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echoprotocolstelnetrfc

are there specific echo and non-echo telnet ports


I have few doubts regarding telnet and echo which I haven't got so far lucky with google (also to say I have done my homework)

  • Does the telnet specification says that there are specific echo port and specific non-echo port?
  • If yes, Do ports 23 and 10001 differs on that specifically?
  • If conditional yes, is it some version of telnet protocol specific. In other words were those added after some specific iteration of telnet and/or are their fully compliant telnet clients and partially compliant one (regrading echo)?
  • also whats the difference if any between localecho and remote echo? I believe I am talking about echo from server side (remote echo?) but in any case which is what?

I am not sure if there is telnet / protocol specific child stackoverflow site? If yes, can somebody point me there?


Solution

  • The IANA Service Name and Transport Protocol Port Number Registry contains all port number registrations and for Telnet it cites RFC 854 as specification which defines

    Port Assignment
    
      When used for remote user access to service hosts (i.e., remote
      terminal access) this protocol is assigned server port 23
      (27 octal).  That is L=23.
    

    For the Echo Protocol the RFC number RFC 862 which similarily defines

    TCP Based Echo Service
    
    One echo service is defined as a connection based application on TCP.
    A server listens for TCP connections on TCP port 7.  Once a
    connection is established any data received is sent back.  This
    continues until the calling user terminates the connection.
    

    The port number 10001 is registered for "SCP Configuration".