firewall setup

[Pierre Abbat]

I'm going to set up the new box as my firewall. I need it to do this:
*Get an external address through DHCP.
*Forward IPv6 packets through a he.net tunnel I have.
*Assign IPv6 addresses to the computers on the inside. I don't find the radvd 
program or package.
*Forward IPv4 packets on certain ports to certain hosts. For example, all 
incoming packets on port 80 go to 192.168.7.10.
*Run NAT on outgoing packets from inside computers. This means I have to run 
natd, but "rcrun enable natd" doesn't work.
*Give outgoing SIP packets higher priority.
*Filter incoming TCP connections on IPv6.
*Block all packets from addresses listed in a file of password guessers, which 
is updated by a cron job on the Linux box.
*Block all connections from the outside to ports 60xx (X11), including the 
ports on the firewall itself.

em0 is the currently unconnected outside interface; em1 is the inside 
interface.

How can I set all this up?

Pierre
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