Initially, all went well and I managed to make a VPN connection and surf the web. I had a small issue the other day which required me to reboot the box. Now, I can make a VPN connection, but no outbound traffic is getting out.
IPTables looks like this:
-A INPUT -p tcp -m tcp -i eth0 --dport 1723 -j ACCEPT
# PPTP Gre
-A INPUT -p gre -i eth0 -j ACCEPT
-A FORWARD -i eth0 -o ppp+ -j ACCEPT
-A FORWARD -i ppp+ -o eth0 -j ACCEPT