bogus "No protocol specified" message

[perryh at pluto.rain.com]

CyberLeo Kitsana <cyberleo at cyberleo.net> wrote:

> On 01/10/2013 05:09 PM, Perry Hutchison wrote:
> > When trying to open an X application on a remote display,
> > I am getting
> > 
> >     No protocol specified
> >     Error: cannot open display: 192.168.200.61:0
> > 
> > The "No protocol specified" message is bogus:  the display is
> > specified correctly*, and the same operation -- with exactly
> > the same setting of DISPLAY -- was working yesterday ...
> > 
> > What does that message actually mean, and how do I fix it?
>
> The error is with regards to the X protocol, not the TCP or UNIX socket
> protocol. Check that both sides have compatible and matching X authority
> information using xauth(1), or that the connecting host or user was
> allowed to connect using xhost(1).

The problem does indeed have something to do with authority/permission,
since "xhost +" fixes it.  (Not the best solution, but sufficient to
demonstrate where the trouble lies.)

I still claim that the message is bogus.  It's now perfectly clear
that both ends know exactly what protocol to use, and they are using
it -- else telling the server to accept all remote connections would
have made no difference.  The message should mention authority and/or
permission, instead of pretending that the client can't figure out
what protocol to use because none was "specified".