To enable PPPoO in freebsd, your /etc/ppp/ppp.conf should look like this:
default:
set log Phase tun command
set ifaddr 10.0.0.1/0 10.0.0.2/0
internet:
set device PPPoE:INTERFACE
set authname USERNAME
set authkey PASSWORD
set dial
set login
add default HISADDR
Now "ppp -ddial internet" will connect you to the internet, there must be no default route prior to this.
If you want to setup the machine to connect to the internet on bootup, insert the following in /etc/rc.conf , 'ppp_nat="YES"' make freebsd share the internet connection.
ppp_enable="YES"
ppp_mode="ddial"
ppp_nat="YES"
ppp_profile="internet"