ANSI/SSH Host Configuration. Zebra Software
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CHAPTER 5 ANSI/SSH HOST
CONFIGURATION
ANSI/SSH HOST CONFIGURATION
ANSI Function Key and Arrow Key Mappings Options Screen . . . . . . . . . . . . . . . . . . . 5-12
5
ANSI/SSH Host Configuration 5 - 3
Overview
The TekTerm Server manages the radio link, caches data going to and from the mobile devices, and supervises the hand-off of devices as they move from one base to another. SSH provides a secure shell for the
ANSI connection.
Figure 5-1
Method 1
Figure 5-2
Method 2
5 - 4 TekTerm Server Software User Manual
General Host Options
Field
Name
Enabled
Emulation and protocol
Terminal range
Auto terminal number assignment (not supported by Direct
TCP)
Description
The unique name of the host.
Default: Unnamed Host
When selected the host task is started when the TekTerm Server starts.
Emulation and protocol combination for this host.
Select: ANSI/SSH
Terminal number range that communicates with this host.
Range: 1 to 3840. For S900L range is 1 to 50.
Default: 1 to 32
For information on selecting the terminal range see Chapter 19: “Setting Terminal
Numbers on the General Host Options Screen”
When selected, TekTerm Server assigns terminal numbers to all mobile devices that use this session.
When not selected, terminal numbers must be assigned on the mobile devices.
Default: Selected.
ANSI Emulation Options Screen
Field
Maximum Screen Size
(rows x columns)
Host Timeout
Description
The maximum dimensions of the mobile device screen. These screen dimensions are used to reserve memory for screen caching when page saving is enabled.
Rows: 4 to 60
Columns: 10 to 132
Default: 24 x 80
When Page Saving is enabled, the host timeout in 60ths of a second.
Values: 0 - 255
Default: 15
For more information see Page Saving on page 5-6
.
Field
Escape Timeout
Threshold
Echo
Function Key
Remapping
ANSI/SSH Host Configuration 5 - 5
Description
The escape timeout in 60ths of a second. This is the length of time that the
TekTerm Server holds an ESC while waiting for another character. If another character is received within this time the pair of characters are treated as an escape sequence. If another character is not received within this time, the ESC is sent on to its destination.
Host to Terminal:
When enabled, if Page Saving is enabled, Escape Timeout is ignored, and dangling escapes are carried over to the next screen.
When enabled, if Page Saving is not enabled, Escape Timeout applies.
Terminal to Host:
When enabled, the timeout is applied.
Values: 0 to 255
Default: 12
It is recommended that this parameter be left at its default value.
For more information see Page Saving on page 5-6
.
When Page Saving is selected, this is the minimum number of bytes that must be received from the host before the TekTerm Server treats the data as a new saved page.
Values: 0 to 999
Default: 200
For more information see Page Saving on page 5-6
.
When selected smart-echo is enabled.
Smart echo reduces the amount of data sent to the mobile device by decreasing the number of radio transmissions.
When smart echo is not enabled, for a character mode application, each keystroke is sent to the host in one transmission, and the character is echoed by the host in another transmission.
When smart echo is enabled, the TekTerm Server does not send the host echo to the mobile devices if it matches the data sent from the mobile device. Thus, the number of radio transmissions is reduced.
This mode also reduces, or eliminates, the delay between typing a character on the keyboard and displaying the character echoed by the host. The maximum number of characters waiting for echo is 25. Any additional characters are sent to the host but not displayed.
Smart echo
must also be enabled on the mobile device.
Default: Selected.
When selected, the TekTerm Server remaps the function keys for this host connection as defined in the ANSI Function Key and Arrow Key Mappings
Options Screen
.
Default: Not selected.
For information on function key remapping see
.
5 - 6 TekTerm Server Software User Manual
Field Description
Arrow Key Remapping When selected, the TekTerm Server remaps the arrow keys for this host connection as defined in the ANSI Function Key and Arrow Key Mappings
Options Screen
.
Default: Not selected.
For information on arrow key remapping see
Page Saving When selected, the TekTerm Server uses page saving, reducing data transmitted to the mobile devices.
