Table Of Contents
terminal lat remote-modification
slip
To start a serial connection to a remote host by using Serial Line Internet Protocol (SLIP), use the slip command in EXEC mode.
slip [/default] {remote-ip-address | remote-name} [@tacacs-server] [/routing]} [/compressed]
Syntax Description
Command Modes
EXEC
Command History
Usage Guidelines
When you connect from a remote node computer to the EXEC facility on a router and want to connect from the router to a device on the network, issue the slip command.
If you specify an address for the TACACS server by using /default or tacacs-server arguments, the address must be the first parameter in the command after you enter slip. If you do not specify an address or enter /default, you are prompted for an IP address or host name. You can enter the /default keyword at this point.
If you do not use the tacacs-server argument to specify a TACACS server for SLIP address authentication, the TACACS server specified at login (if any) is used for the SLIP address query.
To optimize bandwidth on a line, SLIP enables compression of the SLIP packets using Van Jacobson TCP header compression as defined in RFC 1144.
Your system administrator must configure the system with the ip tcp header-compression passive command for the /compressed command option to be valid in EXEC mode. The ip tcp header-compression command forces header compression on or off. The default is to not compress the packets. The configuration file must have header compression on and the slip /compressed EXEC command must be entered for header compression to occur.
To terminate a session initiated with the slip command, disconnect from the device on the network using the command specific to that device. Then, exit from EXEC mode by using the exit command.
Examples
The following example makes a connection when a default IP address is assigned. Once a correct password is entered, you are placed in SLIP mode, and the IP address is displayed.
Router> slipPassword:Entering SLIP mode.Your IP address is 192.168.7.28, MTU is 1524 bytesThe following example illustrates the prompts displayed and the response required when you use dynamic addressing to assign the SLIP address:
Router> slipIP address or hostname? 192.168.6.15Password:Entering SLIP modeYour IP address is 192.168.6.15, MTU is 1524 bytesIn the preceding example, the address 172.31.6.15 has been assigned as the default. Password verification is still required before SLIP mode can be enabled.
Router> slip /defaultPassword:Entering SLIP modeYour IP address is 192.168.6.15, MTU is 1524 bytesThe following example illustrates the implementation of header compression on the interface with the IP address 172.24.2.1:
Router> slip 172.24.2.1 /compressedPassword:Entering SLIP mode.Interface IP address is 172.24.2.1, MTU is 1500 bytes.Header compression will match your system.In the preceding example, the interface is configured for the ip tcp header-compression passive command, which permits the user to enter the /compressed keyword at the EXEC mode prompt. The message "Header compression will match your system" indicates that the user specified compression. If the line was configured for the ip tcp header-compression on command, this line would read "Header compression is On."
The following example specifies a TACACS server named server1 for address authentication:
Router> slip 10.0.0.1@server1Password:Entering SLIP mode.Interface IP address is 10.0.0.1, MTU is 1500 bytesHeader compression will match your system.telnet
To log in to a host that supports Telnet, use the telnet command in EXEC mode.
telnet host [port] [keyword]
Syntax Description
host
A host name or an IP address.
port
(Optional) A decimal TCP port number; the default is the Telnet router port (decimal 23) on the host.
keyword
(Optional) One of the keywords listed in Table 34.
Command Modes
EXEC
Command History
Usage Guidelines
Table 34 lists the optional telnet command keywords.
With the Cisco IOS implementation of TCP/IP, you are not required to enter the connect or telnet commands to establish a terminal connection. You can enter only the learned host name—as long as the following conditions are met:
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The host name is different from a command word for the router.
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To display a list of the available hosts, use the show hosts command. To display the status of all TCP connections, use the show tcp command.
The Cisco IOS software assigns a logical name to each connection, and several commands use these names to identify connections. The logical name is the same as the host name, unless that name is already in use, or you change the connection name with the name-connection EXEC command. If the name is already in use, the Cisco IOS software assigns a null name to the connection.
The Telnet software supports special Telnet commands in the form of Telnet sequences that map generic terminal control functions to operating system-specific functions. To issue a special Telnet command, enter the escape sequence and then a command character. The default escape sequence is Ctrl-^ (press and hold the Ctrl-Shift-6). You can enter the command character as you hold down Ctrl or with Ctrl released; you can use either uppercase or lowercase letters. Table 35 lists the special Telnet escape sequences.
