[ih] X.25

[Dave Crocker]

On 10/1/2025 6:23 PM, Jack Haverty via Internet-history wrote:
> Did anybody else play similar games while using the X.25 public 
> network underneath their parts of the Internet? 

For the CSNet phonenet connections, initiation could be from either 
side, and whenever a connection was established, MMDF would ship waiting 
mail outbound and then pickup from the other side. Who initiated was set 
by configuration and therefore mutual agreement.  Verious combinations 
of mixed initiative were used.

This experience fed into the SMTP design discussions, producing the TURN 
command, to effect roughly the same behavior.  The original design had a 
basic security flaw.  For CSNet phone access, there was a login for 
access, so requests to pickup mail had an accountable indentier to 
validate the request.  SMTP did not come with authentication.  The 
eventual fix produced the ETRN command.

Vint participated in the SMTP discussions.  When I first raised the idea 
of adding this capability, there was some silence in the room.  Vint was 
still at DARPA and chimed in: "Submarines!". Thereby making the most 
concise, compelling elevator pitch I've ever heard.


d/

-- 
Dave Crocker

Brandenburg InternetWorking
bbiw.net
bluesky: @dcrocker.bsky.social
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