I just found out I have all incoming ports open on my gprs link. Great love it etc... But I'd like a set of some sane firewall rules.

I know how to set it up but I'm not sure what ports would be good to close open etc...

This is how I want the config:

applies to gprs0 only
all outgoing ports open
all incoming ports blacked by default and exceptions for things that might need it...

If nothing needs it then I guess I only need the ssh port open.

Been ages since I did any iptables(I run openbsd where I need a firewall) so I'm asking if anyone has any ideas. It doesn't need to be elaborate like shorewall or something. Just a simple list of commands.

Thanks