Debian is built for stability, not security automation. No UFW, no unattended-upgrades, no default firewall rules. Defensia fills those gaps with one command — zero configuration required.
Install on Debian in 30 secondsDebian's philosophy is stability and minimalism. A fresh Debian install ships with no firewall frontend, no automatic security updates, and no intrusion detection. That's intentional — Debian trusts you to configure what you need. But on an internet-facing server, "secure by default" is not the same as "secure in practice."
Debian is the foundation of Ubuntu, but without Ubuntu's opinionated defaults. Experienced sysadmins choose Debian precisely because it doesn't add unnecessary packages. The tradeoff: you need to add your own security layer. Defensia is that layer — lightweight, automatic, and aligned with Debian's no-bloat philosophy. For a broader view of Linux server protection, see Linux server security.
Every Debian hardening guide tells you to do these steps manually. Defensia handles them automatically from the moment you install the agent.
| Hardening step | Manual on Debian | Defensia |
|---|---|---|
| Firewall rules (iptables/nftables) | Write rules manually or install UFW | ✓ |
| SSH brute force protection | Install + configure fail2ban jails | ✓ |
| Web application firewall | Install + tune ModSecurity + OWASP CRS | ✓ |
| Automatic security updates | Install + configure unattended-upgrades | CVE scanning |
| Package integrity verification | Run debsums manually | ✓ |
| Rootkit detection | Install + run rkhunter/chkrootkit | ✓ |
| Malware scanning | Install ClamAV + write custom scripts | ✓ |
| Service restart after updates | Install + configure needrestart | Monitored |
| Real-time attack dashboard | Not available | ✓ |
| Multi-server management | Not available | ✓ |
Manual hardening requires ongoing maintenance — rules drift, packages change, new CVEs appear daily. Defensia keeps everything in sync automatically. It replaces the need for fail2ban jail configuration entirely. See SSH brute force protection for details on how Defensia handles authentication attacks.
One command. Works on Debian 11 Bullseye and Debian 12 Bookworm. No extra packages, no repositories to add, no dependencies to resolve. The agent is a single Go binary — no Python, no Ruby, no PHP runtime required.
The agent uses systemd for process management and ipset + iptables for blocking — both standard on Debian. No kernel modules, no eBPF, no custom firewalls. Unlike Ubuntu, Debian uses raw iptables/nftables instead of UFW, and Defensia works with both.
The agent auto-detects Debian log locations and system tools. No configuration needed — it knows where Debian keeps everything.
15 detection patterns: failed passwords, invalid users, pre-auth disconnects, PAM failures, kex negotiation errors, max auth attempts exceeded. Reads auth.log in real time.
/var/log/auth.log15+ OWASP attack types: SQL injection, XSS, path traversal, RCE, SSRF, shellshock, XXE. Auto-detects nginx and Apache access logs including virtual hosts.
/var/log/nginx/access.log, /var/log/apache2/access.log64,000+ hash signatures and 684 dynamic detection patterns. Finds PHP backdoors in upload directories, cryptominers in /tmp, reverse shells, obfuscated code. Scans WordPress databases for injected content.
Reads installed packages from dpkg, matches against the National Vulnerability Database (NVD), scores with EPSS exploit probability, flags CISA KEV entries. Replaces manual apt-listbugs checks.
dpkg --get-selectionsDetects modified system binaries by comparing against dpkg package checksums. Finds rootkits that replace ls, ps, netstat, and other core utilities with trojanized versions.
dpkg -VFinds world-readable .env files, exposed .git directories, SSH keys with wrong permissions, and cloud credential files. Critical on Debian where AppArmor profiles may not be enforcing.
