If you want to to backup from/to an ssh server and this server does not run on 22 as port, you can use this workaround:
rsync -r [strong]-e 'ssh -p 4321'[/strong] [email protected]:/home/user/test backup -v
This will sync from the host
[email protected] (by using ssh and port 4321) the folder /home/user/test to the folder backup on your local harddisk.