Table 35 Special Telnet Escape Sequences
Ctrl-^ b
Break
Ctrl-^ c
Interrupt Process (IP)
Ctrl-^ h
Erase Character (EC)
Ctrl-^ o
Abort Output (AO)
Ctrl-^ t
Are You There? (AYT)
Ctrl-^ u
Erase Line (EL)
1 The caret (^) symbol refers to Shift-6 on your keyboard.
At any time during an active Telnet session, you can list the Telnet commands by pressing the escape sequence keys followed by a question mark at the system prompt:
Ctrl-^ ?A sample of this list follows.
In this sample output, the first caret (^) symbol represents the Ctrl key, and the second caret represents Shift-6 on your keyboard:
Router> ^^?[Special telnet escape help]^^B sends telnet BREAK^^C sends telnet IP^^H sends telnet EC^^O sends telnet AO^^T sends telnet AYT^^U sends telnet ELYou can have several concurrent Telnet sessions open and switch between them. To open a subsequent session, first suspend the current connection by pressing the escape sequence (Ctrl-Shift-6 then x [Ctrl^x] by default) to return to the system command prompt. Then open a new connection with the telnet command.
To terminate an active Telnet session, enter any of the following commands at the prompt of the device to which you are connecting:
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•
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Examples
The following example establishes an encrypted Telnet session from a router to a remote host named host1:
Router> telnet host1 /encrypt kerberosThe following example routes packets from the source system host1 to kl.sri.com, then to 10.1.0.11, and finally back to host1:
Router> telnet host1 /route:kl.sri.com 10.1.0.11 host1The following example connects to a host with logical name host1:
Router> host1The following example suppresses all onscreen messages from the Cisco IOS software during login and logout:
Router> telnet host2 /quietThe following example shows the limited number of messages displayed when connection is done using the optional /quiet keyword:
login:User2Password:Welcome to OpenVMS VAX version V6.1 on node CRAWLast interactive login on Tuesday, 15-DEC-1998 11:01Last non-interactive login on Sunday, 3-JAN-1999 22:32Server3)logoutUser2 logged out at 16-FEB-2000 09:38:27.85Related Commands
telnet break-on-ip
To cause the system to generate a hardware BREAK signal on the EIA/TIA-232 line that is associated with a reverse Telnet connection when a Telnet Interrupt-Process command is received on that connection, use the telnet break-on-ip command in line configuration mode.
telnet break-on-ip
Syntax Description
This command has no arguments or keywords.
Defaults
No hardware Break signal is generated when an Interrupt-Process command is received.
Command Modes
Line configuration
Command History
Usage Guidelines
This command causes the system to generate a hardware BREAK signal on the EIA/TIA-232 line that is associated with a reverse Telnet connection. It is useful when a Telnet Interrupt-Process command is received on that connection because it can control the translation of Telnet Interrupt-Process commands into X.25 BREAK indications. It is also a useful workaround in the following situations:
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•
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A hardware BREAK signal is generated when a Telnet BREAK command is received.
Examples
In the following example, line 5 is configured with the telnet break-on-ip command. The location text notes that this line is the location of the high-speed modem. The telnet transparent command sets end-of-line handling.
line 5location high-speed modemtelnet transparenttelnet break-on-ipRelated Commands
telnet refuse-negotiations
To set a line using Telnet to refuse to negotiate full-duplex, remote echo requests on incoming connections, use the telnet refuse-negotiations command in line configuration mode. To disable this function, use the no form of this command.
telnet refuse-negotiations
no telnet refuse-negotiations
Syntax Description
This command has no arguments or keywords.
Defaults
No default behavior or values.
Command Modes
Line configuration
Command History
Usage Guidelines
Use this command on reverse Telnet connections to allow the Cisco IOS software to refuse full-duplex, remote echo option connection requests from the other end. This command suppresses negotiation of the Telnet Remote Echo and Suppress Go Ahead options.
This command does not apply to protocol translation configurations. It is intended for applications in which the router is functioning as a terminal server to allow terminal connections to remote devices through the asynchronous terminal ports of the router. Terminal server connections are those where the user types a command similar to the following to access network resources:
telnet access-server 2005
where access-server is the host name of the Cisco router functioning as a terminal server, and 2005 is the port number on the router to which the remote terminal is connected.