The TekTerm Server maintains an image of each page stored on the mobile device. After receiving an application screen, the TekTerm Server tries to match the screen with a stored page. If the page is already in the mobile device, the
TekTerm Server instructs the mobile device to redisplay its stored copy of the page; minimal data is sent across the radio link for that page. If the TekTerm
Server finds no match for the page, the complete page is sent to the mobile device.
If a page is close enough to a saved one (close enough being defined by the
Threshold
setting) then only the redisplayed, and the changed, data are sent, resulting in reduced data transmission.
When page saving is enabled, the number of saved pages is that which is set on the mobile device. Refer to the appropriate user manual for details.
Page Saving consider
Double Byte
Characters
RLE
Convert 7 to 8 Bits
Default: Selected.
When selected a double byte character half is replaced with a space, preventing problems with mobile device screen displays.
While using double byte character sets (for example, Chinese or Korean), the page saving function can cause a double byte character to be partially overwritten. This can cause unprintable screen data and unintended characters; and may cause the mobile device to shift data on the screen.
Select this checkbox only when using double byte character sets.
Default: Not selected.
When selected, the TekTerm Server uses run-length encoding (RLE) on the data it sends across the radio link.
RLE compresses repeated characters going from the host to the mobile device. If repeated characters are found in the data stream, the first one is sent, followed by a short escape sequence (3 or 4 characters) which tells the mobile device how many times to repeat this character. In this way RLE compresses the data and decreases the total amount of radio link traffic.
Default: Not selected.
When selected, the TekTerm Server converts 7-bit control sequences to their 8-bit equivalents in ANSI data streams going to the mobile devices. This replaces 7-bit two-character escape sequences with a single equivalent 8-bit character, compressing the data. For example, the escape sequence ESC [ is converted to CSI.
Default: Not selected.
ANSI/SSH Host Configuration 5 - 7
Field Description
Lower Character Set
(GL)
This is the character set to be used for the first 128 character codes (decimal 0 to
127, hex 00 to 7F). This should be set to the same character set as selected in the mobile devices. This parameter is only used when page saving is enabled.
Available character sets are:
ASCII, DEC_Multi, DEC_Graphical, British_DEC, Danish_DEC, Dutch_DEC,
Finnish_DEC, French_DEC, French_CDN_DEC, German_DEC, Italian_DEC,
Portuagal_DEC, Spanish_DEC, Swedish_DEC, Swiss_DEC, Arabic, Thai, and a
Not Listed
selection.
Default: ASCII
Upper Character Set
(GR)
Terminal Initialization
Data
This is the character set to be used for the second 128 character codes (decimal
128 to 255, hex 80 to FF). This should be set to the same character set as selected in the mobile devices. This parameter is only used when page saving is enabled.
Available character sets are:
ASCII, DEC_Multi, DEC_Graphical, British_DEC, Danish_DEC, Dutch_DEC,
Finnish_DEC, French_DEC, French_CDN_DEC, German_DEC, Italian_DEC,
Portuagal_DEC, Spanish_DEC, Swedish_DEC, Swiss_DEC, Arabic, Thai,
Latin_, Latin_2, Latin_3, Latin_4, Latin_5, Latin_6, Cyrillic_ISO, Arabic_ISO,
Greek_ISO, Hebrew_ISO, and Thai_ISO.
Default: DEC_Multi
As soon as communication is established between a mobile device and the
TekTerm Server, this string is sent to the mobile device.
Default: None.
Host Initialization Data As soon as communication is established between the host and the TekTerm
Server, this string is sent to the host.
Default: None.
ANSI SSH Protocol Options Screen
The SSH (Secure Shell) protocol allows full negotiation of encryption, integrity, key exchange, compression, and public key algorithms and formats. All the algorithms used are well-known and well-established, with cryptographically sound key sizes.
Every SSH connection involves two authentications, which are performed via public key encryption: the client verifies the identity of the SSH server (server authentication), and the server verifies the identity of the user requesting access (user authentication). Once authentication takes place, bulk transfer of data can proceed using private key encryption. Public key encryption is used to distribute the private key to the client.
