firewall pppoe and outside interface

[Antoine Jacoutot]

Hi !

I have a little question. I am actually trying to configure a FreeBSD firewall 
(...still learning). I am connected to DSL with pppoe and I can't decide 
which is my outside interface.
Right now, everything is open and nat is working on the tun0 interface (the 
pppoe interface).
Here is the output of ifconfig:

ed0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        ether 52:54:00:e2:77:35
vr0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        inet 192.168.0.1 netmask 0xffffff00 broadcast 192.168.0.255
        ether 00:50:ba:1e:33:e0
        media: Ethernet autoselect (100baseTX <full-duplex>)
        status: active
lp0: flags=8810<POINTOPOINT,SIMPLEX,MULTICAST> mtu 1500
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
        inet 127.0.0.1 netmask 0xff000000
ppp0: flags=8010<POINTOPOINT,MULTICAST> mtu 1500
sl0: flags=c010<POINTOPOINT,LINK2,MULTICAST> mtu 552
faith0: flags=8002<BROADCAST,MULTICAST> mtu 1500
tun0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1492
        inet xxx.xxx.xxx.xxx --> xxx.xxx.xxx.xxx netmask 0xffffffff
        Opened by PID 15147

The DSL modem is plugged into ed0 (which does not have @ip since it's pppoe, 
it doesn't need one). So should I considere my outside interface as tun0 or 
ed0 ? The natd interface is tun0, that I know.

Thanks for any hints.

Antoine