HP OpenVMS Systems Documentation

To start TELNET, enter either the TELNET command or the TN3270 command at the DCL prompt.

To use TELNET commands, enter them at the TELNET> prompt.

This section provides complete descriptions of each TELNET command. The related ENABLE and DISABLE commands are presented together (see the description for ENABLE).

Establishes a TELNET connection between your local system and a remote host. You can run one session or 10 or more simultaneous sessions (only one session if you invoke TN3270).

DCL Format

CONNECT host [ port* [ terminal_type ] ]

* Required if you specify terminal type.

UNIX Format

open host [ port ] [ terminal_type ]

Parameters

host

Required.

Remote host to which you want to connect.

port

Optional without terminal_type.
Required with terminal_type.
Default: 23.

TELNET port on the remote host. Specify this parameter if:

• You are invoking TN3270.
• You are connecting to a host that does not use the standard TELNET port.

terminal_type

Optional. Default: model of your physical terminal.

Terminal model that you want your physical terminal to function as. Specify one of the following:

• For a session running TN3270, the terminal model to emulate. Enter one of the following:
  • IBM-3278-2
  • IBM-3278-3
  • IBM-3278-4
  • IBM-3278-5
• For a non-TN3270 session, any terminal type recognized by the remote host, such as VT100, VT200, VT300, VT400, and VT500.

Examples

TELNET> CONNECT MYBUD
      

Establishes a TELNET connection to remote host MYBUD.

TELNET> CONNECT DEBTS 23 IBM-3278-2
      

Establishes a TELNET connection to remote host DEBTS and runs TN3270. Your terminal functions as an IBM-3278-2 model terminal. For syntax reasons, specifying a port number is required.

TELNET> CONNECT 130.180.5.5
      

Establishes a TELNET connection to the host at IP address 130.180.5.5.

TELNET> CONNECT REVIN 31
      

Establishes a TELNET connection to remote host revin . The connection is at port 31 on revin .

% [Ctrl/]]
TELNET> CONNECT QUIK
   .
   .
   .
%
      

During a TELNET session with a UNIX host, pressing Ctrl/] escapes to the TELNET prompt. Another CONNECT command establishes a second session, this one to UNIX host quik .

Creates a TELNET terminal device (TNAx:) and connects to a network device (BGx:). If successful, returns the TNA device name (TNAx:) in the DCL symbol $TELNET_DEVICE. Network input and output operations can then be performed through the created TELNET device using terminal driver $QIO operations.

DCL Format

BIND_SESSION network_device [ /PROTOCOL=option ]

Parameters

network_device

Required.

An existing network device.

Qualifiers

/PROTOCOL=option

Optional. Default: NONE.

Options include:

• NONE
  Data is sent with no interpretation (raw).
• NVT
  Network Virtual Terminal (NVT), TELNET's internal representation of a standard network terminal. NVT format is standard 7-bit ASCII code transmitted in 8-bit octets, the canonical form of data representation used by both the client and server.
• TELNET
  Standard TELNET protocol.
• RLOGIN
  Standard RLOGIN protocol.

Example

TELNET> BIND_SESSION BG393: /PROTOCOL=NVT
      

Establishes an outbound TELNET pseudo device (network terminal) and connects it to a remote listener (port). This is also known as a reverse TELNET connection.

DCL Format

CREATE_SESSION host port [ unit ]

[ /[ NO ]TIMEOUT=option ]
[ /PERMANENT ]
[ /PROTOCOL=option ]

Parameters

host

Required.

Remote host to which you want to connect.

port

Required.

TELNET port on the remote host.

unit

Optional. Default: 0

The decimal number specifying the unit number for the pseudo device (TNAx). The default 0 specifies that TCP/IP Services should pick the next available unit number. If the requested unit number is already in use, the next available unit number is used. In all cases, the software notifies you of the unit number chosen.

Qualifiers

/TIMEOUT

/NOTIMEOUT

Optional. Default: /NOTIMEOUT

• /TIMEOUT
  Creates a TNA device that has the following connection attributes:
  • NOIDLE---The connection is broken when the device is finally deassigned. The device will automatically reconnect when data is written to it.
  • IDLE---Specifies the idle time for the device. If the device is idle for at least the specified amount of time (note that the time has a granularity of one second), then the connection will be broken. Idle means that the device has neither received nor sent any data for the idle period.
  • NORECONNECTION---The device does not automatically retry reconnections if they fail.
  • RECONNECTION---When data is written to the device and the device is not connected, this value determines the interval between reconnection attempts. For example, if an application writes to a TNA with a RECONNECTION-0:1:00, and if the first connection attempt fails, then subsequent connection attempts will be made in 1-minute intervals.

