A method of monitoring and protecting a network against attacks from a public network, particularly from the Internet, where the network includes a firewall and an attack detection system on the protected side of the firewall, which inspects data packets passing the firewall and installs protective policies at the firewall in case of detecting data packets representing an attack. Regarding high flexibility and quick adaptability to changing attack situations, the method is characterized in that the firewall is configured by the attack detection system in such a way that the attack detection system or a system co-operating with the attack detection system is provided information about data packets representing an attack.