Keil Logo

Technical Support

On-Line Manuals

RL-ARM User's Guide (MDK v4)

RL-RTX RL-FlashFS RL-TCPnet TCP Socket Opening TCP Connection TCP Active Open TCP Passive Open Sending TCP Data Example for Sending Data Multiple TCP Connections UDP Socket Opening UDP Connection Sending UDP Data When DHCP Enabled When ARP Cache Empty Example for Sending Data IP Multicasting Multiple UDP Connections Configuring RL-TCPnet Static Configuration System Definitions Ethernet Network Interface PPP Network Interface SLIP Network Interface UDP Socket TCP Socket BSD Socket HTTP Server Telnet Server TFTP Server TFTP Client FTP Server FTP Client DNS Client SMTP Client SNMP Agent SNTP Client Error Function Runtime Configuration Library Files Using RL-TCPnet Stand Alone With RTX Kernel Event Driven Operation IP Address Assignment Ethernet Interface PPP Interface SLIP Interface Localhost Applications HTTP Server Script Language CGI Functions Ajax Support Using XML XML Example How it works SOAP Support SOAP Interface Large POST Messages Web Pages Default Page Error Pages Web on SD Card Web Update File System Interface Http Caching How it works Internal Web External Web Multi-user Authentication Using RAM File System FCARM File Converter PRINT Directive NOPRINT Directive PAGEWIDTH Directive PAGELENGTH Directive ROOT Directive Telnet Server Command Line Interface Multi-user Authentication Sending Reply Message Short Reply Long Reply Continuous Screen Update TFTP Server File System Interface TFTP Client File System Interface FTP Server File System Interface Multi-user Authentication Supported Commands FTP Client File System Interface SMTP Client SNMP Agent MIB Database MIB Interface MIB Entry MIB Table DNS Resolver Starting DNS Device Drivers Ethernet Driver Interrupt Mode Modem Driver Serial Driver Using Serial Link Cable Connection Modem Connection Windows Dial-up Add Direct Serial Link New Dial-up Connection Configure PPP Dial-up Configure SLIP Dial-up Debugging Enabling Debug Debug Level Redirecting Output Function Overview BSD Routines CGI Routines Ethernet Routines FTP Routines HTTP Routines IGMP Routines Miscellaneous Routines Modem Routines PPP Routines Serial Routines SLIP Routines SMTP Routines SNMP Routines System Functions TCP Routines Telnet Routines TFTP Routines UDP Routines RL-CAN RL-USB Example Programs Library Reference Appendix

Telnet Server

RL-TCPnet has integrated a tiny Telnet Server, which is a command-line oriented application that can be used to remotely connect to your device with the Telnet client.

The following Telnet Server options are configurable from the Net_Config.c configuration file:

  • Telnet Server switch enables or disables the Telnet Server service in your application. It is enabled when this value is set to 1. It should be set to 0 when Telnet Server is not used in your application.
    #define TNET_ENABLE    1
  • Number of Telnet Connections specifies the number of available Telnet sessions. The default value is one, and this enables only one concurrent client connection. You should increase this number if multiple Telnet clients must connect to the Telnet server at the same time.
    #define TNET_NUMSESS   1
  • Port Number specifies the listening TCP port number. The default Telnet server listening port is 23.
    #define TNET_PORTNUM   23
  • Idle Connection Timeout in seconds specifies the interval of user inactivity, after which the connection is closed. In idle connection, no TCP frames are exchanged. A value of 0 disables a disconnection on timeout.
    #define TNET_IDLETOUT  120
    A value of 0 also enables keep-alive mode of TCP socket. After expiration of TCP_DEFTOUT, a TCP socket sends keep-alive probe to remote peer and expects the acknowledge response. Received acknowledge reloads the timeout counter for the socket. If a response is not received after certain number of retries, a connection is closed.
  • Disable Echo switch enables or disables the Telnet Server echo mode. When disabled, the Telnet Server will not echo characters it receives. The echo mode is disabled when this value is set to 1.
    #define TNET_NOECHO    0
  • Enable User Authentication switch enables or disables the Telnet Server authentication with a username and a password. The user authentication is enabled when this value is set to 1.
    #define TNET_ENAUTH    1
  • Authentication Username is the username identification.
    #define TNET_AUTHUSER  "admin"
  • Authentication Password is the default password, that must be stored in Non volatile memory. The user may change the password later.
    #define TNET_AUTHPASSW ""


  • You must also add the Telnet_uif.c user interface module to your project and customize it. This file is in the \Keil\ARM\RL\TCPnet\User folder.
  • When the Telnet server is not enabled, the ARM linker does not link the Telnet support modules to your application and thus reduces the code size and memory usage.
  Arm logo
Important information

This site uses cookies to store information on your computer. By continuing to use our site, you consent to our cookies.

Change Settings

Privacy Policy Update

Arm’s Privacy Policy has been updated. By continuing to use our site, you consent to Arm’s Privacy Policy. Please review our Privacy Policy to learn more about our collection, use and transfers
of your data.