Examples
The following example shows how to set line 5 to refuse full-duplex, remote echo requests:
line 5telnet refuse-negotiationsRelated Commands
telnet speed
To allow negotiation of the transmission speed of the line to a connected device, use the telnet speed command in line configuration mode. To disable this function, use the no form of this command.
telnet speed default-speed maximum-speed
no telnet speed
Syntax Description
Defaults
No default behavior or values.
Command Modes
Line configuration
Command History
Usage Guidelines
Negotiates speeds on reverse Telnet lines. You can match line speeds on remote systems in reverse Telnet, on host machines hooked up to a router used to access the network, or on a group of console lines hooked up to the router, when disparate line speeds are in use at the local and remote ends of the connection. Line speed negotiation adheres to the Remote Flow Control option defined in RFC 1080.
Examples
The following example allows a router to negotiate a bit rate on the line using the Telnet option. If no speed is negotiated, the line will run at 2400 bits per second (bps). If the remote host requests a speed of greater than 9600 bps, then 9600 will be used.
line 5telnet speed 2400 9600Related Commands
telnet sync-on-break
To configure the Cisco IOS software to cause an incoming connection to send a Telnet Synchronize signal when it receives a Telnet BREAK signal, use the telnet sync-on-break command in line configuration mode. To disable this function, use the no form of this command.
telnet sync-on-break
no telnet sync-on-break
This command has no arguments or keywords.
Defaults
No default behavior or values.
Command Modes
Line configuration
Command History
Usage Guidelines
This command causes a reverse Telnet line to send a Telnet Synchronize signal when it receives a Telnet BREAK signal. This option is used very rarely to ensure the ordering of BREAK reception with respect to data characters sent after the BREAK.
Examples
The following example configures the AUX line with the telnet sync-on-break command:
line aux 0telnet sync-on-breakRelated Commands
telnet transparent
To configure the Cisco IOS software to send a CARRIAGE RETURN (CR) as a CR followed by a NULL instead of a CR followed by a LINE FEED (LF), use the telnet transparent command in line configuration mode. To return to the default setting, use the no form of this command.
telnet transparent
no telnet transparent
Syntax Description
This command has no arguments or keywords.
Defaults
CARRIAGE RETURN followed by a LINE FEED.
Command Modes
Line configuration
Command History
Usage Guidelines
This command is useful for coping with different interpretations of end-of-line handling in the Telnet protocol specification.
Examples
The following example causes the Cisco IOS software, when sending a CR, to send a CR followed by a NULL character:
line 7telnet transparentRelated Commands
terminal lat out-group
To temporarily define the list of services to which you or another user can connect, use the terminal lat out-group command in EXEC mode.
terminal lat out-group group-number [start-end] {disabled | enabled}
Syntax Description
Command Modes
EXEC
Command History
Usage Guidelines
To temporarily define the list of services to which you or another user can connect, you define the group code lists used for connections from specific lines. You limit the connection choices for an individual line by defining the group code lists for an outgoing connection. When a user initiates a connection with a local-area transport (LAT) host, the line must share a common group number with the remote LAT host before a connection can be made.
The group code range entered in this command must fall within the group code range already configured for the line.
Examples
The following example defines a group code list for the outgoing group 4:
terminal lat out-group 4, 6-189Related Commands
Logs in to a host that supports Telnet, rlogin, or LAT.
l2f ignore-mid-sequence
Specifies a connection to a particular LAT node that offers LAT services.
terminal lat remote-modification
To set a line running local-area transport (LAT) to be remotely modifiable, use the terminal lat remote-modification command in EXEC mode.
terminal lat remote-modification
Syntax Description
This command has nor arguments or keywords.
Command Modes
EXEC
Command History
Examples
The following example sets line 6 to be remotely modifiable:
terminal lat remote-modification 6Related Commands
Logs in to a host that supports Telnet, rlogin, or LAT.
l2f ignore-mid-sequence
Specifies a connection to a particular LAT node that offers LAT services.
terminal transport preferred
To specify the preferred protocol to use for the current session when a command does not specify one, use the terminal transport preferred command in EXEC mode.
terminal transport preferred {all | lat | mop | nasi | none | pad | rlogin | telnet | v120}
Syntax Description
Defaults
lat (if LAT is not supported, telnet)
Command Modes
EXEC
Command History
10.0
This command first appeared in a release prior to Cisco IOS Release 10.0.