Debian maintains its own security tracker at security-tracker.debian.org, publishing DSA (Debian Security Advisory) and DLA (Debian LTS Advisory) notices. It's thorough but requires manual monitoring. Defensia automates the entire process.
| Capability | Debian Security Tracker | Defensia |
|---|---|---|
| Data source | Debian-specific DSA/DLA | NVD + EPSS + CISA KEV |
| Package matching | Manual cross-reference | Automatic via dpkg |
| Exploit probability | Not provided | EPSS score (0-1) |
| Active exploitation flag | Not provided | CISA KEV catalog |
| Delivery method | Mailing list + web page | Dashboard + alerts |
| Multi-server view | Not available | All servers in one dashboard |
| Notification channels | Email (debian-security-announce) | Email, Slack, Discord, webhook |
The Debian Security Tracker is an excellent reference, but it requires you to subscribe to debian-security-announce, cross-reference installed packages manually, and decide which CVEs actually affect your server. Defensia reads your installed packages via dpkg, matches them against the NVD, scores them with EPSS (exploit probability), and flags anything in the CISA Known Exploited Vulnerabilities catalog. No mailing lists, no manual checks.
Debian is one of the most popular base images for Docker containers (debian:bookworm-slim). Many hosting providers — OVH, Hetzner, Contabo — default to Debian for dedicated servers and VPS instances. When Debian is your Docker host, every container inherits the host's security posture.
Defensia detects Docker installations on Debian, monitors container health, reads web server logs from containerized nginx and Apache instances, and blocks attackers at the host firewall level. Whether you run Docker Compose stacks or standalone containers, the agent sees all traffic flowing through the host network. See container security for Docker and Kubernetes-specific features.
Released June 2023. Full security support until June 2026, LTS until June 2028. Ships with Linux 6.1 LTS kernel, nftables as default firewall backend.
Linux 6.1nftablesPython 3.11OpenSSH 9.2Released August 2021. Standard support ended August 2024. LTS support until August 2026. Still widely deployed on dedicated servers and legacy infrastructure.
Linux 5.10iptablesPython 3.9OpenSSH 8.4 Debian derivatives (Devuan, Kali, Raspberry Pi OS, Proxmox VE) are also compatible. Requires: systemd + iptables + root access.
Start with the basics: disable root SSH login, use key-based authentication, configure a firewall, and enable automatic security updates. Or install Defensia with one command and get SSH protection (15 patterns), WAF (15+ OWASP types), malware scanning (64K+ signatures), CVE detection, and a real-time dashboard — all without editing a single config file. Defensia handles the critical hardening steps that most Debian guides describe manually.
Yes. Defensia works on both Debian 12 Bookworm and Debian 11 Bullseye. The agent auto-detects nftables (Bookworm default) and iptables (Bullseye default) and uses the appropriate backend. It also supports Debian derivatives like Devuan, Proxmox VE, and Raspberry Pi OS.
Defensia uses ipset with iptables for IP blocking. On Debian 12 Bookworm, iptables commands are translated to nftables via the iptables-nft compatibility layer, which is installed by default. You don't need to choose or configure either — the agent handles it automatically.
Yes. Defensia detects all SSH attack patterns that fail2ban covers, plus adds WAF (15+ OWASP attack types), malware scanning (64K+ hash signatures), CVE scanning, geoblocking, bot management, and a real-time web dashboard. No jail configuration, no filter files, no regex to maintain.
Defensia reads installed packages from dpkg and matches them against the NVD (National Vulnerability Database). Each CVE is scored with EPSS (exploit probability) and flagged if it appears in the CISA Known Exploited Vulnerabilities catalog. This is more comprehensive than subscribing to debian-security-announce because it covers all packages, not just those with a DSA.
Yes. The free plan includes 1 server with full SSH protection, bot detection, and the real-time dashboard. The agent is MIT licensed and open source. Pro costs EUR 9/server/month (EUR 7 billed annually) and adds WAF, malware scanning, CVE scanning, geoblocking, alerts, and team management.
Automated protection for all Linux distributions.
15 detection patterns, ipset blocking.
Docker, Swarm, and Kubernetes native.
OWASP attack detection from server logs.
Full comparison: fail2ban vs Defensia.
Postfix & Dovecot brute force protection.
One command. Under 30 seconds. Works on Bullseye and Bookworm.
No credit card required. Free for one server.