Foundation or terminal standard

ECHO

Telnet Echo Option

Widely used Documented current use

Controls which side echoes typed characters, especially while entering passwords.

Protocol overview

First seen: 1983
Present-day status: Widely used
In use today?: Yes, with documented current use.
Legacy?: No.
Layer: Foundation or terminal standard
Transport: Telnet option 1
Telnet option: 1
Research validated: 2026-08-29

Current use and fit

A standard part of traditional interactive Telnet sessions.

Implementation essentials

Negotiate direction correctly.
Restore normal echo after secret entry.

Compatibility and safety notes

Incorrect state can expose passwords on screen.
Echo state is independent from transport encryption.

Original specifications and sources

RFC 857 Echo Option Standard
IANA Telnet Options Registry Registry

Where an original site has disappeared, a preservation archive is linked and identified as such. MUDVerse does not claim authorship of the original protocol.