Fail2ban
- 12 installs
- 1 repo stars
- Updated March 10, 2026
- davidcastagnetoa/skills
Configure Fail2ban to read Nginx logs and auto-ban IPs at iptables after repeated 401, 403, or 429 responses, complementing an app-level rate limiter.
About
Configures Fail2ban to parse Nginx logs and auto-ban IPs at the kernel firewall after repeated 401/403/429 errors. A developer uses it to block volumetric abuse and brute-force attempts before requests reach the app.
- Reads Nginx/FastAPI logs and bans abusive IPs via iptables/nftables
- Jail and filter configs for repeated 401/403/429 responses
Fail2ban by the numbers
- 12 all-time installs (skills.sh)
- Ranked #1,646 of 2,203 Security skills by installs in the Skillselion catalog
- Data as of Jul 29, 2026 (Skillselion catalog sync)
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| Installs | 12 |
|---|---|
| repo stars | ★ 1 |
| Last updated | March 10, 2026 |
| Repository | davidcastagnetoa/skills ↗ |
What it does
Configure Fail2ban to read Nginx logs and auto-ban IPs at iptables after repeated 401, 403, or 429 responses, complementing an app-level rate limiter.
Files
fail2ban
Fail2ban lee los logs de Nginx/FastAPI y banea automáticamente las IPs que generan demasiados errores 401, 403 o 429. Complementa al rate limiter de Redis con bans a nivel de iptables/nftables — más eficiente que rechazar en la capa de aplicación.
When to use
Instalar en los nodos donde corre Nginx. El ban a nivel de kernel (iptables) rechaza paquetes antes de que lleguen a Nginx — protección más eficiente para ataques volumétricos.
Instructions
1. Instalar: apt-get install fail2ban en el host de Nginx. 2. Crear /etc/fail2ban/jail.d/kyc-nginx.conf:
[kyc-nginx-auth]
enabled = true
port = 443
filter = kyc-nginx-auth
logpath = /var/log/nginx/access.log
maxretry = 10 # 10 intentos fallidos
findtime = 300 # en 5 minutos
bantime = 86400 # ban de 24 horas
[kyc-nginx-ratelimit]
enabled = true
port = 443
filter = kyc-nginx-ratelimit
logpath = /var/log/nginx/access.log
maxretry = 20
findtime = 60
bantime = 36003. Crear filtro /etc/fail2ban/filter.d/kyc-nginx-auth.conf:
[Definition]
failregex = ^.*"status":40[13].*"remote_addr":"<HOST>".*$4. Crear filtro para rate limiting (status 429):
[Definition]
failregex = ^.*"status":429.*"remote_addr":"<HOST>".*$5. Reiniciar: systemctl restart fail2ban. Verificar: fail2ban-client status kyc-nginx-auth. 6. Whitelist de IPs internas y de monitorización: ignoreip = 127.0.0.1/8 10.0.0.0/8.
Notes
- En Kubernetes, Fail2ban debe correr en el nodo de Nginx (DaemonSet o en el host), no como sidecar — necesita acceso a iptables del host.
- Sincronizar los bans entre nodos via
fail2ban-client+ Redis o usandoipsetcompartido. - Mantener una duración de ban progresiva: 1h en primer ban, 24h en segundo, permanente en tercero.
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