Listing 4: Firewall rules for FTP

# Add input rule for Internet -> me for FTP data connection (masqueraded)
ipfwadm -I -a accept -P tcp -S 0.0.0.0/0 20 -D 194.109.13.150 1024:65535

# Add output rules for FTP data connection
ipfwadm -O -a accept -P tcp -S 0.0.0.0/0 20 -D 193.78.174.34 1024:65535
ipfwadm -O -a accept -P tcp -S 0.0.0.0/0 20 -D 193.78.174.35 1024:65535

The first rule specifies the incoming packets on the Internet interface
of the firewall. The other rules specify the  outgoing packets to the
hosts on the local net. Remember that these packets are forwarded
through the firewall  using the (masquerading) firewall rules.