datta@uts.amdahl.com (Diptish Datta) (10/27/90)
Does any one out there know of two machines communicating with the telnet protocol and not using remote echo? If so, then the remote server should not be echoing characters typed in at the client and the local client should echo the keyboard entries to the screen - right? Well, I have a lana analyzer trace of a MVS machine logging in to a Unisys unix machine. The MVS machine seems to negotiate no remote echo but it looks to me like the remote machine echoes data any way. Here is what the echo option negotiation looks like: C <------ will echo S L dont echo ------> E I <------ wont echng the server not to echo E dont echo ------> V N wont echo ------> E T <------ dont echo R The way I read this is that the server offers to echo, the client refuses, and server agrees. Then the client says that he wont echo and server says no problem. Then I see the login prompt from the server and the user id data from the client. The server then echoes the user id right back! Basically the Unisys machine seems to have negotiated no remote echo but echoes anyway. Does any one out there have an explanation? Mail direct to me at datta@amdahl.uts.amdahl.com
srwmcln@windy.dsir.govt.nz (10/31/90)
Many implementations of Telnet are broken in one way or another, often in the area of echo (or other option) negotiation. A common problen is that some refuse to allow, no remote/no local echo. Then there is the 8 bit binary situation...... Many implementations are just copies of other broken implementations, and so it goes on. Clive.