Both firewall applications do use snort. Untangle use their own custom snort rules to avoid false positives. Pfsense doesn't use snort inline so it's not as efficient or effective as an IPS.
I also want to find out if an atom 1.8 ghz server can handle a bulk of snort rules without...
Any distros with inline snort built into them that could run on atom mini-itx motherboards? I need something with a low carbon footprint. Excessive power use can get costly over time.
Untangle does use snort rules but it's only a small chosen set. I think it might be possible to use the VRT/ET rules for snort but you'll have to update it yourself. It won't be automatic. There are postings on the Untangle forums to discuss how to do it.
Pfsense doesn't have snort built...