13 Dec
2016
13 Dec
'16
3:01 p.m.
It's the SGA (suppress go-ahead) negotiation that's necessary to avoid line
mode.
Many telnet clients don't try to negotiate any telnet options if you
connect to a non-standard port, because they assume that you're talking to
something other than a telnet server, and that you therefore want an 8-bit
transparent connection with local line editing. Examples would be to telnet
to an SMTP server, FTP server, etc. for testing purposes.
A telnet client that has that behavior but no provision for overriding it
is defective, and should either be fixed, if possible, or deleted with
prejudice.
My telnet client works just fine for testing SMTP servers etc. I suspect
that it only decides to issue the SGA on ports other than the standard telnet
port when the server at the other end has already revealed that it is a telnet
server by sending out some telnet negotiation from it's side.
(I do recall a customer once insisting to me that I would not be able to use
a telnet client to connect to his SMTP server to test it because the two
aren't compatible or something. At the time, it was something I did every
day of the week but there was no convincing him.)
Regards,
Peter Coghlan.