Hello,

The first line of defense in any computer security is a firewall. Many routers have built-in firewalls, but aren't as configurable as software firewalls. So if you have a gateway computer (a computer that all the data to internet has to pass through), make sure you install firewall software on it. If you've got a router as your internet gateway, make sure the firewall is enabled.

You should also note that FTP is considered very insecure because its authentication is plain-text, meaning that hackers could potentially see the password being typed and steal it. (This is not a problem for public FTP.) A safer alternative is SFTP, which operates on the SSH protocol. It's encrypted with private and public keys, so I would suggest you look into that if you're worried about FTP security.

Lastly, make sure that you keep all your software updated with the latest bug fixes and patches, as many hackers gain access to a system by exploiting security glitches in software. And make sure you check your logs, so you'll know when a hacker does break in!