[CentOS] Failed to start new browser session: Error while launching browser on session null

Nico Kadel-Garcia nkadel at gmail.com
Wed Mar 30 12:06:19 UTC 2011

On Wed, Mar 30, 2011 at 7:39 AM, ken <gebser at mousecar.com> wrote:
> On 03/29/2011 05:45 AM John Hodrien wrote:
>> On Mon, 28 Mar 2011, ken wrote:
>>> Like the error says, you need to specify the display.  I.e., on the
>>> remote machine you must set the environmental variable "DISPLAY"...
>>> something like
>>> (export DISPLAY= & firefox)
>>> Though this may work, this may well reveal another, different error, one
>>> having to do generally with permissions.  But we'll take them one at a time.
>> Do *not* follow this advice.  It's bad practice, insecure, and actually more
>> work than being secure, and more likely not to work.  Plenty of X servers are
>> configured to not listen on your network interface for example.
>> ssh -X / -Y is your friend, as others have suggested.
>> jh
> John,
> Whether or not it's "more work" is highly subjective.  And it's not
> inherently insecure; people often *make* it insecure by lazily setting
> permissions to allow *any* server to have access.  Even ssh can be
> insecure if it's not configured properly.

The lack of encryption is automatically insecure, and anyone who can
start an X program with the 'DISPLAY' set on the remote server can
access the X session. I've used this to run 'xroach' on people's
systems who refused to secure their X sessions properly. I actually
got in trouble for all the screaming.

It's also hideous practice to hardcode that X server in the .bashrc,
because logins from home or another system will push the X sessions to
that hardcoded X server. Really, it's a bad practice from 20 years ago
by people who didn't understand X and who just wanted things to work
now. It should *never* be replicated these days, except under the most
deranged of circumstances (such as wanting everybody's X programs to
pop up on a single, shared X server for public display.)

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