pfSense is a powerful Open Source firewall software that runs on embedded appliances on a CompactFlash card. This configuration means the firewall has no moving parts such as hard drives or fans. At times, it may be necessary to install a new CompactFlash card in the firewall or you may need to remove the existing card in order to install a new version of pfSense. Note that all versions of pfSense since the final version of 1.2.3 can be upgraded while the firewall is running without this procedure. Earlier versions will need to be upgraded by removing the card and replacing it with a new card that has the latest version and the settings downloaded for your firewall.
The following video shows the procedure to replace the CompactFlash card in a Three Port Alix Geode system. The process is similar in the larger Soekris installations that have 4-8 Ports.