What is a good free Linux FTP backup solution?

Question

I have the need for a backup solution that will let me run local incremental backups and then synchronize the backup with a remote folder over FTP. I have found several solutions that would allow me to do something like this but requires that my remote connection use SSH, rsync, or SFTP. Unfortunately, FTP is my ONLY option as the remote drive is a NAS drive with only FTP capabilities. Is there some sort of utility available, or a script I could write that would do the following:

1. Determine the files that have changed since the last backup
2. Zip then encrypt the target file
3. Copy the encrypted files to the local backup folder
4. Synchronize the backup files with the remote FTP folder

Any help is appreciated,

Mike

Answer 1

Check out duplicity:

http://duplicity.nongnu.org/index.html

It supports all 4 of your criteria.

Answer 2

Here is a solution that replaces the FTP server with a friend (or paid server):

http://crashplan.com

http://support.crashplan.com/doku.php/how_to/configure_a_headless_client (For backing up VPS servers)

It is also much easier to use if you need a restore.