User Mode Linux is a virtual machine running on a GNULinux operating system. It is the right choice for teaching operating systems’ administration, as it does not need any dedicated hardware. It runs at user level (no need for root, i.e. administrator, access or possible security threats) and it does not have the performance problems of an emulator. This paper describes how to set up a laboratory for teaching operating systems’ administration. Categories and Subject Descriptors D.4.0 [Operating Systems]: General; D.4.6 [Operating Systems]: Security and ProtectionAccess controls; D.4.3 [Operating Systems]: File Systems Management; D.4.4 [Operating Systems]: Communications ManagementNetwork communication General Terms Experimentation, Performance, Security Keywords Teaching, Operating Systems, Administration, Virtual Machine, Security, Laboratory