by Darius Kazemi, November 24 2019

In 2019 I'm reading one RFC a day in chronological order starting from the very first one. More on this project here. There is a table of contents for all my RFC posts.

Simplifying Telnet

RFC-328 is titled “Suggested Telnet Protocol Changes”. It's authored by Jon Postel of UCLA and dated April 29, 1972.

The technical content

Postel opens this RFC with a declaration: the suggestions he makes in this document will be assumed to be official if there is not “substantial negative responne” in the next two weeks.

He proposes that the concept of a “minimum Telnet implementation” as described in RFC-318 be dropped. Essentially, he argues that having a minimum implementation means that there are two standards, which has massive knock-on effects on the whole network.

He proposes that you shouldn't be able to switch away from ASCII as your data type, because if you do, then you're no longer communicating with Telnet! You might as well just hang up at that point; there is “no way to specify how to get back to ASCII or Telnet thus the conversation is "out of control"”.

He proposes getting rid of the HIDE YOUR INPUT signal. It's supposed to be sent to the client as a way to hint that further input should be “hidden” in whatever way makes sense for your terminal. Remember some of these terminals are physical typewriters, hiding input is hard! Basically Postel is saying that this is too complex and not really all that helpful and it should be axed.


I generally approve of any set of proposals where all of the proposals involve simplification of a protocol by removal of features.

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About me

I'm Darius Kazemi. I'm an independent technologist and artist. I do a lot of work on the decentralized web with ActivityPub, including a Node.js reference implementation, an RSS-to-ActivityPub converter, and a fork of Mastodon, called Hometown. You can support my work via my Patreon.