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Mastering Linux Network Administration

You're reading from   Mastering Linux Network Administration Master the skills and techniques that are required to design, deploy, and administer real Linux-based networks

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Product type Paperback
Published in Nov 2015
Publisher Packt
ISBN-13 9781784399597
Length 260 pages
Edition 1st Edition
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Author (1):
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Jay LaCroix Jay LaCroix
Author Profile Icon Jay LaCroix
Jay LaCroix
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Table of Contents (12) Chapters Close

Preface 1. Setting up Your Environment FREE CHAPTER 2. Revisiting Linux Network Basics 3. Communicating Between Nodes via SSH 4. Setting up a File Server 5. Monitoring System Resources 6. Configuring Network Services 7. Hosting HTTP Content via Apache 8. Understanding Advanced Networking Concepts 9. Securing Your Network 10. Troubleshooting Network Issues Index

Securing OpenSSH


OpenSSH is a wonderful tool; it's the Linux administrator's best friend. It saves you the trouble of having to walk into the server room and attach a monitor and keyboard in order to perform work on your network. Using any computer connected to the same network, you can pretty much do anything you want to as if you were standing right in front of the machine. The problem is that an unsecured SSH implementation gives miscreants the exact same luxury. Of all the things running on your network, SSH is definitely the one you want to give some major attention to.

The first and most common security tweak for SSH is to use only Version 2 of the protocol. To determine which version your Linux installation is using, grep the /etc/ssh/sshd_config file:

cat /etc/ssh/sshd_config |grep Protocol

If the answer is 1, you should edit this file and change the line that reads Protocol 1 to Protocol 2, and restart SSH. The reason this is important is because Protocol 1 has considerably weaker...

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