[...identd...]
 What do you mean by "certain protocol errors"? 
  I've noticed
five major classes of errors.
 Doesn't exist
        This is an "ERROR:NO-USER" response.  This should never happen; 
 
Don't forget that a lot of Linux dists were shipping with identd
 configured to send 'UNKNOWN' or 'ERROR:NO-USER' to all requests. 
 
ERROR:HIDDEN-USER or ERROR:UNKNOWN-ERROR I have no beef with; they
don't bother me.  ERROR:NO-USER does (when it's not actually true, of
course).
Anyone shipping an OS with an identd so badly misconfigured as to
return ERROR:NO-USER when it's not actually true is doing its users a
severe disservice (unless putative new users are specifically and
loudly warned of the nonconformance).  Any user un-diligent enough to
run such a distro (or crazy enough to run it even knowing that about
it) is not _my_ problem.  Presumably some people would end up running
it out of ignorance; ignorance has never been an excuse - and
furthermore, that's why such hosts get a "greeting" saying "come back
when you've fixed your identd", so they are pointed at the problem.
  Supposedly this was to improve security... 
Bah.  Idiots.  Returning UNKNOWN-ERROR for all queries has absolutely
no security benefit over simply not running anything on port 113 at
all, and in fact is a security _hazard_ because it's one more daemon to
potentially be cracked through.
I don't mind rejecting mail from those stupid, careless, or crazy
enough to run systems that brokenly.  And as for ignorance, the other
plausible explanation, that's why the error I return to them points
them at the brokenness, so they can cure their ignorance.
Sigh.  Tony's rantings about people not understanding things applies to
software too, I think, for all that he was applying it primarily to
electronics and mechanical gadgetry.
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