Book Image

Mastering Linux Security and Hardening

By : Donald A. Tevault
Book Image

Mastering Linux Security and Hardening

By: Donald A. Tevault

Overview of this book

This book has extensive coverage of techniques that will help prevent attackers from breaching your system, by building a much more secure Linux environment. You will learn various security techniques such as SSH hardening, network service detection, setting up firewalls, encrypting file systems, protecting user accounts, authentication processes, and so on. Moving forward, you will also develop hands-on skills with advanced Linux permissions, access control, special modes, and more. Lastly, this book will also cover best practices and troubleshooting techniques to get your work done efficiently. By the end of this book, you will be confident in delivering a system that will be much harder to compromise.
Table of Contents (15 chapters)
Title Page
Packt Upsell

Using ACLs to access files in the shared directory

As things currently stand, all members of the marketing group have read/write access to all other group members' files. Restricting access to a file to only specific group members is the same two-step process that we've already covered. 

Setting the permissions and creating the ACL

First, Vicky sets the normal permissions to allow only her to access her file. Then, she'll set the ACL:

[vicky@localhost marketing]$ echo "This file is only for my good friend, Cleopatra." > vicky_file.txt

[vicky@localhost marketing]$ chmod 600 vicky_file.txt

[vicky@localhost marketing]$ setfacl -m u:cleopatra:r vicky_file.txt

[vicky@localhost marketing]$ ls -l
total 4
-rw-rw-r--. 1 charlie marketing 0 Nov 13 15:59 charlie_file.txt
-rw-r-----+ 1 vicky marketing 49 Nov 13 16:24 vicky_file.txt

[vicky@localhost marketing]$ getfacl vicky_file.txt
# file: vicky_file.txt
# owner: vicky
# group: marketing