[ih] FTP design

[John Kristoff]

The development of ftp over the early years seems to be interesting,
although its cumbersome if not difficult for me to put all of the pieces
together from the early RFCs, because I wasn't there.  Its a subject
that came up here and I thought I would see what I could get out of this
list.

Particularly...

Why the design of separate control/data channels, with each typically
opening in the opposite direction from the other (not in passive mode). 
I thought I remember hearing that it had something to do in part because
of one particular system's design.  Skimming through some of the older
RFCs (e.g. 114), it seems originally this was considered but not the
preferred method.

In the current RFC959 there is mention of having the capability to do
full-duplex transfer of data over the data channel, but as far as I'm
aware you've only ever be able to 'get' or 'put', but not both at the
same time.  Was there or is there a system that piggy-backs a 'put' with
ACKs if it was doing a 'get' or vice versa?

Any additional insights into what might be considered big mistakes in
the design with 20/20 hindsight, or collosal mistakes in intentionally
leaving something out?

John