In my experience Firestarter is a effective firewall and, on Linux, it starts automatically every time we boot up Ubuntu. But, when I decided to use a VPN tunnel through openvpn, I had some connection problems. In fact I was able to initialize my VPN services but, after a while, all the internet connections were mysteriously shut down.
The “problem” was Firestarter which cut off the connection as forbidden considering my inbound/outbound Policy.
To solve this matter you have to open a tunnel on Firestarter to allow VPN working:
1- open the configuration file my VPN provider gives to its users (generally its a text file containing all the configuration info used, in my case, by openvpn) and I searched for the IP address of the default starting connection used to authenticate the VPN services (e.g. 177.458.563.25). Save somewhere or memorize this VPN IP address.
2- open a Terminal and type:
3- using nautilus go to File System (it’s before home folder) and open etc–>firestarter and open the file user-pre using Gedit (or your preferred text editor)
4- the user-pre file is usually empty so don’t panic and write these lines into it:
iptables -A INPUT -j ACCEPT -s xxx.xxx.xxx.xxx -p esp iptables -A INPUT -j ACCEPT -s xxx.xxx.xxx.xxx -p udp -m multiport -sports isakmp,10000 iptables -A INPUT -j ACCEPT -i tun+ iptables -A OUTPUT -j ACCEPT -d xxx.xxx.xxx.xxx -p esp iptables -A OUTPUT -j ACCEPT -d xxx.xxx.xxx.xxx -p udp -m multiport -dports isakmp,10000 iptables -A OUTPUT -j ACCEPT -o tun+
Now you have to substitute the xxx.xxx.xxx.xxx with the VPN IP address you have found at step 1 (in my example was 177.458.563.25).
5- Save the user-pre file and close Gedit and Nautilus
6- open a new Terminal and restart Firestarter typing:
sudo /etc/init.d/firestarter restart