Do you know, while using TCP-Wrappers to control a service. You can tell the config files (/etc/hosts.allow or /etc/hosts.deny) to take the IP’s from a file instead of mentioning there.
Can be very useful if you have got a large number of IP’s
Consider this example:
Edit – /etc/hosts.allow
–save and exit
Now create a file /etc/myftp.hosts and mention the IP’s allowed, there in the file.
Edit – /etc/myftp.hosts
Here is a small illustration from my machine.