Mod security

sudo apt-get update
sudo apt-get install libxml2 libxml2-dev libxml2-utils
sudo apt-get install libapache2-modsecurity
ln -sf /usr/lib/x86_64-linux-gnu/libxml2.so.2 /usr/lib/libxml2.so.2
sudo mv /etc/modsecurity/modsecurity.conf-recommended /etc/modsecurity/modsecurity.conf
cd /tmp

sudo wget https://github.com/SpiderLabs/owasp-modsecurity-crs/tarball/v2.2.5 -O modsecurity-crs_2.2.5.tar.gz

sudo tar zxf modsecurity-crs_2.2.5.tar.gz

sudo cp -R modsecurity-crs_2.2.5/* /etc/modsecurity/

sudo rm modsecurity-crs_2.2.5.tar.gz

sudo rm modsecurity-crs_2.2.5 -r

sudo mv /etc/modsecurity/modsecurity_crs_10_setup.conf.example /etc/modsecurity/modsecurity_crs_10_setup.conf  


#To enable rulesets create /etc/apache2/conf.d/modsecurity.conf file with following content:
<ifmodule mod_security2.c>
SecRuleEngine On
</ifmodule>


sudo a2enmod mod-security
sudo service apache2 restart

Fail /etc/apache2/mods-enabled/mod-security.conf

<IfModule security2_module>
        # Default Debian dir for modsecurity's persistent data
        SecDataDir /var/cache/modsecurity

        # Include all the *.conf files in /etc/modsecurity.
        # Keeping your local configuration in that directory
        # will allow for an easy upgrade of THIS file and
        # make your life easier
        Include "/etc/modsecurity/*.conf"
        Include "/etc/modsecurity/activated_rules/*.conf"
#       Include "/etc/modsecurity/optional_rules/*.conf"
        Include "/etc/modsecurity/base_rules/*.conf"
</IfModule>

https://www.owasp.org/index.php/Category:OWASP_ModSecurity_Core_Rule_Set_Project

http://blog.spiderlabs.com/2011/07/modsecurity-sql-injection-challenge-lessons-learned.html