11.2
The following keywords were added:
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Examples
The following example configures the console so that it does not connect when an unrecognized command is entered:
terminal transport preferred noneRelated Commands
Specifies the transport protocol that the Cisco IOS software uses if the user does not specify one when initiating a connection.
tn3270
To begin a TN3270 session, use the tn3270 command in EXEC mode.
tn3270 host
Syntax Description
host
Name or IP address of a specific host on a network that can be reached by the router. The default terminal emulation mode allows access using a VT100 emulation.
Command Modes
EXEC
Command History
Usage Guidelines
Unlike Telnet and local-area transport (LAT) connections, you must enter the tn3270 command to make a connection to an IBM TN3278 host.
To terminate an active TN3270 session, enter the escape sequence (Ctrl-Shift-6 then x [Ctrl^x] by default) and enter the disconnect command at the EXEC prompt. Or log off the remote system by issuing the command specific to that system (such as exit, logout, quit, close, or disconnect).
Examples
The following example establishes a terminal session with an IBM TN3270 host named finance:
tn3270 financetn3270 8bit display
To configure the Cisco IOS software to use the mask set by the data-character-bits {7 | 8} command in line configuration mode or the terminal data-character bits {7 | 8} EXEC command, use the tn3270 8bit display command in line configuration mode. To restore the default 7-bit mask used for TN3270 connections, use the no form of this command.
tn3270 8bit display
no tn3270 8bit display
Syntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Line configuration
Command History
Usage Guidelines
Use the tn3270-character-map command to map between extended EBCDIC or extended ASCII characters.
Examples
The following example configures the Cisco IOS software to use the mask set by the data-character-bits line configuration and EXEC commands on line 5:
line 5tn3270 8bit displayRelated Commands
tn3270 8bit transparent-mode
To configure the Cisco IOS software to use the mask set by the data-character-bits {7 | 8} command in line configuration mode or the terminal data-character bits {7 | 8} EXEC command, use the tn3270 8bit transparent-mode command in line configuration mode. To restore the default 7-bit mask used for TN3270 connections, use the no form of this command.
tn3270 8bit transparent-mode
no tn3270 8bit transparent-mode
Syntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Line configuration
Command History
Usage Guidelines
This command is needed if you are using a file transfer protocol such as Kermit in 8-bit mode or you are using 8-bit graphics, both of which rely on transparent mode.
Examples
The following example configures the software to use the mask set by the data-character-bits line configuration and EXEC commands on line 5:
line 5tn3270 8bit transparent-modeRelated Commands
tn3270 character-map
To convert incoming EBCDIC characters into ASCII characters, use the tn3270 character-map command in global configuration mode. To restore default character mappings, use the no form of this command.
tn3270 character-map ebcdic-in-hex ascii-in-hex
no tn3270 character-map {all | ebcdic-in-hex} [ascii-in-hex]
Syntax Description
ebcdic-in-hex
Hexadecimal value of an EBCDIC character.
ascii-in-hex
Hexadecimal value of an ASCII character.
all
Indicates all character mappings.
Defaults
Disabled
Command Modes
Global configuration
Command History
Usage Guidelines
Use this command to print international characters that are EBCDIC characters not normally printed, including umlauts (¨) and tildes (~). The command first restores default mapping for both EBCDIC and ASCII characters. In the no form of the command, the all keyword resets all character mappings to Cisco defaults.
Table 36 shows the default character mappings between ASCII and EBCDIC in decimal and hexadecimal format.
To convert outgoing ASCII characters into EBCDIC characters, use the keymap command to modify the keymap structure with the tag ebcdic_xx=string, where xx is a hexadecimal value and string is the sequence of characters that send the EBCDIC character.
Examples
The following example creates a two-way binding between an EBCDIC character and an ASCII character:
tn3270 character-map 0x81 0x78Related Commands
Displays ASCII-hexadecimal character mappings.
Displays character mappings between ASCII and EBCDIC.
tn3270 datastream
To enable the TN3270 extended datastream, use the tn3270 datastream command in global configuration mode. To return to the normal TN3270 datastream, use the no form of this command.
tn3270 datastream {extended | normal}
no tn3270 datastream
Syntax Description
Defaults
Normal datastream
Command Modes
Global configuration
Command History
Usage Guidelines
This command causes an "-E" to be appended to the terminal type string sent to the IBM host, which allows you to use the extended TN3270 features.
