[ih] FTP Design

[Dave Crocker]

On 6/30/2012 2:46 PM, Bob Braden wrote:
> John Day wrote:
>
>>  Actually, I believe that Telnet and FTP got an uncommon number of

+1


>>  things right.  I think the idea of having replies that were both
>>  machine and human readable was brilliant.  I forget who came up with
>>  it but I think it was Postel and a couple of others.

What I recall being told was that the textual basis was a) for debugging 
and b) to permit human conduct of protocol sessions from TIPs, or the 
like.  The former was the real win.,


> tcp was designed the way it was for the same reason: symmetry between hosts.

There's no question in my mind that this is correct, but I should note 
that it can have some downsides.

While I was managing the engineering work at Wollongong, we had a site 
visit from a government type wanting to qualify us for a contract.

We stepped through the various tests just fine until he asked us to show 
that the server could send a DO ECHO telnet command to the client.  We 
explained that that wasn't what it was intended for and he pointed to 
the telnet spec citing complete symmetry.

He acknowledged that this wasn't useful for this option but specs are 
specs...  (We hacked the code to pass the test.)

So the rule for symmetry needs to be thoughtfully applied.

d/
-- 
  Dave Crocker
  Brandenburg InternetWorking
  bbiw.net