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Re: [Xen-devel] ioemu: empty vnc passwd

To: Christoph Egger <Christoph.Egger@xxxxxxx>
Subject: Re: [Xen-devel] ioemu: empty vnc passwd
From: "Daniel P. Berrange" <berrange@xxxxxxxxxx>
Date: Wed, 23 Jan 2008 16:28:11 +0000
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, Samuel Thibault <samuel.thibault@xxxxxxxxxxxxx>
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On Wed, Jan 23, 2008 at 05:19:33PM +0100, Christoph Egger wrote:
> 
> If we do a debug build let us assume we are in a testing environment.
> There an empty vnc password is ok.
> If we don't make a debug build, let us assume we are in a production 
> environment where an empty vnc password is a security risk.

That logic is flawed. VNC may be configured to use TLS +x509 certificates
which provide real security. A VNC passwd is not really very credible 
security whether its zero or 8 chars in length. It shouldn't try to
second guess what an admin wants. 

VNC password authentication is turned on / off via the ',passwd' flag on
the -vnc command line to QEMU. If password auth is on, and a zero length 
string is found as a password, then all logins are completely disabled - 
the VNC password auth code will fail all logins. If passwd auth is off on 
the  command line, then any password stored in xenstore is irrelevant, no
matter what length it is.

Dan.
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