An apache module for detecting DoS attacks
C
Latest commit 47edb4d Oct 27, 2013 @stanaka Merge pull request #2 from cubicdaiya/issues/support24
support Apache2.4

README.md

mod_dosdetector

An apache module for detecting DoS attacks. When detecting DoS attacks, this module set environment variables. Note that this module itself does not affect the response.

Install

Just do make install

make install

Configuration

An sample configuration for mod_dosdetector.

LoadModule dosdetector_module modules/mod_dosdetector.so
LoadModule rewrite_module modules/mod_rewrite.so

<IfModule mod_dosdetector.c>
# enable the module
DoSDetection on
# DoSThreshold is the threshold for detecting 'soft' DoS attacks
DoSThreshold 5
# DoSHardThreshold is the threshold for detecting 'hard' DoS attacks
DoSHardThreshold 10
# DoSPeriod is the time window for counting requests
DoSPeriod 60
# DoSBanPeriod is the period to hold DoS state after a DoS detection
DoSBanPeriod 60
# DoSShmemName is the name of shared memory
DoSShmemName dosshm
# DoSTableSize is the table size to store ip addresses of clients
DoSTableSize 100
# Set DoSForwarded if you want to use X-Forwarded-For header for Remote Address
DoSForwarded on
# Set DoSIgnoreContentType if you want to ignore requests with some content-types
# Regular expression can be used
DoSIgnoreContentType image/*
</IfModule>

RewriteEngine on

# Redirect to some urls for requests detected as a soft DoS attack
RewriteCond  %{ENV:SuspectDoS} .+
RewriteRule .* http://example.com/ [P,L]

# Return 403 for requests detected as a hard DoS attack
RewriteCond  %{ENV:SuspectHardDoS} .+
RewriteCond %{REMOTE_ADDR} !^(192\.168\.0\.1)$
RewriteRule .* - [F,L]

RewriteLog logs/rewrite_log
RewriteLogLevel 0

Output to error logs

When a request is detected as a DoS attack, the module output following logs.

[Sun Jul 1 13:46:48 2007] [notice] dosdetector: '127.0.0.1' is suspected as DoS attack! (counter: 181)
[Sun Jul 1 13:48:23 2007] [notice] dosdetector: '127.0.0.1' is suspected as Hard DoS attack! (counter: 361)