I'm still unclear on some things.
1. What is meant by "stock kernel"? Is it the default kernel which came with the device?
Then, does it work for basic IPTables commands? (someone please verify this for me , because I don't have a N900 with me at the moment)

2. If it doesn't, then does one of the packages here:
http://maemo.org/packages/view/iptables/
modifies the kernel or do I have to modify the kernel before installing the package? Which package can I use for N900?

Once again, thank you in advance.