Linux behind Trendnet

[phma]

I'm running Ubuntu behind a Trendnet TEW-432BRP router. I haven't found anything in the router's web pages about protocol 41. I have some ports forwarded to the Linux box. I ran these commands:

ifconfig sit0 up
ifconfig sit0 inet6 tunnel ::216.66.22.2
ifconfig sit1 up
ifconfig sit1 inet6 add 2001:470:7:42::2/64
ifconfig

The result was a dead tunnel. When I tried to access tunnelbroker.net, the browser timed out. I turned sit1 off and the site came up again (in ipv4). Do I have to do something to the router? I also have the 6tunnel package installed.