In this implementation the host is the SSH server, and the TekTerm Server behaves as the client on behalf of each mobile device.
The TekTerm Server implements OpenSSH.
5 - 8 TekTerm Server Software User Manual
Field
Host Address
Host Port
Terminal Type
Close Host session on
Terminal reset
Connect Without User
Action
Description
The IP address of the host.
Default: None.
Note:
If the host address is not an IP address, the host address must be resolvable by the TekTerm Server: The TekTerm Server must be able to obtain an IP address for it. For example, the host name may correspond to an entry in the TekTerm
Server host table, or the TekTerm Server may be able to query a domain name server.
The port number on the host for this connection.
Values: 1 to 65535
Default: 22
The type of terminal to be emulated by the TekTerm Server. This must be the same as the definition on the host.
Default: xterm
When selected, all host sessions close when the mobile device resets.
When not selected, the sessions remain open, if the mobile device resets.
Default: Not selected.
When not selected, SSH sessions from the mobile devices to the host must be initiated manually from the mobile devices.
When selected, the TekTerm Server initiates one SSH session from each mobile device whose terminal number is mapped to this host. Additional sessions may be initiated from each mobile device to the host, but they must be initiated manually.
These sessions are only initiated for mobile devices which are online (that is, turned on and operating properly on the RF network).
The username and password is identical for all SSH sessions automatically logged in to this host.
To use this feature Username (saved so users will not be prompted) and
Password (saved so users will not be prompted)
must be configured.
Default: Not selected.
ANSI/SSH Host Configuration 5 - 9
Field
Connect Prompt
Username Prompt (not used if username is configured)
Password Prompt (not used if password is configured)
Description
The text presented to the user to request a login.
Non-printable characters, such as are used in escape sequences, are allowed.
These characters can be entered using either octal or hexadecimal digits.
An octal escape sequence takes one of the forms:
\0d or \0dd or \0ddd
where each d can be any digit 0 to 7.
A hexadecimal escape sequence takes one of the forms:
\xh or \xhh
where each h can be 0 to 9, or any of a to f or A to F.
Each of these numeric escape sequences encodes one character. For example, the sequence \033abc becomes the character array {033,'a','b','c',0}
Values: Any ASCII string. Maximum 60 characters
Default: Press ENTER to login.
Notes:
If the octal ddd is greater than decimal 256, the code value of the represented character will be the remainder of decimal ddd/256.
\0
is considered as a character with a code value of 0.
Default: Press ENTER to connect.
The prompt string that is sent to the mobile device when the host requests a login.
Default: Username:
The prompt string that is sent to the mobile device when the host requests a login
password. This field is not needed when Password (saved so users will not be prompted) on page 5-10
is configured.
Default: Password:
5 - 10 TekTerm Server Software User Manual
Host Validation
Each SSH host has a host key which is used during the key exchange portion of authentication to verify that the client is really talking to the correct server. For this to be possible, the TekTerm Server should have previous knowledge of the SSH host public key.
Field
Automatically accept new host key
Automatically accept changed host key
Host Key
Description
When selected, the public key, sent by the host when the connection is initiated, is not validated.
When not selected, the public key received from the host when the connection is initiated is checked against the contents of Host Key.
Default: Selected.
For more information see Host Key on page 5-10
.
When the public key is changed on the host, the new public key is sent to the
TekTerm Server.
When selected, the new key is not validated.
When not selected the new public key is checked against the contents of Host
Key
. Host Key must be entered manually.
Default: Selected.
For more information see Host Key on page 5-10
.
The public key of the host.
This is entered only if Automatically accept new key and Automatically accept
changed key
are not selected.
Default: None.
User Authentication
Field
Username (saved so users will not be prompted)
Password (saved so users will not be prompted)
Description
The username sent to the host, when the host requests it. The same username is provided for all mobile devices using this connection.
Default: None.
Note:
This field is not needed if
Username Prompt (not used if username is configured) on page 5-9
is configured.
The password sent to the host, when the host requests it. The same password is provided for all mobile devices using this connection.
