A Synology NAS can be used as a FTP server out-of-the-box (after enabling it), but there is no FTP client installed that can be used from a interactive shell. You can install a FTP client, lftp by Alexander Lukyanov, using ipkg.
If you haven’t installed ipkg yet, please install it first (link).
Install package lftp
You can install the package lftp in with the command: ipkg install lftp
Disable certificate verification
By default lftp will check the ssl certificate of the destination. If no trusted certificate is found the command is not executed.
$ lftp email@example.com:/directory
cd: Fatal error: Certificate verification: Not trusted
You can disable the certificate verification in lftp by setting an option in the ~/.lftp/rc file. This file does not exist by default, nor does the .lftp directory.
- Create the .lftp directory with the command : mkdir /root/.lftp
- Create and edit the rc file with the command : vi /root/.lftp/rc
- Press ‘i’ for edit mode
- Add the line : set ssl:verify-certificate no
- Exit edit mode by pressing Escape (twice)
- Close and save the file by pressing Z (capital z) twice)