Tunnel setup: what happens when my IPv4 address changes?

[Pierre Abbat]

I came home and found the power off. It came back on a short while later, and I 
spent about two hours fixing the mess. I intended to reboot zyxomma (my new 
firewall) to see if I got its configuration right. After much fiddling, I got it 
to come up right when rebooted. Here are the relevant lines of rc.conf:

gif_interfaces="gif0"
ifconfig_em0="DHCP"
ifconfig_em1="inet 192.168.7.2 netmask 255.255.255.0"
ifconfig_em1_alias0="inet6 2001:470:8:42::2 prefixlen 64"
#gifconfig_gif0="69.132.98.107 216.66.22.2"
gifconfig_gif0="75.176.114.192 216.66.22.2"
ifconfig_gif0="inet6 2001:470:7:42::2 2001:470:7:42::1 prefixlen 128"

The problem is that the first address in the gifconfig statement has to be 
whatever address em0 gets from DHCP. The commented-out address is the one the 
old router got. How do I write this line so that it works even if I get a 
different address? (Telling Tunnelbroker the new address is a different problem; 
there are instructions on tunnelbroker.net.) The command that netif runs is 
"ifconfig gif0 tunnel 75.176.114.192 216.66.22.2".

Pierre
-- 
The Black Garden on the Mountain is not on the Black Mountain.