Examples
The following example shows the supported TN3270 datastream options:
tn3270 datastream ?extended Use extended TN3270 datastreamnormal Use normal TN3270 datastreamtn3270 null-processing
To specify how NULL signals are handled, use the tn3270 null-processing command in global configuration mode. To return to 7171 NULL processing, use the no form of this command.
tn3270 null-processing [3270 | 7171]
no tn3270 null-processing [3270 | 7171]
Syntax Description
3270
(Optional) NULLs are compressed out of the string, as on a 3278-x terminal.
7171
(Optional) NULLs are converted to spaces, as on a 7171 controller.
Defaults
7171 NULL processing
Command Modes
Global configuration
Command History
Usage Guidelines
If a user enters data, uses an arrow key to move the cursor to the right on the screen, and then enters more data, the intervening spaces are filled with NULLs. To specify how NULLs are handled, enter the tn3270 null-processing command either with the 3270 argument, where NULLs are compressed out of the string (as on a real 3278-x terminal) or the 7171 argument, where NULLs are converted to spaces as on a 7171 controller. Enter this command in global configuration.
Examples
The following example shows the two available null processing methods:
tn3270 null-processing ?3270 Use 3270-style null processing7171 Use 7171-style null processingtn3270 optimize-cursor-move
To increase performance between a remote user and a TN3270 host by limiting cursor movement information that is sent to user terminals, use the tn3270 optimize-cursor-move command in global configuration mode. To ensure that all cursor movement information is sent between the terminal and the TN3270 host, use the no form of this command.
tn3270 optimize-cursor-move
no tn3270 optimize-cursor-move
Syntax Description
This command has no arguments or keywords.
Defaults
Cursor movement escape strings are sent to the terminal.
Command Modes
Global configuration
Command History
Usage Guidelines
Issuing this command increases the speed of information transfer between users and TN3270 hosts through an access server.
If you do not issue this command, virtually every byte of information between the terminal and the TN3270 host is prepended and trailed by cursor-movement strings.
Examples
The following example disables status messages to users connected to 3278 terminals:
tn3270 optimize-cursor-moveRelated Commands
tn3270 reset-required
To lock a terminal after input error until the user resets the terminal, use the tn3270 reset-required command in global configuration mode. To return to the default of no reset required, use the no form of this command.
tn3270 reset-required
no tn3270 reset-required
Syntax Description
This command has no arguments or keywords.
Defaults
No reset is required.
Command Modes
Global configuration
Command History
Usage Guidelines
On a 3278-x terminal, the keyboard is locked and further input is not permitted after input error (due to field overflow, invalid entry, and so on) until the user presses the RESET key. Most TN3270 implementations leave the keyboard unlocked and remove any error message on the next key input after the error. Use this command to lock the keyboard until the user performs a reset.
tn3270 status-message
To reenable the display of status messages after they have been disabled, use the tn3270 status-message command in global configuration mode. To save bandwidth on asynchronous lines by not displaying status messages, use the no form of this command.
tn3270 status-message
no tn3270 status-message
Syntax Description
This command has no arguments or keywords.
Defaults
Status messages appear.
Command Modes
Global configuration
Command History
Usage Guidelines
Status messages appear on the console by default. These messages include "System Locked," "Field error," and "System UnLocked" messages. These messages are sent back to the terminal via the TTY line on the access server.
Disabling status messages saves bandwidth on asynchronous lines, which have very low bandwidth.
Examples
The following example disables status messages to users connected to 3270 terminals:
no tn3270 status-messageRelated Commands
Increases performance between a remote user and a TN3270 host by limiting cursor movement information that is sent to user terminals.
tn3270 typeahead
To buffer keyboard data when a 3278 server is in locked mode, use the tn3270 typeahead command in global configuration mode. To disable the typeahead function, use the no form of this command.
tn3270 typeahead
no tn3270 typeahead
Syntax Description
This command has no arguments or keywords.
Defaults
No typeahead
Command Modes
Global configuration
Command History
Usage Guidelines
When typeahead is enabled, the TN3270 client implementation in the Cisco IOS software permits you to continue typing while the system is trying to obtain a response from the TN3270 server. Information you type while a "System Locked" message appears on the terminal is stored in a buffer. After the "System Locked" message disappears, the information is then used as though it were just typed.
Examples
The following example saves user information when "System Locked" messages appear on the screen:
tn3270 typeaheadRelated Commands