The FTP protocol has support for this: $ /usr/bin/ftp ftp> help Commands may be abbreviated. Commands are: ...proxy... While I've never been

The FTP protocol has support for this: $ /usr/bin/ftp ftp> help Commands may be abbreviated. Commands are: ...proxy... While I've never been able to make that work correctly, it supposedly allows transfers between two remote hosts (all cleartext of course). The logins work, but the gets and puts don't. It didn't seem worth the time to set up, and similar functionality has been added to SSH file transfer. The SITE command can also run arbitrary programs on the server (becoming something like an rsh), which will never be added to SFTP. I've actually written a couple web applications that drive a VAX with "site spawn" and some DCL.