Telnet Negotiable Options

Many of the obtions listed above are self-evident, but some call for more comments.

Suppress Go Ahead

-- The original telnet implementation defaulted to "half duplex" operation. This means that data traffic could only go in one direction at a time and specific action is required to indicate the end of traffic in one direction and that traffic may now start in the other direction. (This similar to the use of "roger" and "over" by amateur and CB radio operators.) The specific action is the inclusion of a GA character in the data stream.

Modern links normally allow bi-directional operation and the "suppress go ahead" option is enabled.

echo

--

The echo option is enabled, usually by the server, to indicate that the server will echo every character it receives. A combination of "suppress go ahead" and "echo" is called character at a time mode meaning that each character is separately transmitted and echoed.

There is an understanding known as kludge line mode which means that if either "suppress go ahead" or "echo" is enabled but not both then telnet operates in line at a time mode meaning that complete lines are assembled at each end and transmitted in one "go". * linemode

This option replaces and supersedes the line mode kludge.

remote flow control

--

This option controls where the special flow control effects of Ctrl-S/Ctrl-Q are implemented.