CentOS Technology Intelligence

What is CentOS?

CentOS (Community Enterprise Operating System) was a free, enterprise-grade Linux distribution derived from Red Hat Enterprise Linux (RHEL) source code. For over 15 years, CentOS provided a stable, no-cost alternative to RHEL for servers and enterprise workloads.

In 2020, Red Hat shifted CentOS to CentOS Stream, a rolling-release development preview of RHEL rather than a downstream rebuild. CentOS Linux 7 reaches end-of-life in June 2024, and CentOS 8 ended December 2021. Alternatives include Rocky Linux, AlmaLinux, and Oracle Linux.

CentOS remains widely deployed on existing infrastructure. Its RHEL compatibility means binary-compatible packages, enterprise-grade stability, and 10-year support cycles. Many organizations continue running CentOS 7 or have migrated to CentOS successors.

CentOS Architecture

RHEL Based: Binary compatible with Red Hat Enterprise Linux. Same packages and patches. Enterprise-grade stability. Predictable behavior.

YUM/DNF: Package management with yum (CentOS 7) or dnf (CentOS 8+). RPM packages. Repository-based updates. Dependency resolution.

SELinux: Security-Enhanced Linux mandatory access control. Process confinement. Fine-grained permissions. Enterprise security.

systemd: Service and system management. Unit files for services. Journal logging. Target-based boot.

Long Lifecycle: 10-year support for major versions. Security updates throughout. Stable ABI. Enterprise planning.

Minimal Defaults: Lean server installations. Add only what's needed. Smaller attack surface. Efficient resource use.

CentOS Use Cases

Enterprise Servers: RHEL-compatible production servers. cPanel and Plesk hosting. Web and application servers. Database hosts.

Data Centers: Bare metal deployments. Virtualization hosts. KVM hypervisors. OpenStack infrastructure.

Development: RHEL dev environment without cost. Testing before RHEL deployment. CI/CD runners. Build servers.

Legacy Applications: Long-term stable platform. Enterprise software compatibility. Oracle, SAP environments. Regulated industries.

Scientific Computing: Research clusters. HPC environments. Reproducible environments. Long experiment cycles.

cPanel Hosting: Primary cPanel OS (historically). Shared hosting servers. Reseller environments. Web hosting industry standard.

CentOS Administration

Common Administration Tasks

# Package management (CentOS 7 - yum)
sudo yum update -y
sudo yum install httpd php mysql-server
sudo yum remove package-name
sudo yum clean all

# Package management (CentOS 8 - dnf)
sudo dnf update -y
sudo dnf install nginx
sudo dnf module enable php:8.0

# Service management
sudo systemctl start httpd
sudo systemctl enable httpd
sudo systemctl status httpd

# Firewall (firewalld)
sudo firewall-cmd --permanent --add-service=http
sudo firewall-cmd --permanent --add-service=https
sudo firewall-cmd --permanent --add-port=8080/tcp
sudo firewall-cmd --reload
sudo firewall-cmd --list-all

# SELinux
getenforce
sudo setenforce 0  # Permissive (temporary)
sudo setsebool -P httpd_can_network_connect 1

# User management
sudo useradd -m deploy
sudo passwd deploy
sudo usermod -aG wheel deploy

# Migration to AlmaLinux/Rocky
# AlmaLinux: curl -O https://almalinux.org/almalinux-deploy.sh
# Rocky: curl -O https://rocky.page/migrate2rocky

CentOS Benefits & Migration

RHEL Compatibility: Binary-compatible with Red Hat. Enterprise software support. Vendor certifications transfer. Known behavior.

Stability: Conservative update policy. Tested packages. Minimal breaking changes. Production reliability.

Security: SELinux enabled by default. Regular security patches. CVE response. Enterprise-grade hardening.

Long Support: 10-year major version lifecycle. Extended security updates. Predictable EOL dates. Migration planning time.

Migration Options (Post-CentOS)

Rocky Linux: Founded by CentOS creator. 1:1 RHEL compatibility. Community-driven. Growing adoption.

AlmaLinux: CloudLinux-backed successor. Binary compatible. Enterprise support available. Smooth migration.

Oracle Linux: Oracle's RHEL derivative. Ksplice for zero-downtime patches. Free to use. Enterprise support optional.