Abstract: An access control system for a network manager system provided with a plurality of building blocks (BBs), each specialized for executing a plurality of functions on a plurality of resources of the network, and with a graphical user interface (GUI). Each BB comprises a database for storing access control data pertinent to said component including all resources accessible to the BB, all functions executable by the BB and all users that have the right to use the BB, according to privileges allocated to each user. The BB also comprises an access control library for writing and reading the access control data to and from the database for execution of a network operation according to the respective privileges. The access control system further comprises an access control user interface connected to the access control library of each BB, for viewing and editing the access control data on the GUI.