How to Use FTP to Access Files on a Mac
One way to give others access to your files is to run an FTP server on your Mac. Mac OS X Snow Leopard comes with an FTP server built in, so you just have to activate it. You might wonder why you’d use FTP to share files when you can use Personal File Sharing or Windows File Sharing. The main advantage to FTP is compatibility: Not only can people on your LAN access files, but anyone on the Internet can also access your files, regardless of the type of machine they’re using.
Just as you do with the other file-sharing methods, you need to create a user account on your computer before someone can connect to and get files from your Mac. After you have accounts created for the users, you can enable FTP sharing like this:
4Click the Share Files and Folders Using FTP check box to enable it.
Snow Leopard reminds you on the Advanced sheet that people can use ftp://<ip address>, where ip address is the IP address of your Mac.
The Advanced dialog, and System Preferences window close and your changes are saved.
If you’re using an AirPort/AirPort Extreme Base Station or other cable/digital subscriber line (DSL) router to share your Internet connection, place the Mac that you want people on the Internet to access in a DMZ, or demilitarized zone. Check your cable/DSL router documentation for more information.