> But I don't think this happens _that_ often.  I use passive-mode ftp
> all the time (because my default ftp is Kerberos ftp) and I can't
> recall seeing any time where the ftp failed because passive was
> claimed to be supported when it really wasn't.

Incidentally, Kerberos 5 is switching back to non-passive mode being
the default, for conformity with the rest of the world.  We've
certainly seen old FTP servers at MIT which you can't transfer files
from in passive mode.