You can check what ports, etc that you have open at grc.com.

>
>I've installed the free ZoneAlarm and I'm quite happy with it. I assume it's working when it says it is. For instance just this evening it has blocked 62 attempts at access. Many of these attempts came from the same URL repeatedly.
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>I don't know what it would have looked like before I got a cable modem, but I'm sure that I'm more of a target now.
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>Peter