Install mod-security for apache2
apt-get install libxml2 libxml2-dev libxml2-utils libaprutil1 libaprutil1-dev sudo apt-get install libapache2-mod-security2 emacs /etc/modsecurity/modsecurity.conf
and change to following:
grep -i SecRuleEngine /etc/modsecurity/modsecurity.conf SecRuleEngine On
Restart apache2:
service apache2 restart