The z/OS® UNIX Telnet server is started by inetd for each incoming Telnet connection. When the Telnet session is complete, the z/OS UNIX Telnet server will exit. Each active Telnet session will have a separate instance of the Telnet server which will communicate with the Telnet client.
The z/OS UNIX inetd daemon does not propagate environment variables other than PATH and TZ to its child processes, so the NLSPATH and LANG environment variables cannot be used to point to a different message catalog.
When a z/OS UNIX Telnet session is started up, otelnetd sends Telnet options to the client side that indicate a willingness to do the following options:
This option indicates that the client is willing to send 8 bits of data, rather than the normal 7 bits of network virtual terminal data.
When the LINEMODE option is enabled, a WILL ECHO or WONT ECHO is sent to the client to indicate the current state of terminal echoing. When terminal echo is not wanted, a WILL ECHO is sent to indicate that Telnet takes care of echoing any data that must be echoed to the terminal, and then nothing is echoed. When terminal echo is wanted, a WONT ECHO is sent to indicate that Telnet is not doing any terminal echoing, so the client can do any terminal echoing that is needed.
When a DO LOGOUT is received, a WILL LOGOUT is sent in response and the Telnet session is shut down.
This option indicates that it will not be sending IAC GA, the go ahead command.
Indicates a willingness to send the client, upon request, the current status of all Telnet options.
Whenever a DO TIMING-MARK is received, a WILL TIMING-MARK is the response. It is used only in kludge linemode support.
Indicates a willingness to encrypt the data stream.
Sent to indicate that Telnet is willing to receive an 8-bit data stream.
If a WILL ECHO is received, a DONT ECHO will be sent in response.
Indicates a desire to be able to request environment variable information. (See RFC 1408.)
Requests that the client handle flow control characters remotely.
Supports requests that the client do line-by-line processing.
Requests that the client inform the server when the window size changes.
Indicates a desire to be able to request environment variable information. (See RFC 1572.)
Indicates that it does not need to receive IAC GA, the go ahead command.
Indicates a desire to be able to request the name of the type of terminal that is attached to the client side of the connection.
Indicates a desire to be able to request information about the speed of the serial line to which the client is attached.
Only supported if the client responded with WONT LINEMODE. If the client responds with WILL TM, then it is assumed that the client will support kludge linemode. It is not used for any other purposes.
Indicates a desire to be able to request the name of the X Window System display that is associated with the Telnet client.
Indicates a willingness to receive authentication information for automatic login.
Indicates a willingness to decrypt the data stream.