Tunnel Accept Mode controls how a tunnel behaves when a connection attempt originates from the network.
For more information on Protocol SSH, see the SSH Server: Authorized Users page.
For more information on Protocol SSL, see the SSL page.
A Tunnel in Accept Mode can be started in a number of ways:
Disabled: never started.
Always: always started.
Any Character: started when any character is read on the Serial Line.
Start Character: started when the Start Character is read on the Serial Line.
Modem Control Asserted: started when the Modem Control pin is asserted on the Serial Line.
Modem Emulation: behavior is governed by the ATS0 or Incoming Connection setting.
When the Start Character is received on the Serial Line, it enables the tunnel to listen for a network connection.
The Start Character may be designated as a single printable character or as a control character.
Control characters may be input in any of the following forms:
<control>J or
0xA (hexadecimal) or
\10 (decimal).
Enabling Flush Start Character prevents forwarding of a start character from the Line into the network.
Disabling Flush Start Character allows forwarding of a start character from the Line into the network.
The Local Port value can be overridden. By default, it is 10001 for Tunnel 1, 10002 for Tunnel 2, and so on.
Blank the display field to restore the default.
The Protocol used on the connection can be one of SSH, SSL, Telnet, TCP, or TCP with AES.
If security is a concern it is highly recommended that SSH be used. When using SSH, both the SSH Server Host Keys and SSH Server Authorized Users must be configured.
The Credentials specifies the name of the set of RSA and/or DSA certificates and keys to be used for the SSL connection.
The TCP Keep Alive timer specifies how often to probe the remote host in order to keep the TCP connection up during idle transfer periods.
Enter 0 to disable.
Blank the display field to restore the default.
There are two Advanced Encryption Standard (AES) Encryption Keys used for Accept Mode Tunneling. One Key is used for encrypting outgoing data and the other Key is used for decrypting incoming data.
These AES Keys are a fixed 16, 24 or 32 bytes in length. Each key can be entered in Text or Hexadecimal form. Keys are stored and exchanged in Hexadecimal form only.
Text form is a simple string of up to 32 ASCII characters.
The Hexadecimal form takes up to 32 byte specifications
separated by spaces. A byte specification comprises two nibble
specifications with no intervening space. A nibble specification
is a single digit from 0 to 9 or from "a" to "f" (representing
10 through 15).
Example Hexadecimal key:
12 34 56 78 9a bc de f0 01 02 03 04 05 06 07 08
To remove a key, delete <Configured> in the display.
Note that the Keys are shared secret keys so they must be known by both sides of the connection and kept secret.
This device also supports SSH using AES Encryption as an alternative to secure tunneling. It is recommended that SSH be used because it does not require configuring shared secret keys and is a more secure standards based protocol.
The Initial Send data will be sent out the network upon connection establishment before any data from the Line. It may contain one or more Directives of the form %<char>.
The Initial Send string can be entered in Text or Binary
form. The Binary form allows square
braces [ ]
to enclose one or more character designations separated by
commas. Use straight decimal numbers up to 255 or hexadecimal numbers prefixed
with 0x up to 0xFF within the square braces.
To specify an open brace in binary mode, use two in a row. Example (in
Binary mode): AB[255,0xFF]C[[D]
Results in a string containing
binary values where the dots appear: AB··C[D]
Directives
%i | local IP address |
%m | MAC address |
%n | network interface name |
%p | local port |
%s | serial number |
%% | % |
Flush Serial applies at the time when a connection is accepted from the network.
If Enabled, any buffered characters from the Serial Line will be discarded when a connection is accepted.
If Disabled, any characters received on the Serial Line will be buffered and sent after a connection is accepted.
Block Serial may be enabled for debugging purposes.
If Enabled, incoming characters from the Serial Line will NOT be forwarded to the network. Instead, they will be buffered and will eventually flow off the Serial Line if hardware or software flow control is configured.
If Disabled (the normal setting), incoming characters from the Serial Line are sent on into the network. Any buffered characters are sent first.
Block Network may be enabled for debugging purposes.
If Enabled, incoming characters from the network will NOT be forwarded to the Serial Line. Instead, they will be buffered and will eventually flow off the network side.
If Disabled (the normal setting), incoming characters from the network are sent on into the Serial Line. Any buffered characters are sent first.
The Password can be up to 31 characters in length and must contain only alphanumeric characters and punctuation. When set, clients must send the correct password string to the unit within 30 seconds from opening network connection in order to enable data transmission. The password sent to the unit must be terminated with one of the following:
If Prompt for Password is set to Enabled, the user will be prompted for the password upon connection.
Email on Connect comes into play when an accept mode tunnel is established. If an Email profile number has been selected, an email notification based on that profile will then be sent.
Email on Disconnect comes into play when an accept mode tunnel is disconnected. If an Email profile number has been selected, an email notification based on that profile will then be sent.