP, will tell us how to configure our own XMPP based IM service, configure it to communicate with other XMPP services, and configure Pidgin as a client to utilize the service.
Chapter 10, Monitoring Your Network, will tell us how to start monitoring services on our network using Nagios.
Chapter 11, Mapping Your Network, will cover mapping out the network in order to discover what is actually there.
Chapter 12, Watching Your Network, will cover watching over our network through centralized logging and managing an intrusion detection system using Snort.
What you need for this book
For this book you'll need a copy of Linux, preferably Ubuntu 14.04.
You'll also want access to three computers to install Linux on. One of the servers will need to have three network cards built into it.
For this purpose, I would strongly recommend using Virtual machines (VMs). Virtual Box will allow you to do this for free and is available on Windows, Linux, or OS X. You may find that the commercial offerings from VMWare, Parallels, or Microsoft may provide better performance, however.
Who this book is for
This book is targeted at Linux system administrators who have a good basic understanding and some prior experience of how a Linux machine operates, but want to better understand how various network services function, how to set them up, and how to secure them. You should be familiar with how to set up a Linux server and how to install additional software on them.
Conventions
In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning.
Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "Modify /etc/default/isc-dhcp-server to add the interface which you should serve requests on."
A block of code is set as follows:
Any command-line input or output is written as follows:
New terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: "Under User Functions, click Create Regular Tunnel. You may create up to 5 tunnels."
Note
Warnings or important notes appear in a box like this.
Tip
Tips and tricks appear like this.
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Chapter 1. Configuring a Router
In this chapter, we will cover:
Introduction
This chapter introduces some of the basic networking concepts and the methods to utilize them on Linux systems. It provides us with a good base to build upon. We're going to start with two computers connected with a single network cable and work our way from there to configure a router to connect your network to the Internet.
Routers are devices that are configured to span multiple networks and forward packets between them as needed. They also perform Network Address Translation (NAT) in order to allow your private network to share a single public IPv4 address.
Setting up the physical network
Before we start configuring the networking within Linux, we need to physically connect the systems. The simplest configuration involves connecting the two computers with a single cable, although connecting them to a switch may make more sense for additional expansion. Once physically connected, we need to confirm that they are working as expected.
How to do it…
On each Linux system, use the ip command to check for a network link as shown:
Some people may choose to use ethtool, mii-tool, or mii-diag to perform the same action.
Make sure to run the same command on both the systems, especially if you're connecting to a switch rather than directly connecting the two systems.
How it works…
The first command brings up the network interface card (NIC). This activates the interface and allows it to start the process to check for a network link or electrical connection between the two systems.
Next, the show command gives you a bunch of information about the link. You should see a state showing UP. If it shows DOWN, then you have a link issue of some sort. This could be a disconnected/bad cable, a bad switch, or you forgot to bring up the network interface.
Configuring IPv4
Now that we've established a link between the machines, let's put some IP addresses on the systems so that we can communicate between them. For now, let's look at manually configuring IP addresses rather than auto-configuring them via DHCP.
How to do it…
We need to manually configure the IP addresses using the ip command. Let's start with server 1:
Now we need to perform the same action on server 2, but with 10.0.0.2/24 instead of 10.0.0.1/24.
How it works…
There are a few things in play here, so it probably makes sense to go through them one at a time.
First, let's start off by looking at the IP address that we're configuring. The 10.0.0.1 and 10.0.0.2 are a part of a series of netblocks set aside for private networks by RFC1918, IP Address Allocation for Private Internets. RFC1918 sets aside three large ranges, 10.0.0.0-10.255.255.255 (10.0.0.0/8), 172.16.0.0-172.31.255.255 (172.16.0.0/12), and 192.168.0.0-192.168.255.255 (192.168.0.0/16).
For our purpose, we're configuring 10.0.0.1/24, which is an IP range that includes 10.0.0.0-10.0.0.255. This includes 256 addresses, of which 254 are usable after setting aside 10.0.0.0 as the network address and 10.0.0.255 as the broadcast address. Both our systems get one IP in that range, which should allow them to communicate between them.
Next, we use the ip command to define an address on the eth0 device using one of the IP addresses in that range. You need to make sure that each machine in that range has a different IP address in order to prevent IP address conflicts, which would make communication between the two systems impossible and communication with different systems difficult.
Some people may be accustomed to seeing the ifconfig command rather than the ip command used here. While it will certainly do the job in most cases, net-tool (and its ifconfig command) has been deprecated by most distributions since the turn of the century, in favor of iproute2 and its ip command.
Once the commands have been run on both servers, you should be able to ping them from each other. Log in to 10.0.0.1 and run the following:
If everything is configured properly, you will be able to see successful ping responses at this point.
Configuring IPv4 permanently
In the previous section we configured the network interface, but this configuration is only valid while the system is up and running. A reboot will clear this configuration, unless you take steps to make sure that it is configured on each boot. This configuration will be specific to the distribution that you are running, although most distributions fall under either the Debian or Red Hat methods.
How to do it…
Let' see how it works in Debian/Ubuntu:
Let' see how it works in Red Hat/CentOS:
How it works…
Linux distributions are configured through init systems, such as Upstart, SystemD, or SysVInit. During the initialization process, the interfaces, or ifcfg-eth0 files, are used as a configuration for the networking setup scripts. These scripts then use the same ip commands, or possibly ifconfig commands to set up and bring up the network interface.
Connecting two networks
For our next step, we're going to add a second interface to server 1. In addition to 10.0.0.1/24 being configured on eth0, we're going to configure 192.168.0.1/24 on eth1. The second interface could just as easily be 10.0.1.1/24, but let's make sure that the networks are obviously different.
The systems should be configured similar to Figure 1:
How to do it…
Let's connect two networks:
How it works…
When you
