Igor Sobrado writes:
> 
> Should not be ~ftp, ~ftp/bin, and ~ftp/etc unwritable by anyone
> (mode 0555) instead of 0755?

Ok, ~ftp, ~ftp/bin and ~ftp/etc are mode 0755 by default:

$ ls -la /var/spool/ftp
total 10
drwxr-xr-x   5 root  wheel  512 Oct 24 23:36 .
drwxr-xr-x  11 root  wheel  512 Oct 24 23:36 ..
drwxr-xr-x   2 root  wheel  512 Oct 24 23:36 bin
drwxr-xr-x   2 root  wheel  512 Oct 24 23:36 etc
d--x--x--x   2 root  wheel  512 Oct 24 23:36 hidden

(permissions are different on my laptop as I am playing with an
anonymous FTP area, I want to run one very soon for distributing
a complex set of patches for NetBSD for evaluation before submitting
them in a PR.)

...perhaps it would be advisable removing the write permissions on these
directories to meet the requirements in ftpd(8).  Of course, we can leave
them as they are now too.  :-)

No problem at all with the specification file.

Indeed, union mounting fdesc in /dev modifies the permissions on
the file descriptors as we see them.  But certainly fdesc is something
I really like and will continue using.  fdesc is a clean way to manage
file descriptors.

$ mtree -e -f /etc/mtree/NetBSD.dist 
dev:    permissions (0755, 0555)
dev/fd: permissions (0755, 0555)

All perfect now!  ;)

Best regards,
Igor.