[CentOS] ssh -X versus -Y

Mon Jul 6 11:21:58 UTC 2015
Liam O'Toole <liam.p.otoole at gmail.com>

On 2015-07-05, Gordon Messmer
<gordon.messmer at gmail.com> wrote:
> On 07/05/2015 04:51 AM, Liam O'Toole wrote:
>> One practical difference I have seen is the improved performance of
>> -Y over -X. I have long attributed that to the relaxation of security
>> controls in the former case.
> When and how did you measure that?
> The -Y change was introduced in Fedora Core 3, in November 2004.  The
> default was changed to ForwardX11Trusted=yes just a month or two
> later.  I'm not sure -X and -Y ever behaved differently on Enterprise
> Linux or CentOS.
> At this point, I don't think it's even possible to set
> ForwardX11Trusted=no any more.  The X SECURITY extension was replaced
> with "X Access Control Extension" several years ago.

The perceived difference was a general impression on my part, and not
measured scientifically. Moreover, it was formed years ago, and on a
variety of Linux systems. I concede that it may well be obsolete.