You can define your home and external nets. Home nets are being ignored while external nets are being processed.
var HOME_NET [10.1.1.0/24,192.168.1.0/24]
you can easily extend this lists.
Afer you have defined your sensible and home nets, you can exclude rules you don't use or don't need to monitor.
# include $RULE_PATH/ftp.rules
Just uncomment the rules you don't need.