Firewall - why not just block everything not to/from me?

Hello, I'll admit that networking isn't my strongest side, but I hope to learn some more, and this has been bugging me a little, so I hope someone will bear over with me and explain this. I have a firewall setup based on the "simple" setup in rc.firewall. I was wondering why the blocks for RFC1918

How to set up a gateway?

Hello, I have a machine running FreeBSD 4.5 STABLE. This machine has two NICs in it, one connected to the internal LAN and one connected to a ADSL modem (I'm using PPPoE). I've successfully managed to set them up so that the FreeBSD machine has access to the Internet, that works flawlessly, but