/usr/share/octave/4.2.2/m/@ftp/ is in octave-common 4.2.2-1ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/octave/4.2.2/m/@ftp/ascii.m
/usr/share/octave/4.2.2/m/@ftp/binary.m
/usr/share/octave/4.2.2/m/@ftp/cd.m
/usr/share/octave/4.2.2/m/@ftp/close.m
/usr/share/octave/4.2.2/m/@ftp/delete.m
/usr/share/octave/4.2.2/m/@ftp/dir.m
/usr/share/octave/4.2.2/m/@ftp/display.m
/usr/share/octave/4.2.2/m/@ftp/ftp.m
/usr/share/octave/4.2.2/m/@ftp/loadobj.m
/usr/share/octave/4.2.2/m/@ftp/mget.m
/usr/share/octave/4.2.2/m/@ftp/mkdir.m
/usr/share/octave/4.2.2/m/@ftp/mput.m
/usr/share/octave/4.2.2/m/@ftp/rename.m
/usr/share/octave/4.2.2/m/@ftp/rmdir.m
/usr/share/octave/4.2.2/m/@ftp/saveobj.m