Its firmware is officially user-upgradable, since it is a Linux-based computer, as opposed to third-party "patching" of alternate receivers. All units support Dream's own DreamCrypt conditional access (CA) system, with software-emulated CA Modules (CAMs) available for many alternate CA systems. The built-in Ethernet interface allows networked computers to access the recordings on the internal hard disks on some Dreambox models. It also enables the receiver to store digital copies of DVB MPEG transport streams on Network file systems or broadcast the streams as IPTV to VideoLAN and XBMC Media Center clients. Unlike many PC based PVR systems that use free-to-air type of DVB receiver cards, the built-in conditional access allows receiving and storing encrypted content.