U radu su opisani i testirani alati otvorenog koda besplatne Linux distribucije namijenjeni administraciji mrežnih i računalnih sustava, njihovoj zaštiti te uočavanju i sprečavanju zlonamjernih napada. Nakon instalacije, implementacije OSSIM – a (Open Source Security Information Management) i njegovog konfiguriranja testirani su sljedeći alati : otkrivanje upada u sustav na temelju prepoznavanja uzoraka, otkrivanje anomalija u radu sustava te nadzor rada i performansi sustava. Svaki od alata je analiziran, opisan i testiran u računalnoj internetskoj mreži. Tijekom testiranja utvrđeno je da je OSSIM alat uspješno prepoznao lažne napade na testiranu mrežu, zabilježio ih u dnevnik zapisa te alarmirao administratora o pokušaju upada u mrežu i samim time pokazao svoju učinkovitost.

In this text is the description and result of tests of open source free Linux distribution tool which it's primary objective is to administrate, to protect and to detect intrusion of both the computer and network system. After software installation, implementation and finally the configuration of Open Source Security Information Management (OSSIM) next tools have been tested : intrusion detection based on pattern recognition, system anomalies detection and system performance supervision. Each tool has been analysed, described and tested in the computer network. During the test it was confirmed that OSSIM tool has successfully recognized false attacks on the tested network, noted them in the log diary and succesfully alarmed network administrator and thus demonstrated its effectiveness.