Nessus consists of two main components: a server daemon (nessusd) and a client application (nessus). Both client and server can be run on the same host, or they can be installed on separate hosts. The single-host configuration is the easier of the two to set up and use, and is the best approach for your first installation. The nessus client can be run with an X Window GUI or via the command line. The GUI version is much easier for the novice to use, and will be our focus for this article. Once you're familiar with the GUI, running Nessus from the command line will seem far less daunting.