Staying on the subject "what can I download for free". If you have an old pc lying around you could use SmoothWall Express software. It's free @ smoothwall.org.
Minimum requirements i486SX, 32 MB Ram, 512MB HDD.
Recommended Pentium (or compatible) or higher, 64MB Ram, 1GB HDD.
"SmoothWall Express is an open source firewall distribution based on the GNU/Linux operating system. Linux is the ideal choice for security systems; it is well proven, secure, highly configurable and freely††† available as open source code. SmoothWall includes a hardened subset of the GNU/Linux operating system, so there is no separate OS to install. Designed for ease of use, SmoothWall is configured via a web-based GUI, and requires absolutely no knowledge of Linux to install or use.
††† Free as in beer, libre, freedom. There is a lengthier explanation of "free software" on the GNU website "
Hope this helps.
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