Default: None.
Note:
This field is not needed if Password Prompt (not used if password is configured) on page 5-9
is configured.
ANSI/SSH Host Configuration 5 - 11
Field
Public key authentication enabled
Private key file name and path
Private key passphrase
Keyboard-Interactive authentication enabled
Host Prompt 1
Auto Response 1
Host Prompt 2
Auto Response 2
Host Prompt 3
Auto Response 3
Description
When selected, the TekTerm Server attempts public key authentication.
SSH2 only.
Default: Not selected.
The filename, and its path, where the private host key is stored on the
TekTerm Server.
The private host key is obtained from the host administrator.
Default: None.
The passphrase used to protect the private key.
The private key passphrase is obtained from the host administrator.
Default: None.
When selected, keyboard-interactive authentication is enabled.
When selected, the three sets of prompt and response in the following fields are active.
Default: Selected.
When this string is received from the host, the string in Auto Response 1 is sent to the host.
Default: None.
See Host Prompt 1.
Default: None.
When this string is received from the host, the string in Auto Response 2 is sent to the host.
Default: None.
See Host Prompt 2.
Default: None.
When this string is received from the host, the string in Auto Response 3 is sent to the host.
Default: None.
See Host Prompt 3.
Default: None.
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Advanced SSH options
Field
Allow SSH version 1
Cipher List
Compression
Description
When enabled, the SSH1 protocol is used.
When not enabled, the SSH2 protocol is used.
Default: Not selected.
The cipher is negotiated by the host and the TekTerm Server. It is chosen from among the ciphers listed in this field.
Applies to SSH2 only.
Default: aes256-ctr, aes192-ctr, aes128-ctr, aes256-cbc, aes192-cbc,
aes128-cbc, blowfish-cbc, 3des-cbc
When selected, if the host supports compression, then the level of compression is negotiated by the host and the TekTerm Server.
Applies to SSH2 only.
Default: Not selected.
ANSI Function Key and Arrow Key Mappings Options Screen
Function Keys
Each of the function key text boxes contains a code that is sent to the host when the corresponding function key is pressed on the mobile device.
Each code sequence is terminated by a NULL. NULLs are not transmitted by the TekTerm Server.
Arrow Keys
Each of the arrow key text boxes contains a code that is sent to the host when the corresponding arrow key is pressed on the mobile device.
Arrow key remapping also exists on the mobile devices, but is applicable only to Telnet and SSH direct connections.
Function-key remapping and arrow-key remapping can be enabled, and operate, independently of each other.
Arrow key sequences sent from the mobile device can be switched between Application mode and Cursor Key
mode
by the DECCKM command sent by the host. The sequences are CSI?1h and CSI?1l.
TekTerm Client, on the mobile device, has a DEC Cursor Keys setting in the Keyboard Modes menu where the mode can be selected.
The default arrow key sequences (in Psion ANSI debug format) are:
In Cursor-Key Mode
Up arrow
Down arrow
Right arrow
Left arrow
7-Bit
(1b)[A
(1b)[B
(1b)[C
(1b)[D
8-Bit
(9b)A
(9b)B
(9b)C
(9b)D
ANSI/SSH Host Configuration 5 - 13
In Application Mode
Left arrow
Right arrow
Up arrow
Down arrow
7-Bit
(1b)OA
(1b)OB
(1b)OC
(1b)OD
8-Bit
(8f)A
(8f)B
(8f)C
(8f)D
These sequences are remapped by the TekTerm Server to 4 configurable sequences, each a minimum of 5 hexadecimal characters long. A null entry terminates the map-to sequence; it is not necessary to transmit nulls.
The default values for arrow key mappings are the 7-bit Cursor key Mode values. The TekTerm Server recognizes both the 7-bit and the 8-bit forms of the key sequences.
The same escape timeout applies to arrow key remapping as to function key remapping.
The cursor key mode setting in the mobile device is ignored by the TekTerm Server. If the host changes the key sequence using DECCKM, the TekTerm Server continues to remap the new key sequences: With arrow key mapping enabled, DECCKM has no net effect.
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