Theoretical part of this thesis is dedicated to describing basic terms of network communication. Usage of network communication has become a necessity and is used on daily basis for a number of purposes, starting with communication between people, going across internet shopping and banking all the way to remote controlling industrial machinery. Another theoretically described topic is how attackers abuse attributes and shortcomings of communication protocols in order to commit illegal activities, specifically denial of service type of attacks. Finally, theoretical part includes a list of found open source applications capable of launching such attacks. Practical part describes development of application, capable of launching two selected fo...