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                           FTSC INFORMATION   
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   FTSC                            FIDONET TECHNICAL STANDARDS COMMITTEE   
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   Publication:    FTS-4010   
   Revision:       1   
   Title:          The PING and TRACE flags   
   Author(s):      Michiel van der Vlist,   
                   FTSC members and administrator.   
   Issue Date:     2022-12-24   
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   Status of this document   
   -----------------------   
      
     This document is a FidoNet Technical Standard (FTS).   
      
     This document specifies an optional FidoNet standard for the FidoNet   
     community.   
      
     This document is released to the public domain, and may be used,   
     copied or modified for any purpose whatever.   
      
     This document supersedes and replaces FSP-1043.   
     FSP-1043 is preserved in the FTSC reference library as FRL-1040.   
      
      
   ---------------------------------------------------------------------   
   Contents:   
              0. Definitions   
              1. Introduction.   
              2. The problem.   
              3. The solution.   
              4. Considerations   
              A. References   
              B. History   
   ---------------------------------------------------------------------   
      
      
   0. Definitions   
   --------------   
      
     The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL   
     NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL"   
     in this document are to be interpreted as described in [FTA-1006].   
      
      
   1. Introduction   
   ---------------   
      
   The PING functionality as introduced by Ward Dossche just over two   
   decades ago and advertised by the PING flag is a very useful tool   
   in tracing and solving routing problems. This proposal is an update   
   of the original specs and introduces the TRACE flag.   
      
      
   2. The problem   
   --------------   
      
   In the original specification as documented by Ward Dossche in the   
   April 2001 Z2 nodelist trailer and the specification last documented   
   in FTS-5001.006, the PING functionality contains two parts: PING and   
   TRACE. According to that specification systems flying the PING flag   
   should support both PING and TRACE functionality.   
      
   Recent surveys by the author however have shown that not all systems   
   flying the PING flag also support the TRACE functionality. One could   
   argue that current practice is that TRACE functionality is optional.   
      
   Considering that the PING function alone is a very useful tool all   
   by itself for both routing systems and leaf systems and that TRACE   
   is only useful for routing systems, one may conclude that the above   
   current practice works well, but that it is not compliant with the   
   original and current specs.   
      
      
   3. The Solution   
   ---------------   
      
   Split up the PING and TRACE functionality.   
      
      
     PING   
     ----   
      
       Specified as exactly "PING" with no arguments. Nodes flying this   
       flag will adhere to the following functionality:   
      
       If a message destined to user "PING" (case insensitive) arrives   
       at its final destination and this final destination flies the   
       PING flag, then the receiving node will bounce the message back   
       to the original sender clearly quoting all the original via   
       lines.   
      
       If a message destined to "PING" arrives at its final destination   
       but this final destination does _not_ fly the PING flag then the   
       message may be deleted from the system without further action.   
      
      
     TRACE   
     -----   
      
       Specified as exactly "TRACE" with no arguments. Nodes flying this   
       flag will adhere to the following functionality:   
      
       If a message destined to user "PING" (case insensitive) arrives   
       at a node which flies the TRACE flag but is merely passing   
       through to another destination then the in-transit node will   
       notify the sender of this occurrence, clearly quoting the via   
       lines, and forward the original mail unaltered towards its final   
       destination.   
      
      
       For both PING and TRACE responses, the sender's name must never   
       be "PING" and the responses must never be addressed to "PING".   
      
      
   4. Considerations   
   -----------------   
      
   Making the TRACE function optional by separating the flags, is an   
   encouragement for developers and script writers to join the project.   
   They can choose to only implement the PING functionality and leave   
   TRACE functionality for later or omit it completely without   
   violating the specs. This will hopefully make more sysops join   
   the PING club.   
      
   Splitting up the PING and TRACE functionality by introducing the   
   TRACE flag is backward compatible. Systems flying the PING flag   
   that do not support TRACE need do nothing, they are compliant   
   with the new specs. Systems flying the PING flag that support   
   both PING and TRACE functionality may add the TRACE flag to their   
   listing. But if they do not, no harm is done, they are still   
   compliant with the new specs, it just does not advertise all   
   functionality.   
      
      
   A. References   
   -------------   
      
      
     [FTS-5]    "The distribution nodelist".   
                Ben Baker, Rick Moore, and David Nugent.   
                1996-02-27. Obsoleted by FTS-5000.   
      
     FTS-5000]  "The distribution nodelist".   
                FTSC Members, Administrator, and Honoured Guests.   
                2014-01-23.   
      
     [FTS-5001] "Nodelist flags and userflags".   
                FTSC Members, Administrator, and Honoured Guests   
                2017-08-13.   
      
                A PING robot survey.   
                Michiel van der Vlist.   
                Fidonews 38:07, 2021-02-15.   
      
                Ping robot survey, a follow up.   
                Michiel van der Vlist.   
                Fidonews 38:15, 2021-04-12.   
      
      
   B. History   
   ----------   
      
     Rev.1, 2022-12-24: Initial release.   
      
      
      
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