Computer users who still primarily work in networks require that the access to their data and resources in general is granted only to those that they allow to - just as in the case of physical property, the users of computer systems want the so-called computer security. The Internet, as the best known computer network, connects millions of people around the world granting them access primarily to a large amount of information and its users need to have the necessary means in order to achieve a given level of security. Systems for detecting intrusion in a computer system (IDS-instrusion detection system), solve the problem of unwanted network access. There are open-source and closed-commercial code IDS and it is important to have an insight into their advantages and disadvantages.Korisnici računara, koji danas pre svega rade u mrežama, imaju zahtev da pristup njihovim podacima i resursima uopšte imaju samo oni kojima se pristup dozvoli - analogno sigurnosti fizičke imovine, korisnici računarskih sistema žele takozvanu računarsku sigurnost. Internet, kao najpoznatija računarska mreža, povezuje milione ljudi širom sveta, obezbeđujući im pristup pre svega velikoj količini informacija, i korisnicima su potrebna sredstva sposobna da ostvare zadati stepen sigurnosti. Sistemi za detekciju upada u računarski sistem (IDS - intrusion detection system) rešavaju problem eliminacije neželjenih pristupa mreži. Postoje IDS otvorenog i zatvorenog - komercijalnog koda i važno je imati uvid u njihove prednosti i mane
