3. Communicating Between Nodes via SSH | Mastering Linux Network Administration

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Mastering Linux Network Administration

By : Jay LaCroix

4.6 (7)

Mastering Linux Network Administration

4.6 (7)

By: Jay LaCroix

Overview of this book

Linux is everywhere. Whether you run a home office, a small business, or manage enterprise systems, Linux can empower your network to perform at its very best. Armed with the advanced tools and best practice guidance of this practical guide, you'll be able to mold Linux networks to your will, empowering your systems and their users to take advantage of all that Linux-based networks have to offer. Understand how Linux networks function and get to grips with essential tips and tricks to manage them - whether you're already managing a networks, or even just starting out. With Debian and CentOS as its source, this book will divulge all the details you need to manage a real Linux-based network. With detailed activities and instructions based on real-world scenarios, this book will be your guide to the exciting world of Linux networking.

Preface

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Free Chapter

1. Setting up Your Environment

1. Setting up Your Environment

Getting started

Distributions to consider

Physical machines versus virtual machines

Setting up and configuring VirtualBox

Acquiring and installing Debian 8

Acquiring and installing CentOS 7

Summary

2. Revisiting Linux Network Basics

2. Revisiting Linux Network Basics

Understanding the TCP/IP protocol suite

Naming the network device

Understanding Linux hostname resolution

Understanding the net-tools and iproute2 suites

Manually managing network interfaces

Managing connections with Network Manager

Summary

3. Communicating Between Nodes via SSH

3. Communicating Between Nodes via SSH

Using OpenSSH

Installing and configuring OpenSSH

The OpenSSH config file

Understanding and utilizing scp

Generating public keys

Keeping SSH connections alive

Exploring an alternative to SSH – utilizing Mosh (mobile shell)

Summary

4. Setting up a File Server

4. Setting up a File Server

File server considerations

NFS v3 versus NFS v4

Learning the basics of Samba

Mounting network shares

Automatically mounting network shares via fstab and systemd

Creating networked filesystems with SSHFS

Summary

5. Monitoring System Resources

5. Monitoring System Resources

Inspecting and managing processes

Understanding load average

Checking available memory

Using shell-based resource monitors

Scanning used storage

Introduction to logging

Maintaining log size with logrotate

Understanding the systemd init system

Understanding the systemd journal

Summary

6. Configuring Network Services

6. Configuring Network Services

Planning your IP address layout

Installing and configuring a DHCP server

Installing and configuring a DNS server

Setting up an internal NTP server

Summary

7. Hosting HTTP Content via Apache

7. Hosting HTTP Content via Apache

Installing Apache

Configuring Apache

Adding modules

Setting up virtual hosts

Summary

8. Understanding Advanced Networking Concepts

8. Understanding Advanced Networking Concepts

Dividing your network into subnets

Understanding the CIDR notation

Implementing Quality of Service

Routing TCP/IP traffic

Creating redundant DHCP and DNS servers

Summary

9. Securing Your Network

9. Securing Your Network

Limiting the attack surface

Securing OpenSSH

Configuring the iptables firewall

Protecting system services with fail2ban

Understanding SELinux

Configuring Apache to utilize SSL

Deploying security updates

Summary

10. Troubleshooting Network Issues

10. Troubleshooting Network Issues

Tracing routing issues

Troubleshooting DHCP issues

Troubleshooting DNS issues

Displaying connection statistics with netstat

Scanning your network with Nmap and Zenmap

Installing missing firmware on Debian systems

Troubleshooting issues with Network Manager

Summary

Index

Index

The OpenSSH config file

When utilizing SSH for the first time, the .ssh directory will be created in your home directory. This directory contains useful files for your SSH client, which include known_hosts, id_rsa, and id_rsa.pub once you generate your keys (which we will do later). While we will discuss those files later on in this chapter, there is another file that the SSH client recognizes: config. This file is not created by default. If you create it yourself (following the proper syntax), then SSH will recognize it. So, what does this config file do? If you have one or more hosts that you connect to frequently, you can fill this file with the specifics for each host without having to enter the details each time. Let's look at an example ~/.ssh/config file.

Host icarus
Hostname 10.10.10.76
Port 22
User jdoe

Host daedalus
Hostname 10.10.10.88
Port 65000
User duser

Host dragon
Hostname 10.10.10.99
Port 22
User jdoe

For this file, SSH will recognize three hosts straight away: Icarus,...

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