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Managing and Troubleshooting File and Directory Permissions in Linux

Course

Intro Video

Photo of Rob Marti

Rob Marti

Linux Training Architect I in Content

Rob is proudly from Huntsville, Texas (not Alabama). He spends his spare time enjoying family and nerding out with video games and Magic: The Gathering. He’ll never again live in a part of the country where it snows after growing up in Maryland and suffering through one blizzard too many. I've held many certifications over the years including Red Hat's Clustering, Performance Tuning, Satellite, and a few others.I'm excited to start this new course in my career and help serve the Community here at Linux Academy!

Length

03:22:49

Difficulty

Beginner

Videos

14

Hands-on Labs

5

Course Details

The interactions among the different permission schemes in Linux can be a little bit of a "magic cloud" to some. This course aims to alleviate some of that confusion, and gives tips on how to troubleshoot permission errors that are commonly seen. We'll cover "normal" (octal) permissions, ACLs, SELinux configurations, and some other special permission settings that aren't as commonly used.

Syllabus

Managing and Troubleshooting File and Directory Permissions

Course Introduction

Course Introduction

00:01:03

Lesson Description:

Welcome to Managing and Troubleshooting File and Directory Permissions. This video will have a quick overview of what we're going to talk about and then I'll introduce myself.

Understanding Octal Permissions in Linux

What are Octal Permissions?

00:11:09

Lesson Description:

To understand how to manage and troubleshoot permissions, we first need to make sure we understand the baseline of permissions. Octal permissions are what we see every day with commands like ls and chmod. This lesson will give a lot of information on what they are and how to manipulate them, in addition to some information on troubleshooting.

User Permissions vs. Group Permissions

00:07:56

Lesson Description:

When discussing permissions, it's useful to know about and have examples of what the differences between user and group permissions are. Seeing some examples of issues that can come up if permissions are incorrect is also handy.

Understanding `umask`

00:04:22

Lesson Description:

When discussing permissions in Linux, it's always useful to know where we started from. Default permissions are fine, but how do we customize those without having to change every file after creation? The umaskcommand will help with that, and in this lesson we learn how.

Permissions on Links

00:06:05

Lesson Description:

Symlinks and hard links are both very useful, and can also create issues while troubleshooting. This lesson will demystify some of the confusion surrounding links and how permissions work with them.

Special Interactions Based on the `root` User

00:05:05

Lesson Description:

The root user is powerful, but using it to troubleshoot permission issues can cause trouble, because of the all-powerful access that UID 0 bestows. This lessons goes through some of those issues and shows how they can come up, and also shows a method to run a shell as a "special" user like apache to assist in troubleshooting.

Hands-on Labs are real live environments that put you in a real scenario to practice what you have learned without any other extra charge or account to manage.

00:15:00

Linux Access Control Lists

Working with `getfacl` and `setfacl`

00:14:34

Lesson Description:

Linux Access Control Lists (ACLs) are an amazing tool we can use to supplement octal permissions. This lesson goes through what ACLs are, how to check the current settings, and some common pitfalls when using them.

Understanding the Interaction between ACLs and Octal Permissions

00:04:11

Lesson Description:

Understanding the interactions between ACLs and octal permissions is important. It's a good skill to have when troubleshooting permission issues where ACLs may be involved. This lesson goes over some more interactions, including when root tries to access ACL protected files.

Hands-on Labs are real live environments that put you in a real scenario to practice what you have learned without any other extra charge or account to manage.

00:30:00

SELinux

Understanding SELinux Labels

00:09:36

Lesson Description:

One of the most referenced challenges when it comes to permission issues is SELinux. Many administrators just set it to Permissive or Disabled so it doesn't get in the way. However, learning a few different things would allow them to run it as Enabled and have a more secure system overall. This lesson covers SELinux labels and contexts.

Understanding SELinux Booleans

00:08:49

Lesson Description:

SELinux Booleans control how processes can access files on a Linux system, so understanding how to manipulate them and what to look for is an important skill for Linux Administrators. This lesson covers that and walks through an example with http.

Interactions Among Different Permission Schemes

00:03:47

Lesson Description:

When looking at different permission schemes it's important to understand how they interact to determine how best to secure a file. This lesson covers the interactions between SELinux and octal/ACL permissions.

Hands-on Labs are real live environments that put you in a real scenario to practice what you have learned without any other extra charge or account to manage.

00:30:00

Special Bits

What are Special Bits?

00:10:00

Lesson Description:

Special bits are permission bits set using octal permissions that manipulate how the kernel interacts with the file. Some of them change what user or group a process runs as, while another changes how users can interact with files inside a directory. This lesson goes over them.

Special Attributes

00:03:25

Lesson Description:

Outside of file and directory permissions, there's another way to manipulate how the kernel interacts with a file. Special attributes can manipulate how a file is stored, among other things. This lesson goes over how to manipulate those attributes.

Hands-on Labs are real live environments that put you in a real scenario to practice what you have learned without any other extra charge or account to manage.

00:15:00

Hands-on Labs are real live environments that put you in a real scenario to practice what you have learned without any other extra charge or account to manage.

00:45:00

Conclusion

Conclusion

00:00:58

Lesson Description:

Welcome to the end of the course! In this video we'll wrap things up and go over what we've learned.

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