• /NOTIMEOUT
  Creates a TNA device that breaks the connection when the device is finally deassigned (the last channel assignment is deassigned).

/PERMANENT

Optional.

Creates a TNA device that disconnects on deassignment and reconnects on assignment.

/PROTOCOL=options

Optional. Default: NONE. Options include:

• NONE
  Data is sent with no interpretation (raw).
• NVT
  Network Virtual Terminal (NVT), TELNET's internal representation of a standard network terminal. NVT format is standard 7-bit ASCII code transmitted in 8-bit octets, the canonical form of data representation used by both the client and server.
• TELNET
  Standard TELNET protocol.
• RLOGIN
  Standard RLOGIN protocol.

Examples

TELNET> CREATE_SESSION DEBTS 23 2
      

Establishes a network terminal known as TNA2, and connects this device to port 23 on remote host DEBTS.

TELNET> CREATE_SESSION /TIMEOUT=(NOIDLE, RECONNECTION=nn)
      

Creates a device that disconnects on deassignment and reconnects when data is written to it.

TELNET> CREATE_SESSION /NOTIMEOUT
      

Creates a device that is not reusable; the device disconnects on deassignment and is deleted.

TELNET> CREATE_SESSION /TIMEOUT=(IDLE=0:0:30, RECONNECTION=0:2:00)

      

Creates a device that times out after being idle for 30 seconds and that retries connection attempts at 2-minute intervals.

Deletes an outbound TELNET pseudo device (network terminal) created by the CREATE_SESSION command. If the device was not created with the CREATE_SESSION command, the command returns an error.

DCL Format

DELETE_SESSION unit

Parameters

unit

Required.

The decimal number specifying the unit number of the pseudo device (TNx) to be deleted.

Example

TELNET> DELETE_SESSION 2
      

Deletes the network terminal known as TNA2.

Terminates the current remote connection.

If you terminate a session with a remote OpenVMS host, the connection is closed by your local host. However, the process on the remote host is still running. To terminate it, enter a LOGOUT command.

DCL Format

DISCONNECT

UNIX Format

close

Enables or disables the automatic flushing of output when you send the interrupt character.

• Enabled --- The data in the data buffer remains visible until the buffer is empty.
• Disabled --- The data buffer is emptied and the display is terminated. This provides fast system response to the interrupt character.

Default: ENABLE AUTOFLUSH

DCL Format

ENABLE AUTOFLUSH

DISABLE AUTOFLUSH

UNIX Format

toggle autoflush

Enables or disables the sending of the synchronization and interrupt characters in urgent mode.

• Enabled --- The local host sends an interrupt character in urgent mode, and the remote host immediately processes it.
• Disabled --- TELNET sends the interrupt character in sequence with the other characters in the stream, and the remote host processes this character in the sequence received.

Default: DISABLE AUTOSYNCH.

DCL Format

ENABLE AUTOSYNCH

DISABLE AUTOSYNCH

UNIX Format

toggle autosynch

Enables or disables the transmission of data in binary mode.

• Enabled --- The EOL (end-of-line) character is not mapped to Return LF (the carriage return/line feed combination).
  Use ENABLE BINARY when the remote host expects each line to end with a carriage return/line feed combination.
  Binary mode provides interaction when the remote host:
  • Expects special characters.
  • Does not support automatic negotiation of the TELNET binary option.
• Disabled --- EOL is sent as Return LF (the carriage return/line feed combination).

Default: DISABLE BINARY

DCL Format

ENABLE BINARY

DISABLE BINARY

UNIX Format

toggle binary

Enables or disables the sending of carriage returns as Return LF (the carriage return/line feed combination) at the end of each line.

• Use ENABLE CRLF if the remote host expects Return LF at the end of each line.
• Use DISABLE CRLF if the remote host interprets Return as Return LF, which is CR mode.

Default: ENABLE CRLF

DCL Format

ENABLE CRLF

DISABLE CRLF

UNIX Format

toggle crlf

Enables or disables the mapping of received carriage returns. With this mapping, the remote host sends each line with Return LF (the carriage return/line feed combination) at the end of each line.

• Use ENABLE CRMOD if your terminal expects each line to end with Return LF.
• Use DISABLE CRMOD if your terminal expects Return null at the end of each line.

Default: DISABLE CRMOD

DCL Format

ENABLE CRMOD

DISABLE CRMOD

UNIX Format

toggle crmod

Enables or disables the display of data in hexadecimal.

• Enabled --- Data is displayed in both hexadecimal and readable text.
• Disabled --- Data is displayed in readable text.

