CentOS · Rocky Linux · AlmaLinux · Security

CentOS security for
the post-CentOS era

CentOS 7 reached end of life on June 30, 2024 — no more security patches, ever. Rocky Linux and AlmaLinux are the migration targets. Defensia protects all three, automatically handling the differences between EL7, EL8, and EL9.

Protect your EL server now →

CentOS 7 is dead. Your server isn't.

CentOS 7 reached end of life on June 30, 2024. That means zero security patches, zero bug fixes, and zero CVE responses from upstream. Yet millions of CentOS 7 servers remain online — running production workloads, exposed to the internet, accumulating unpatched vulnerabilities every day.

THE CENTOS 7 EOL PROBLEM

June 30, 2024 — CentOS 7 end of life. No more security patches from Red Hat.

CentOS Stream is not a replacement — it is a rolling release, midstream between Fedora and RHEL. Not suitable for production.

Every unpatched CVE on CentOS 7 is now permanent. OpenSSH, glibc, kernel — all frozen in time.

If you cannot migrate yet, you still need active security monitoring. That is what Defensia does.

EOL
CentOS 7 since June 2024
No security patches, no CVE fixes
Millions
of CentOS 7 servers still online
Running production workloads unpatched
30s
to install Defensia on CentOS 7
Active protection while you plan migration

Rocky Linux & AlmaLinux: the migration targets

When CentOS shifted to CentOS Stream, two community projects emerged to fill the gap. Both are enterprise-grade, both are free, and both are fully supported by Defensia.

Rocky Linux

Founded by Gregory Kurtzer, the original CentOS co-founder. Binary compatible with RHEL. Current versions: 9.7 and 10. Backed by CIQ and a large community. The spiritual successor to CentOS.

rockylinux.org

AlmaLinux

Maintained by the AlmaLinux OS Foundation (501c6 nonprofit), funded by $1M/year from CloudLinux. ABI-compatible with RHEL (not byte-for-byte). Current versions: 9.7 and 10.0. Includes the ELevate tool for in-place migration from CentOS 7.

almalinux.org

Both distributions receive timely security patches from upstream RHEL. Both use dnf for package management, firewalld with nftables, SELinux enforcing by default, and journald for system logs. Defensia works identically on both.

EL7 vs EL8/EL9: what Defensia handles differently

The jump from EL7 to EL8/EL9 changed how servers log, manage packages, and handle firewalls. Defensia auto-detects all of this at install time.

ComponentEL7 (CentOS 7)EL8/EL9 (Rocky/Alma)Defensia
SSH log location/var/log/securejournald (no file)Auto-detects both
Package manageryumdnfReads rpm database
Firewalliptables (direct)firewalld + nftablesUses ipset (works with both)
SELinuxEnforcingEnforcingCompatible (different layer)
Init systemsystemdsystemdsystemd service unit
Default PythonPython 2.7Python 3.9+No Python needed (Go binary)

On EL8/EL9, /var/log/secure does not exist by default — SSH logs go to journald. Defensia's agent uses journalctl -f as a fallback when the log file is missing, so it works on both old and new systems without any configuration.

Manual hardening vs Defensia

Every RHEL hardening guide lists the same steps. Here is what each covers and what Defensia automates with a single install command.

Security stepManual (EL guide)Defensia
Configure firewalld rulesfirewall-cmd + zonesAdds intelligent blocking on top
Block SSH brute forceyum/dnf install fail2ban + config
Auto security updatesyum-cron or dnf-automaticCVE scanning + alerts
Detect web exploits (WAF)ModSecurity + OWASP CRS
Scan for malwareyum install clamav + cron
File integrity monitoringaide --init + cron
Rootkit detectionrkhunter --check
Audit system activityauditd rules + aureport
CIS benchmark scanningoscap + scap-security-guideSecurity posture score (0-100)
Real-time attack dashboardNot available
Multi-server managementNot available
Geoblocking by countryiptables + GeoIP database
Slack / email / Discord alertsCustom scripts

Manual hardening is essential but incomplete. firewalld blocks ports — it does not detect a bot trying 10,000 passwords on port 22. fail2ban handles SSH — it does not detect SQL injection in your nginx logs. rkhunter scans once — it does not watch for new web shells uploaded in real time. Defensia covers all of these from a single agent.

SELinux + Defensia

SELinux is enabled and enforcing by default on CentOS, Rocky Linux, and AlmaLinux. It provides Mandatory Access Control (MAC) — confining processes to only the resources they need. Defensia operates at a completely different layer.

SELinux

Mandatory Access Control. Confines processes: Apache can only access its document root, SSH can only read its authorized_keys. Prevents privilege escalation after a breach. Does not detect or block incoming attacks.

Defensia

Network IDS + WAF. Monitors SSH logs and web server access logs. Detects brute force, SQL injection, XSS, path traversal. Blocks attacker IPs via ipset before they can exploit anything SELinux would need to contain.

Keep SELinux enforcing. Install Defensia on top. SELinux contains damage after a breach; Defensia prevents the breach from happening. Different layers, maximum protection together.

Install Defensia on CentOS, Rocky, or AlmaLinux

Same command. Works on EL7, EL8, and EL9. Auto-detects everything.

