Secure Apache Web Server: A Comprehensive Guide for System Administrators

A collection of example configurations and scripts to aid system administrators in hardening Apache web servers.

Apache, out of the box, is surprisingly insecure. Many best practices and security configurations have to be configured manually before rolling Apache out in a production environment. You may use this GitHub repository as a starting point towards securing your Apache instances.

Installing ModSecurity with OWASP Core Rule Set

Step 1: Update Repositories

On Ubuntu/ Debian:

sudo apt-get update -y

On CentOS/RHEL:

sudo yum update -y

Step 2: Installing ModSecurity for Apache

On Ubuntu/ Debian:

sudo apt-get install -y libapache2-modsecurity
sudo systemctl restart apache2

On CentOS/RHEL:

sudo yum install -y mod_security
sudo systemctl restart httpd.service

Step 3: Configure ModSecurity

ModSecurity by default is only configured to log events from the default rules. We’ll have to edit the configuration file to modify the rules to detect and block malicious traffic.

Copy and rename the file:

sudo cp /etc/modsecurity/modsecurity.conf-recommended /etc/modsecurity/modsecurity.conf

Change the ModSecurity detection mode by editing the configuration file:

sudo nano /etc/modsecurity/modsecurity.conf

Change “DetectionOnly” to “On”

SecRuleEngine DetectionOnly

SecRuleEngine On

If you’re using nano you may hit CTRL+X, then Y and Enter to save and exit.

Restart Apache

On Ubuntu\ Debian:

sudo systemctl restart apache2

On CentOS\ RHEL:

sudo systemctl restart httpd.service

Step 4: Downloading and Installing OWASP ModSecurity Core Rule Set

cd /apache/conf
wget https://github.com/coreruleset/coreruleset/archive/v3.3.0.tar.gz
tar -xvzf v3.3.0.tar.gz
sudo ln -s coreruleset-3.3.0 /apache/conf/crs
cp crs/crs-setup.conf.example crs/crs-setup.conf
rm v3.3.0.tar.gz

Restart Apache

On Ubuntu\ Debian:

sudo systemctl restart apache2

On CentOS\ RHEL:

sudo systemctl restart httpd.service

Step 5: Additional Reading Material

Additional installation instructions:

Install OWASP ModSecurity Core Rule Set

Install ModSecurity

SSL Certificates

Self Signed

Following the instructions from Digital Ocean

For this tutorial, I’m assuming you’re going to be using the example.com.conf file from the repository.

Step 1: Create the SSL certificate

sudo openssl req -x509 -nodes -days 365 -newkey rsa:4096 -keyout /etc/ssl/private/apache-selfsigned.key -out /etc/ssl/certs/apache-selfsigned.crt

Fill out the prompts appropriately. The most important line is the one that requests the Common Name (e.g. server FQDN or YOUR name). You need to enter the domain name associated with your server or, more likely, your server’s public IP address. If using for the IP access only certificate in the example.com.conf please use “NA” for all values where posible.

Perfect Forward Secrecy Configuration

sudo openssl dhparam -out /etc/ssl/certs/dhparam.pem 4096

Automate with LetsEncrypt and Certbot

Following the tutorial from Certbot

Step 1: Install Certbot

sudo apt-get update -y
sudo apt-get install software-properties-common
sudo add-apt-repository universe
sudo add-apt-repository ppa:certbot/certbot
sudo apt-get update
sudo apt-get install -y certbot python3-certbot-apache