Re: [Qemu-discuss] Confusing use of VNC port

[Dale R. Worley]

> From: Brian Rak <address@hidden>
> 
> On 7/25/2014 1:59 PM, Dale R. Worley wrote:
> >> From: Brian Rak <address@hidden>
> >>
> >> Failed to start VNC server on `127.0.0.1:4105': Failed to bind socket:
> >> Address already in use
> >>
> >> This error message is *highly* confusing.  '127.0.0.1:4105' in any other
> >> software would mean it was trying to bind to 127.0.0.1, port 4105.  In
> >> qemu's terms, it really means port 10005.  Why is this like this?
> >>
> >> Is there any reason this can't just refer to the actual port it's trying
> >> to bind?
> > For that matter, where did the "4105" come from?
> 
> We run multiple instances per machine, so we have to assign unique VNC 
> ports to all of them.  We pass this in (via libvirt), via the command 
> line arg '-vnc 127.0.0.1:4105'.  The port number there is also 
> confusing, but I realize it would not be backwards compatible to change 
> how it behaves.  It's not as confusing in the command line, because we 
> rarely need to look at it.

One way to rephrase it would be something like this:

    Failed to start VNC server on VNC display `127.0.0.1:4105'
    IP address 127.0.0.1 listening port 10005:
    Failed to bind socket: [etc.]

It shows the effective VNC display name (which may have a DNS host
name), as well as the actual IP address Qemu thinks that it translates
into, and the port.  That makes it clear what the port number is, as
well as allowing the user to diagnose any problem with conversion of
the host name into IP address.

Dale