$ curl -fsSL https://defensia.cloud/install.sh | sudo bash

# What happens on EL systems:

1. Downloads the Go binary (~15MB) for your architecture (amd64 or arm64)

2. Installs to /usr/local/bin/defensia-agent

3. Creates a systemd service unit

4. Auto-detects /var/log/secure (EL7) or journald (EL8/EL9)

5. Auto-detects nginx/Apache/httpd access logs if present

6. Starts protecting immediately — no config files to edit

The agent is a single Go binary with zero dependencies. It does not require Python, Ruby, or any runtime. Works alongside SELinux enforcing mode, firewalld, and any existing security tooling. The install script detects your EL version and ensures compatibility with iptables, ipset, and systemd.

What Defensia detects on EL systems

The agent reads EL-specific log paths and system data to detect attacks across every surface.

SSH attacks via /var/log/secure or journald

CentOS 7 logs SSH events to /var/log/secure. Rocky/AlmaLinux 8/9 use journald by default. Defensia auto-detects which method your system uses and monitors 15 SSH attack patterns: failed passwords, invalid users, pre-auth disconnects, PAM failures, and kex negotiation drops.

Deep dive into SSH protection →

Web application exploits

Reads nginx, Apache, and httpd access logs to detect SQL injection, XSS, path traversal, RCE, SSRF, and 10+ more OWASP attack types. Auto-detects standard EL log paths including /var/log/httpd/ and /var/log/nginx/.

See WAF detection details →

Malware & web shells

Scans the filesystem with 64,000+ hash signatures and 684 dynamic patterns. Detects PHP backdoors in upload directories, obfuscated shells, cryptominers, and suspicious executables in /tmp and /dev/shm.

CVE vulnerability scanning

Matches installed rpm packages against the NVD database with EPSS probability scores and CISA KEV urgency flags. Critical for CentOS 7 where packages will never be patched upstream.

Bot & crawler abuse

70+ bot fingerprints identified from User-Agent strings and request patterns. Legitimate bots (Googlebot, Bingbot) are allowed; vulnerability scanners and credential stuffing bots are blocked.

Docker container monitoring

If Docker is installed on your EL server, Defensia detects the Docker version, running containers, and web containers. Reads container logs for attack detection across all services.

Everything included for CentOS, Rocky & AlmaLinux

Free tier covers the essentials. Pro adds deeper security intelligence.

FREE

SSH Protection

15 patterns. Auto-reads /var/log/secure or journald.

PRO

Web Firewall (WAF)

OWASP attack detection from nginx/Apache/httpd logs.

FREE

Real-time Dashboard

Live event feed, charts, ban timeline, all servers in one view.

PRO

Malware Scanner

64K+ hash signatures. Web shells, cryptominers, rootkit checks.

PRO

CVE Intelligence

Scans rpm packages against NVD + CISA KEV + EPSS scores.

PRO

Geoblocking

Block entire countries at the firewall level. Per-server policy.

PRO

Security Score

0-100 score (A-F grade). SSH, firewall, file perms, credentials.

PRO

Bot Management

70+ bot fingerprints. Allow, log, or block per policy.

PRO

Alerts

Slack, email, Discord, and webhook notifications on attacks.

Frequently asked questions

Does Defensia work on CentOS 7?

Yes. Defensia fully supports CentOS 7 even after its end of life. The agent reads /var/log/secure for SSH attack detection, uses iptables for blocking, and scans installed rpm packages for CVEs. While CentOS 7 will never receive upstream patches, Defensia provides active protection by detecting and blocking attacks in real time.

Does Defensia support Rocky Linux?

Yes. Rocky Linux 8 and 9 are fully supported. The agent auto-detects journald for SSH log monitoring (since /var/log/secure does not exist by default on EL8/EL9), uses ipset with iptables for blocking, and reads httpd/nginx access logs for WAF detection.

Does Defensia support AlmaLinux?

Yes. AlmaLinux 8 and 9 are fully supported. The agent works identically on Rocky Linux and AlmaLinux — both are EL-based distributions with the same log paths, package manager, and firewall configuration.

How does Defensia read SSH logs on EL9?

On EL8 and EL9 systems (Rocky Linux, AlmaLinux, CentOS Stream), /var/log/secure does not exist by default. SSH authentication events go to journald instead. Defensia detects this automatically and falls back to reading SSH logs from journalctl -f. No configuration needed.

Do I still need firewalld?

Yes, keep firewalld running. firewalld handles static zone-based rules — which ports to open, which services to allow. Defensia adds dynamic, intelligent blocking on top: it detects attack patterns and blocks offending IPs via ipset. They work at different layers and complement each other. Defensia never modifies your firewalld rules.

Is Defensia free?

Yes. The free plan includes 1 server with SSH protection, the full real-time dashboard, and bot detection. The agent is MIT licensed and open source on GitHub. Pro costs EUR 9/server/month (EUR 7 billed annually) and adds WAF, malware scanning, CVE scanning, geoblocking, alerts, and team management.

Sources

CentOS 7 end-of-life date confirmed by the CentOS Project at centos.org — official EOL: June 30, 2024.

Rocky Linux information from rockylinux.org. Founded by Gregory Kurtzer, CentOS co-founder.

AlmaLinux information from almalinux.org. 501(c)(6) nonprofit, $1M/year funding from CloudLinux.

EL7/EL8/EL9 differences based on Red Hat Enterprise Linux documentation (access.redhat.com).

Attack frequency and detection data based on Defensia telemetry across production EL servers monitored from January to April 2026.

Protect your EL server now

One command. Works on CentOS 7, Rocky Linux 9, and AlmaLinux 9.

$ curl -fsSL https://defensia.cloud/install.sh | sudo bash
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