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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

Telnet is most often used for remote login. A user typically uses a Telnet client program to open a Telnet connection to a remote server. The server then treats the Telnet client like a local terminal and allows the user to log in and access the server's resources as if the user was using a directly-attached terminal. Telnet is still used this way quite extensively by UNIX users, who often need to log in to remote hosts from their local machines.

It is the client and server devices that decide whether Telnet is used for remote access or for some other purpose. When Telnet is used to access a remote device, the protocol itself is used to:

  • set up the connection between the client and server machines
  • encode data to be transmitted according to the rules of the Telnet Network Virtual Terminal (NVT)
  • facilitate the negotiation and use of options.

Using the RL-TCPnet Embedded Telnet Server, you can build a simple command line interface that enables a Telnet client to access and control the remote embedded system.

Supported Features

The Embedded Telnet server has integrated several advanced features:

  • Access filtering
    allows you to filter out the hosts, which are not allowed to connect to the Telnet Server.
  • Multi-user Authentication
    allows you to add additional user accounts and different access rights for each user.


  • In order to use the Embedded Telnet Server, you have to enable and configure it in the configuration file.
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