The bachelor thesis is focused on the issue of denial of service attacks. These types of attacks are still up to date, but are currently being used in their distributed form. The theoretical part of the thesis describes the basic mechanisms of attacks and the division of attacks. Also there are described the most famous type of attacks. The theoretical part also includes a description of how to respond to these attacks. Four basick methods are described (prevention, detection, identification and response), as well as intrusion detection and prevention systems (IDPS). The practical part deals with connection of intrusion detection system and router, for detection and filtration on said router