How do I ban an IP address in guestbook?

There are two ways to ban an IP address from your guestbook:
 

1. OPTION:
   
   When deleting a comment from the guestbook, check the "Ban IP address" option.
    
    
2. OPTION:
   
   You can manually ban an IP address by adding IP% to the banned_ip.txt file.
   
   For example to ban IP address: 123.123.123.123
   
   Add this to the banned_ip.txt file: 123.123.123.123%
   
   You don't have to put it in a new line, IPs can be listed like this:
   123.123.123.123%321.321.321.321%111.111.111.111%