when i activate the firewall, internet sharing stops working

im new to mac and have a few questions
1. my shared tab in the finder has some unknown computers listed, and when i select any of them, it says connected as guests. and also i can see their shared folder. anybody knows why? and when i activate my firewall, the above mentioned computers disappear. am i being hacked?

2. another problem is when i activate the firewall my internet stops working on the laptop which im sharing via airport of my imac. i dont know if my internet modem has built-in firewall, dont know how to check either.

3. how do i setup password for internet sharing?

thanks guys..

Cromulent said:

I assume you have got your firewall set to block all incomming connections. If so you are blocking your laptop from acessing your main computers internet connection.

Click to expand...

THANKS

Cromulent said:

I assume you have got your firewall set to block all incomming connections. If so you are blocking your laptop from acessing your main computers internet connection.

Click to expand...

THANKS have set the firewall to "set access for specific services.... " and the net is working.