[Asterisk-Users] SIP extension outside of IP tables firewall

[Brian Weaver]

I have an Asterisk PBX on the private lan, which is protected
from the public Internet with a Linux iptables machine. The
firwall is it's own seperate box running NAT with SPI.

I want to drop a SIP phone at my brothers house, and have it be an
extension off my Asterisk box.  I've been looking around at some FAQ
info on forwarding ports, and also looked at siproxd. 

Anyway, I'm posting this, because this seems like a really "standard"
thing people would want to do with Asterisk/Iptables, so is there
a standard solution that I can apply?