How to unsupress local echo

Question

I am trying to suppress the local echo of a password in a telnet session by sending 0xFF 0xFD 0x2D (IAC DO SUPPRESS_LOCAL_ECHO). This works fine.

My trouble is en

Answer 1

According to my investigations today:

1. The MS Telnet client accepts 'set localecho' and 'unset localecho' but does nothing with them except record the state. It doesn't send anything on the wire. The real state of the client remains 'no local echo' no matter what you do and what 'd' says.

2. The MS Telnet server sends IAC,WILL,ECHO, and in reply accepts IAC,DO,ECHO, and IAC,DONT,ECHO, but completely ignores them, remaining in WILL ECHO state throughout. You can send IAC,DO,ECHO or IAC,DONT,ECHO later on and it won't even reply.

Accordingly, if you are either using the MS client to speak to a non-MS Telnet server or using another client to speak to the MS Telnet server you better stay in no-local-echo mode, otherwise you will get dual echoing.

Windows Vista 64.