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# 1.2.1.21.2 Telnet Server Configurations

Telnet Specific User Configurations

- Maximum Connections:

  - Maximum number of Telnet connections
  - Default value: 2
  - Symbol TCPIP_TELNET_MAX_CONNECTIONS

- Default Socket TX Buffer Size:

  - Size of the telnet socket TX buffer
  - If long messages are sent over the telnet connection the socket should have a large enough buffer to write the data at once
  - Leave 0 for default TCP TX buffer size
  - Default value: 0
  - Symbol TCPIP_TELNET_SKT_TX_BUFF_SIZE

- Default Socket RX Buffer Size:

  - Size of the telnet socket RX buffer
  - If long messages are sent over the telnet connection the socket should have a large enough buffer to receive the data
  - Leave 0 for default TCP RX buffer size
  - Default value: 0
  - Symbol TCPIP_TELNET_SKT_RX_BUFF_SIZE

- Telnet Server Listening Port:

  - Port on which the telnet server is listening
  - Default is TCPIP_TELNET_SERVER_PORT (23) or TCPIP_TELNET_SERVER_SECURE_PORT (992)
  - Adjust as needed
  - Default value: 23
  - Symbol TCPIP_TELNET_LISTEN_PORT

- Telnet Task Rate (in msec):

  - Telnet task processing rate, in milliseconds.
  - The Telnet module will process a timer event with this rate for maintaining its own queues, processing timeouts, etc.
  - The lower the rate (higher the frequency) the higher the module priority and higher module performance can be obtained
  - The value cannot be lower than the TCPIP_STACK_TICK_RATE.
  - Default value: 100
  - Symbol TCPIP_TELNET_TASK_TICK_RATE

- Size of the Internal Print Buffer:

  - Size of the internal print buffer
  - This buffer is used when the telnet console printf style function is called
  - Adjust based on the length of the messages to be formatted with print statements
  - This buffer is created in the automatic stack.
  - Make sure that there is enough stack space for this buffer!
  - Default value: 200
  - Symbol TCPIP_TELNET_PRINT_BUFF_SIZE

- Size of the Internal Line Buffer:

  - Size of the internal line buffer
  - This buffer is used for receiving and assembling the password, authentication and regular characters
  - Adjust based on the length of the commands sent to the telnet server
  - This buffer is created in the automatic stack.
  - Make sure that there is enough stack space for this buffer!
  - Default value: 80
  - Symbol TCPIP_TELNET_LINE_BUFF_SIZE

- Size of the Internal User Name Buffer:

  - Maximum size of the internal buffer to store the user name
  - Adjust based on the length of the user names allowed for the telnet connections
  - A buffer of this size if allocated for each connection to store the login user name
  - Longer user names will be truncated to this size
  - Default value: 15
  - Symbol TCPIP_TELNET_USERNAME_SIZE

- Create Telnet Sockets with NO-DELAY option:

  - Create the telnet sockets with NO_DELAY option
  - Default value: false
  - Symbol TCPIP_TELNET_CONFIG_FLAG_NO_DELAY, TCPIP_TELNET_FLAG_NO_DELAY

- Pass Control Characters to Console:

  - Pass the telnet commands, options, controls, etc. within the messages to the console
  - By default they are removed and only printable characters are sent to the console
  - Enable only for debug or special purposes.
  - Default value: false
  - Symbol TCPIP_TELNET_CONFIG_PASS_CONTROL_CHARS, TCPIP_TELNET_FLAG_PASS_CONTROL_CHARS

- Select telnet Authentication:

  - Select the type of telnet authentication: run time or build time (obsolete)

  - Runtime authentication: this is the default and the PREFERRED case!

    - The telnet module will call a registrated callback to authenticate the users.
    - It is the preferred authentication method.
    - It requires the run time registration of an authentication handler
    - Until the moment the authentication handler is registered any login attempts will fail!

  - The old OBSOLETE build time authentication method

    - TCPIP_TELNET_USERNAME and TCPIP_TELNET_PASSWORD is used
    - This method is DEPRECATED and it will be eventually removed!
    - It is recommended that you leave the setting to false!

  - Note: the build time authentication stores the telnet user and password in clear in the code and it should be avoided!

  - Default value: false (Run time Authentication)

  - Symbol TCPIP_TELNET_OBSOLETE_AUTHENTICATION, TCPIP_TELNET_AUTH_CONFIG

- Connection Info Used for Authentication:

  - The connection info is passed to the authentication handler
  - The handler has access at data showing which IP address requested the connection
  - Used only for run time authentication
  - If false no connection info data is provided to the authentication callback
    - This is useful for the default case when all connections will use the same username/password.
  - If true the authentication callback will contain the connection info data to allow different processing based on the source of the authentication request
  - Note: This flag is relevant only when TCPIP_TELNET_OBSOLETE_AUTHENTICATION == false
  - Default value: true
  - Symbol TCPIP_TELNET_AUTHENTICATION_CONN_INFO

- User Name:

  - Default Telnet user name
  - DEPRECATED. This is used only when there is no authentication callback defined!
  - Use only when TCPIP_TELNET_OBSOLETE_AUTHENTICATION == true
  - Default value: "admin"
  - Symbol TCPIP_TELNET_USERNAME

- Password:

  - Default Telnet password
  - DEPRECATED. This is used only when there is no authentication callback defined!
  - Use only when TCPIP_TELNET_OBSOLETE_AUTHENTICATION == true
  - Default value: "microchip"
  - Symbol TCPIP_TELNET_PASSWORD