Computers normally run an operating system installed on their hard drives, whether it’s Windows, OS X, or Linux. But usb access control they can also boot from removable media devices, allowing you to boot a Linux desktop from a USB drive or CD.
Use and maintain security software, and keep all software up to date – Use a firewall, anti-virus software, and anti-spyware software to make your computer less vulnerable to attacks, and make sure to keep the virus definitions current (see Understanding usb protect Firewalls , Understanding Anti-Virus Software , and Recognizing and Avoiding Spyware for more information). Also, keep the software on your computer up to date by applying any necessary patches (see Understanding Patches for more information).
So, how do we eliminate (or reduce) those risks while avoiding all kinds of complexity in design, installation, etc. The absolute simplest strategy is to put OpenBSD on a simple embedded board. Connect both computers to it with serial ports. Configure OpenBSD’s firewall correctly. On trusted system, use OpenBSD, usb secure Linux with SELinux/SMACK, FreeBSD with Capsicum, or Solaris with Trusted Extensions. The point is you want an OS on the trusted machine that’s open, has resonable protections, has been source audited for years, fixes problems, has simple app isolation method, and has online guides for about everything.