5. Monitoring System Resources | 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

Understanding load average

For a Linux administrator, load average is one of the most important concepts you'll ever learn. While you may know already that this number represents how much load your system is experiencing, it also represents trending performance as well. Using this number, you'll be able to determine whether your system is being overwhelmed or it's recovering and calming down. Essentially, the load average consists of three numbers, each representing the average load of the system over a specific time frame. The first number represents one minute, the second represents five minutes, and the third represents 15 minutes. There are many ways in which you can view your load average, and it will also be displayed in most system monitors available for Linux. One way to view your load average in a snap is to execute the following command:

cat /proc/loadavg

Viewing the load average

A simpler technique is to use the uptime command. Though the main purpose of the uptime command is to...

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