Ciao a tutti!
Ho seguito la guida di Madman, ma all'avvio del firewall mi dà un errore:

Failed to start firewall :

Loading /usr/share/shorewall/functions...
Processing /etc/shorewall/params ...
Processing /etc/shorewall/shorewall.conf...
Loading Modules...
Starting Shorewall...
Initializing...
Shorewall has detected the following iptables/netfilter capabilities:
NAT: Available
Packet Mangling: Available
Multi-port Match: Available
Extended Multi-port Match: Available
Connection Tracking Match: Available
Packet Type Match: Available
Policy Match: Not available
Physdev Match: Available
IP range Match: Available
Recent Match: Available
Owner Match: Available
Ipset Match: Not available
ROUTE Target: Available
Extended MARK Target: Available
CONNMARK Target: Available
Connmark Match: Available
Determining Zones...
Zones: net loc
Validating interfaces file...
Validating hosts file...
Validating Policy file...
Error: Duplicate policy DROP

come poter ovviare?
Grassie !!!