Debian:
1. Install ipset & ipset module
$ apt-get install ipset ipset-source
$ module-assistent auto-install ipset

2. Short circuit ip-up
$ cat <<EOF > /etc/ppp/ip-up.local
#!/bin/bash
EOF
$ chmod 0755 /etc/ppp/ip-up.local

3. For shorewall change these in /etc/shorewall/shorewall.conf
IP_FORWARDING=On
FORWARD_CLEAR_MARK=No
