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IgorPartola

Omg thank you. Same exact use case and I can’t believe I didn’t realize this.

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It's not as bad as it use to be. In the old days you might do many telnets to get where you want.

Sing the Telnet song!

http://www.poppyfields.net/filks/00222.html

Speaking of telnet, that protocol was actually much richer and had many more features than it would seem at a casual look.

I learned that when implementing a tiny part of the telnet protocol in a retro computer emulator's serial port emulation routines, mostly just to enable character mode and proper (non-)echoing. (I also implemented the RS232 control lines, so that telnet'ing into the port actually behaved like a physical terminal would with respect to carrier detect and all that, but I think there wasn't any overlap with the telnet protocol itself. Maybe flow control.)

See also the even older SUPDUP protocol (RFC 734¹), which I understand had even more features.

1. https://tools.ietf.org/html/rfc734

I wrote a terminal emulator for the Apple ][ + Videx 80 column card in FORTH and reverse polish notation 6502 code, that supported SUPDUP including the line saving protocol that RMS hacked into ITS and EMACS (%TDSAV %TDRES), so Emacs could stash lines on the screen in a memory buffer (on the Apple's bank switched RAM card) and restore them later to paint the screen quickly when scrolling back and forth. (That was great at 300 baud!)

This is just the part of it that interprets SUPDUP codes -- layered on top of the rest of the terminal emulator that emulated H19 (VT52 + character/line insert/delete):

http://www.donhopkins.com/home/archive/forth/supdup.f

Marc Crispin (the author of the SUPDUP RFC #734, who was famous for his catchphrase "MM is not at fault!") also wrote another RFC #748 documenting the Telnet Randomly-Lose Option, which was useful for fuzzball testing.

https://en.wikipedia.org/wiki/Mark_Crispin

https://tools.ietf.org/html/rfc748

   IAC WILL RANDOMLY-LOSE

      The sender  of this command  REQUESTS  permission  to, or confirms
      that it will, randomly lose.

   IAC WON'T RANDOMLY-LOSE

      The sender of this command REFUSES to randomly lose.

   IAC DO RANDOMLY-LOSE

      The sender  of this command  REQUESTS that the receiver, or grants
      the receiver permission to, randomly lose.

   IAC DON'T RANDOMLY-LOSE

      The command sender DEMANDS that the receiver not randomly lose.

Telnet also uses TCP's out of band data mechanism to send "urgent data" and a DATA MARK to interrupt and synchronize with runaway processes, and send important commands around flow control and before buffered data.

https://en.wikipedia.org/wiki/Out-of-band_data

http://www.serverframework.com/asynchronousevents/2011/10/ou...

(Oh, Don Hopkins answering. I read you so often on TUHS!)

Didn’t know that, seems useful. Especially because another comment in this thread since mentioned that they often kill their ssh sessions because of runaway processes.

Overall, it seems to me that a lot was lost when giving up telnet.

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