Default: DISABLE DEBUG

DCL Format

ENABLE DEBUG

DISABLE DEBUG

UNIX Format

toggle netdata

Example

% [Ctrl/Z]  (characters not echoed)
TELNET> enable debug [Return]
TELNET> display [Return]
   .
   .
   .
Will print network data flow in hexadecimal
.
.
.
TELNET>)resume [Return]
SEND [   0] D A
RCVD [   0] D A
RCVD [   0] 746E7069782E6C6B672E6465632E636F6D3E20
% ls [Return]
SEND [   0] 6C
RCVD [   0] 6C l
SEND [   0] 73
RCVD [   0] 73 s
SEND [   0] D A
RCVD [   0] D A
RCVD [   0] 62696E20202020202020...
RCVD [  32] 7074 D A
french.estud.oiseau     russian.estud.ptitsa     fences
typescript     verio
%
      

Escapes from a session with a UNIX host, enables debug mode, resumes the session, and asks for a list of files in the working directory. Both hexadecimal data and readable data are displayed.

Enables or disables the translation of the following terminal control characters in to TELNET protocol sequences:

• Interrupt
• Flush Output
• Are You There
• Kill
• Erase
• Quit

With local characters:

• Enabled --- The local host sends the control characters (in the preceding text) translated into TELNET sequences. For example, Ctrl/T becomes IAC AYT.
  Enabled mode is appropriate when the remote and local hosts implement different control characters. The remote host does not recognize certain control characters. Therefore, the local host interprets these control characters before sending them to the remote host.
• Disabled --- The local host sends these control characters uninterpreted. They are interpreted by the remote host.
  Before you communicate in disabled mode, ensure that the remote and local hosts use the same control characters.

Default: DISABLE LOCAL_CHARS

DCL Format

ENABLE LOCAL_CHARS

DISABLE LOCAL_CHARS

UNIX Format

toggle localchars

Enables or disables the display of option negotiations between the local system and the remote host during the session.

• Enabled --- TELNET displays the option negotiations between your local system and the remote host.
• Disabled --- TELNET does not display the option negotiations. This mode is suitable for most communications.

Default: DISABLE OPTIONS_VIEW

DCL Format

ENABLE OPTIONS_VIEW

DISABLE OPTIONS_VIEW

UNIX Format

toggle options

Closes any open sessions, exits from TELNET, and returns to the DCL prompt.

If you terminate a session with a remote OpenVMS host, the connection is closed by your local host. However, the process on the remote host is still running. To terminate it, enter the LOGOUT command.

DCL Format

EXIT

UNIX Format

quit

Displays online help for TELNET or TN3270 commands.

Format

HELP [ telnet_command ]

Parameters

telnet_command

Optional.

Specific DCL TELNET command about which you want information.

Examples

TELNET> HELP CONNECT
      

Provides information about the CONNECT command.

TELNET> HELP OPEN
      

Displays the message Sorry, no documentation on OPEN .

To get help for a command, enter the DCL command name.

Resumes an open TELNET or TN3270 session that you interrupted with the escape sequence. When you run simultaneous multiple sessions (TELNET only):

• To resume a particular session, specify a session number.
• To resume the active session, omit the session number.
• If no session is active, you must specify a session number.

  Note TELNET interprets the active session as the last session with which you communicated. If that communication ended with you logging out, you have no active sessions. However, you might have other waiting (alive) sessions.

DCL Format

RESUME [ session_number ] [Return]

UNIX Format

[Return]

Parameters

session_number

Optional. Default: the active session.

Use session_number when you run multiple TELNET sessions. It resumes the session with the specified number.

Examples

$ [Ctrl/]] (characters not echoed)
TELNET> SHOW STATUS [Return]
Session  1 Active  Host FINDER
   .
   .
   .
TELNET> RESUME [Return]
$

      

This example:

• Starts at the prompt of remote OpenVMS host FINDER.
• Escapes from FINDER and returns to the local TELNET prompt.
• Issues SHOW STATUS, which displays one active session.
• Returns to FINDER's prompt.

% [Ctrl/]] (characters not echoed)
TELNET> SHOW STATUS [Return]
Session  2 Active  Host LUNA
   .
   .
   .
Session  1 Waiting Host SOLAR
TELNET> RESUME 1 [Return]
%

      

This example:

• Starts at the prompt of UNIX host luna .
• Escapes from luna .
• At the TELNET prompt, issues SHOW STATUS, which displays two active sessions, the active one with luna and another with host solar , whose status is "waiting."
  The RESUME 1 command returns to "waiting" host solar .