1. Age and Maturity

2. Scalability and Performance

• Traditional Linux permissions (owner/group/others) are discretionary access control (DAC), meaning users/processes can change permissions themselves.

• SELinux adds an extra layer of security that cannot be bypassed by users/processes, enforcing strict policies defined by the system administrator or security team.

• Helps contain compromised processes and reduce the impact of vulnerabilities by limiting what each process can do.

SELinux Modes

Common Package Management Tasks

1. Search for a Package

dnf search <package-name>

Example:

dnf search nginx

2. Install a Package

dnf install <package-name>

Example:



dnf install git

3. Check if a Package is Installed

dnf list installed <package-name>

Example:



dnf list installed httpd

4. Remove a Package

dnf remove <package-name>

Example:



dnf remove nginx

5. Update a Package

dnf update <package-name>

Example:



dnf update openssl

6. Upgrade All Packages

dnf upgrade

7. View Package Info

dnf info <package-name>

Example:



dnf info curl

8. List All Installed Packages

dnf list installed

9. Enable/Disable Repositories

Requires: dnf install dnf-plugins-core if config-manager is missing.

 10. Clean DNF Cache

dnf clean all

Red Hat OpenShift is a Kubernetes platform built for enterprises. It provides all the capabilities of Kubernetes (the open-source container orchestration system) but with:

• A built-in developer-friendly web UI

• Enterprise support and lifecycle management

• Integrated CI/CD, logging, and monitoring

• Security hardening (like SELinux, RBAC, OAuth, etc.)

• Tools for managing both infrastructure and applications

A cluster is a group of machines (physical or virtual), organized to work together, where:

• Some machines are control plane nodes (also called masters)

• Some are worker nodes, where applications actually run

Each cluster includes:

Here are some key points about RPM packages:

1. Format: RPM packages have a .rpm file extension and contain the compiled code, libraries, configuration files, and metadata necessary for software installation.

2. Package Management: RPM provides tools for installing, upgrading, and removing packages, as well as checking the status of installed software. The main command-line tool is rpm.

3. Dependencies: RPM packages can specify dependencies, ensuring that all required libraries and packages are installed before a package can be installed.

4. Verification: RPM can verify the integrity of installed packages and check for missing files or alterations, helping maintain system stability and security.

5. Database: RPM maintains a database of installed packages, allowing users to query and manage software easily.

6. Source RPMs: In addition to binary RPMs, there are source RPMs (SRPMs), which contain the source code and instructions for building the binary package. This allows for customization and recompilation of software.

7. Graphical Tools: While RPM is primarily a command-line tool, many graphical package managers, such as GNOME Software or KPackageKit, use RPM under the hood for package management.

Here are some key aspects:

1. Monolithic Kernel: The Linux kernel is monolithic, meaning it includes all the necessary drivers and services in one large program, which can lead to efficient performance.

2. Modular Architecture: It supports loadable modules, allowing developers to add or remove functionality dynamically without rebooting the system.

3. Processes and Memory Management: The kernel manages process scheduling, memory allocation, and ensures efficient execution of applications.

4. File Systems: It supports various file systems, enabling interaction with different types of storage devices.

5. Device Drivers: The kernel includes drivers for hardware devices, allowing communication between the operating system and hardware components.

6. Security: It provides features such as user permissions, access control, and security modules to enhance system security.

7. Community Development: The Linux kernel is developed collaboratively by a community of developers and organizations, with contributions from individuals and companies.

8. Kernel Versions: The kernel is regularly updated, with new versions introducing improvements, bug fixes, and new features.

However, CentOS does not provide official support from Red Hat.

sudo systemctl status firewalld