My main dedicated server has multiple IPs and I wanted to assign different DNS entries to each service e.g. ftp.example.com. However when I first installed ProFTPD it was listening on my eth0 which also has the ssh, http, mail, et. al. services. So if I give out ftp.example.com then they can just guess the port of those other services. Which is why I’m giving each of them different IP addresses and different DNS entries so that ftp.example.com isn’t on the same IP as mail.example.com, making it a bit harder for someone to snoop around.
