Comece com abaixo link
Novo filtro em /etc/fail2ban/nginx-dos.conf:
# Fail2Ban configuration file
#
# Generated on Fri Jun 08 12:09:15 EST 2012 by BeezNest
#
# Author: Yannick Warnir
#
# $Revision: 1 $
#
[Definition]
# Option: failregex
# Notes.: Regexp to catch a generic call from an IP address.
# Values: TEXT
#
failregex = ^<HOST> -.*"(GET|POST).*HTTP.*"$
# Option: ignoreregex
# Notes.: regex to ignore. If this regex matches, the line is ignored.
# Values: TEXT
#
ignoreregex =
Em nossa jail.local, temos (no final do arquivo):
[nginx-dos]
# Based on apache-badbots but a simple IP check (any IP requesting more than
# 240 pages in 60 seconds, or 4p/s average, is suspicious)
# Block for two full days.
# @author Yannick Warnier
enabled = true
port = http,8090
filter = nginx-dos
logpath = /var/log/nginx/*-access.log
findtime = 60
bantime = 172800
maxretry = 240
É claro que, no caso de você estar registrando todos os recursos do seu site (imagens, css, js, etc), seria muito fácil chegar a esses números como um usuário normal. Para evitar isso, use a diretiva access_log off do Nginx, assim:
# Serve static files directly
location ~* \.(png|jpe?g|gif|ico)$ {
expires 1y;
access_log off;
try_files $uri $uri/ @rewrite;
gzip off;
}
location ~* \.(mp3)$ {
expires 1y;
access_log off;
gzip off;
}
location ~* \.(css)$ {
expires 1d;
access_log off;
}
location ~* \.(js)$ {
expires 1h;
access_log off;
}