This article presents a virtual course with the topic network security. The course has been produced by Arcada Polytechnic as a part of the production team Computer Networks, Telecommunication and Telecommunication Systems in the Finnish Virtual Polytechnic. The article begins with an introduction to the evolution of the information security requirements, the different areas and uses for cryptography and to the need of an active network security administration. The structure of the Finnish educational system is presented together with the strategy, goals and structure of the Finnish Virtual Polytechnic. The course development process is described in detail together with the software tools used to produce the course material. The contents in each chapter of the virtual course are also presented in this article. The seven course chapters are: Introduction, Network Security Administration, Antivirus Protection, Firewalls, Cryptography and Network Security, Network Security Software and Security of Wireless and Mobile Networks. All animations and exercises are described in their context. The didactical approach of the virtual course is a guided excursion to which students enroll. The task sets, consisting of exercises and study directives, that the course teacher assigns each week to the students are introduced and explained in detail. The concept of step-by-step skill assimilation, which lies behind the student guidance process, is outlined together with descriptions of the different user skill levels. The background to the graphical design of the learning platform is illustrated and motivated. Both the communicating dimension, "the interface", and the esthetical dimension, the layout, of the course graphical design are explained and analyzed in depth. The IT infrastructure needed to implement and use the learning platform of the course is described and assessed. Issues like how the students are registered and authenticated to the course are presented together with the tools for communication and interaction between student and teacher. General IT requirements together with specific both server (course provider) and client (student) side IT requirements are presented. Teaching and learning experiences, gathered from assessment forms and interviews, are presented. General experiences and experiences from doing and supervising exercises during a test course held in spring 2003 are presented both from student and teacher perspective. Changes made on the course contents after the test course are presented together with planned future development of the course. Production of a virtual course has proved to be a demanding task where experts, like graphical designers, have to be included in the production team. Important issues in producing a virtual course are the proper choice of computer software and IT technology and a sufficient and realistic budget. (Contains 11 figures.)