Q:

Is it possible to upload setuid-set file to ftp-accessible directories?

Just curious, is it possible to upload files set with setuid permission to directories using ftp and retain its setuid permission?
Or does FTP always change the permission?

A:

The FTP Specification doesn't provide a way to transmit file permission bits between systems. Which makes sense: FTP clients and servers run on a lot of different OSs with very different file permission semantics.
File permissions of uploaded files are part of the server's configuration.

