BlackIce does block...
"BlackICE Defender
BlackICE Defender is an industrial-strength anti-hacker system that delivers unmatched protection to your PC. It scans your DSL, cable modem, or dial-up Internet connection looking for hacker activity. When it detects an attempted intrusion, it automatically blocks traffic from that source, keeping intruders from accessing your system.
The Risk Is Real"
Thats straight from NetworkIce.com, unless they are lying about their product..
