Learn how to configure mod_evasive for Apache with this step-by-step guide. Protect your web server from DoS, DDoS, and brute-force attacks by setting up mod_evasive effectively. #centlinux #linux #cybersecurity
Table of Contents
What is mod_evasive?
mod_evasive is an Apache HTTP Server module designed to provide evasive action against HTTP DoS (Denial of Service), DDoS (Distributed Denial of Service), and brute-force attacks. It helps protect your web server by detecting and responding to excessive requests from a single IP address, which might indicate an attack. Here are some key features and benefits of mod_evasive:
- Detection: Monitors incoming requests and identifies patterns that may indicate a DoS or DDoS attack.
- Throttling: Limits the number of requests a single IP address can make to the server within a specific time frame.
- Blocking: Temporarily blocks IP addresses that exceed the request threshold, preventing them from overwhelming the server.
- Logging: Logs suspicious activities and blocked IP addresses for further analysis and reporting.
- Alerting: Can send email alerts or trigger external commands when an attack is detected, allowing administrators to respond quickly.
- Configuration: Offers flexible configuration options to define request thresholds, block durations, and custom responses.
mod_evasive enhances the security of your Apache web server by mitigating the risk of service disruptions caused by malicious traffic, ensuring better availability and performance for legitimate users.
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How mod_evasive Works?
The module works by maintaining an internal dynamic table of IP addresses and URIs as well as denying any single IP address for any of the following conditions:
- Requesting the same page more than n times per second
- Making more than n concurrent requests on the same child per second
- Making any requests while temporarily blacklisted
If any of the above conditions are met, a 403 response is sent and the log has been generated for the IP address. Optionally, an email notification can be sent to the server owner or a system command can be run to block the IP address.
In this article, we will show you how to install and configure mod_evasive for Apache HTTP Server to defend DoS, DDoS and Brute Force attacks.
Read Also: How to install Fail2ban on CentOS 7
Linux Server Specification
we have configured a Linux machine with following specification.
| Operating System: | CentOS 7.0 |
| Web Server: | Apache 2.4.6 |
Configure mod_evasive
Check if mod_evasive is already installed.
# httpd -M | grep evasive
Syntax OK
It shows that the mod_evasive is not installed on this machine.
mod_evasive is available on EPEL (Extra Packages for Enterprise Linux) Repository, therefore we should first add EPEL repository to yum.
# wget http://download.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
--2016-04-12 19:28:58-- http://mirrors.nayatel.com/epel/6/x86_64/epel-release-6-8.noarch.rpm
Connecting to 127.0.0.1:3128... connected.
Proxy request sent, awaiting response... 200 OK
Length: 14540 (14K) [application/octet-stream]
Saving to: “epel-release-6-8.noarch.rpm”
100%[===================================================================================================================>] 14,540 –.-K/s in 0s
2016-04-12 19:28:58 (221 MB/s) – “epel-release-6-8.noarch.rpm” saved [14540/14540]
# rpm -ivh epel-release-6-8.noarch.rpm
warning: epel-release-6-8.noarch.rpm: Header V3 RSA/SHA256 Signature, key ID 0608b895: NOKEY
Preparing… ########################################### [100%]
1:epel-release ########################################### [100%]
Install mod_evasive using yum.
# yum install mod_evasive
Create log directory for mod_evasive
# mkdir -p /var/log/mod_evasive
# chown -R apache:apache /var/log/mod_evasive
mod_evasive do not required any additional configuration and it works fine with default settings. However, it is a good practice to customize the following parameters in /etc/httpd/conf.d/mod_evasive.conf according to your Server’s Traffic.
DOSEmailNotify ahmer.malik@gmail.com
DOSPageInterval 1
DOSPageCount 2
DOSSiteInterval 1
DOSSiteCount 50
DOSBlockingPeriod 60
DOSLogDir "/var/log/mod_evasive"
Restart httpd Service to apply changes.
# service httpd restart
Stopping httpd: [ OK ]
Starting httpd: [ OK ]
Test mod_evasive
Check is mod_evasive module loaded now.
# httpd -M | grep evasive
Syntax OK
evasive20_module (shared)
A Perl script is provided with mod_evasive to generate the traffic to test the configurations.
# /usr/share/doc/mod_evasive-1.10.1/test.pl
HTTP/1.1 200 OK
HTTP/1.1 200 OK
HTTP/1.1 200 OK
HTTP/1.1 200 OK
HTTP/1.1 200 OK
HTTP/1.1 200 OK
HTTP/1.1 200 OK
HTTP/1.1 200 OK
HTTP/1.1 200 OK
HTTP/1.1 200 OK
HTTP/1.1 200 OK
HTTP/1.1 200 OK
HTTP/1.1 200 OK
HTTP/1.1 200 OK
HTTP/1.1 200 OK
HTTP/1.1 200 OK
HTTP/1.1 200 OK
HTTP/1.1 200 OK
HTTP/1.1 200 OK
HTTP/1.1 200 OK
HTTP/1.1 200 OK
HTTP/1.1 200 OK
HTTP/1.1 200 OK
HTTP/1.1 200 OK
HTTP/1.1 403 Forbidden
HTTP/1.1 403 Forbidden
HTTP/1.1 403 Forbidden
HTTP/1.1 403 Forbidden
HTTP/1.1 403 Forbidden
HTTP/1.1 403 Forbidden
HTTP/1.1 403 Forbidden
HTTP/1.1 403 Forbidden
HTTP/1.1 403 Forbidden
From the output, it is clear that the mod_evasive is blocking connections. You may play around with mod_evasive parameters to optimize it according to your Server Traffic.
mod_evasive has been configured and it is defending against DoS, DDoS and Brute Force attacks.
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Final Thoughts
Configuring mod_evasive for Apache is a vital step to protect your web server from DoS, DDoS, and brute-force attacks. By following this guide, you can set up mod_evasive effectively to enhance your server’s security and ensure reliable performance.
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