📝 Day 11 - Linux File Permissions & Ownership

🔐 On Day 11, I explored file permissions, group-based access, and the chmod/chown commands to control directory access—a critical skill for secure Linux administration.

📂 Step-by-Step Progress

✅ Directory Setup

• Created a new directory:

    mkdir /opt/devopsdir
  

• Verified permissions:

ls -ld /opt/devopsdir

👥 Group & Users Created a group:

groupadd devops

• Created users:

 useradd ansible
 useradd jenkins 
useradd aws
 useradd miles

🔄 Change Ownership of the group:

 chown -R ansible:devops /opt/devopsdir

🔧 Modify Permissions Removed execute permission for others:

 chmod o-x /opt/devopsdir

• Removed read permission for others:

chmod o-r /opt/devopsdir

• Gave write access to the group:

 chmod g+w /opt/devopsdir

🧪 Bonus:

• Created and assigned new directory:

mkdir /opt/webdata 
chown aws.devops /opt/webdata

• Tested permission variations:

    chmod 770 /opt/webdata # Full access to user & group, none for others
     chmod 000 /opt/webdata # No access to anyone
     chmod 777 /opt/webdata # Full access to everyone
  

📌 Key Takeaways

• ✅ Use chown to set owners and groups

• ✅ Use chmod to finely control permissions

• ✅ Understand rwx for user, group, others

• ✅ Always limit access with principle of least privilege

• ✅ Useful for securing apps, logs, and DevOps automation tasks

💬 Example Use Cases in DevOps

• Shared directory for deployment logs (group-access only)

• Locking sensitive config folders to specific automation users

• Securing volumes in container mounts (volumes:/opt/data:ro)

🚀 What’s Next? In Day 12, I

’ll explore sudo access, visudo, and privilege escalation policies used in real-world DevOps projects!