Linksys Router Firewall Configuration

[ajax288]

Hi all..

I just bought a 4 port linksys cable/dsl router and I can't find a way to set the firewall function like I want.

Before that i used the ZoneAlarm software to prevent unwanted port to communicate with the internet. I looked in the setting panels of the router and the only thing I can do is to set ranges of blocked ports. So for example if i want to have port 21, 80 and 7000 openned i would have to set the fields like that:

BLOCKED PORTS:

field 1: 1 TO 20
field 2: 22 TO 79
field 3: 81 TO 6999
field 4: 7001 TO the end

There's like 5 fields in which I can specify unwanted ports but it's not enough since I have about 10 ports that must remain open.

So, is there a way to specify every ports i want to be open so those not specified are automatically closed?

Thanks for your help