Initial new file 'linux_system_administration.md'

Content/Linux/README.md

@@ -77,6 +77,21 @@ Topics covered:
 - Managing processes (`kill`, `nice`, `renice`)
 - Background and foreground processes
 
+---
+
+## Linux System Administration
+
+Learn how to manage administrative tasks on Linux systems. Check out the [Linux System Administration Guide](linux_system_administration.md).
+
+Topics covered:
+
+- Managing users and groups** – Learn how to create, modify, and delete users and groups, and how to manage their permissions on the system.
+- Configuring sudo for safe administrative access** – Configure `sudo` to grant elevated privileges without exposing the root account. Learn how to safely edit the `/etc/sudoers` file and set up specific permissions.
+- Setting up automation with sudoers** – Automate tasks like Ansible playbooks by editing the `sudoers` file to grant required permissions without needing a password.
+- System security practices** – Understand best practices for securing your system, such as configuring firewalls, applying patches, and minimizing root access.
+- Basic troubleshooting techniques** – Common tools and methods for diagnosing and fixing issues on Linux systems.
+
+
 ---
 
 ## Getting Started

Content/Linux/linux_file_management.md

@@ -138,7 +138,9 @@ Now convert this number to 10-bases number:
 
 Now simply add up the values for each permission that is granted, and use that as the digit in the corresponding position. For example:
 
-`rwxrw-rw-` would be represented as 766 in octal notation. 7 for `rwx` of the user, 6 for `rw-` of the group, 6 again of `rw-` for others.
+`rwxrw-rw-` would be represented as 766 in octal notation. 7 for `rwx` of the user, 6 for `rw-` of the group, 6 again of `rw-` for others.  
+
+For your convince, you can also use this website: https://chmod-calculator.com/
 
 #### Default permissions
 

Content/Linux/linux_system_administration.md

@@ -0,0 +1,76 @@
+# Linux System Administration
+
+This guide explains how to grant `sudo` privileges for automated tasks in Linux-based systems.
+
+## The Root User
+
+The **root user** is the administrative user in Linux-based operating systems, including Ubuntu. The root user has unrestricted access to all system files, processes, and settings, allowing it to perform any operation, including modifying crucial system files.
+
+## Granting Full-Time Sudo Access for Automation
+
+To allow automated tasks to run with elevated privileges, you can modify the `/etc/sudoers` file. Always use the `visudo` command to edit this file to avoid syntax errors. 
+
+### Editing the Sudoers File
+
+1. Open the sudoers file using `visudo`:
+
+    ```console
+    sudo visudo
+    ```
+
+2. Add the necessary permissions for your automation tasks. For example, to grant Ansible playbooks permission to execute certain commands without needing a password, add the following line to the sudoers file:
+
+    ```console
+    ansible ALL=(ALL) NOPASSWD: /bin/sh -c echo BECOME-SUCCESS-*, \
+                                 /usr/bin/python /tmp/ansible/ansible-tmp-*
+    ```
+
+    This configuration allows the Ansible user to run specific commands without needing to enter a password each time.
+
+### Verifying the sudoers File
+
+After editing the sudoers file, always verify that the syntax is correct before saving the file. This can be done using the `visudo -c` command. 
+
+```console
+sudo visudo -c
+````
+
+The output should be:
+
+```console
+/etc/sudoers: parsed OK
+/etc/sudoers.d/README: parsed OK
+```
+
+If you see any errors, the `visudo` tool will indicate them, preventing misconfiguration.
+
+### Example of a Correct sudoers File
+
+Here’s an example of how your `sudoers` file might look after adding the necessary automation permissions:
+
+```console
+# User privilege specification
+root    ALL=(ALL:ALL) ALL
+
+# Members of the admin group may gain root privileges
+%admin ALL=(ALL) ALL
+
+# Allow members of group sudo to execute any command
+%sudo   ALL=(ALL:ALL) ALL
+
+# Grant Ansible full-time sudo access to specific tasks
+ansible ALL=(ALL) NOPASSWD: /bin/sh -c echo BECOME-SUCCESS-*, \
+                             /usr/bin/python /tmp/ansible/ansible-tmp-*
+
+# Include additional sudoers configuration from files in the /etc/sudoers.d directory
+@includedir /etc/sudoers.d
+```
+
+### Best Practices and Security Considerations
+
+* **Limit Access**: Only grant the minimal set of privileges needed for automation tasks. Avoid providing unnecessary access.
+* **Avoid Full Root Access**: Instead of granting full root access to automation users, restrict them to specific commands that are necessary for the task.
+* **Always Validate the sudoers File**: After making changes to the sudoers file, always run `visudo -c` to ensure there are no syntax errors. Misconfigurations could lock you out of critical tasks.
+* **Use `sudo` for Automation**: Avoid using the root account directly for automation. Instead, configure `sudo` to a uniqe application user and grant only the necessary privileges.
+
+By following these guidelines and using the `visudo -c` command to validate your sudoers file, you ensure that your automation tasks can run smoothly and securely.