Cannot open display while running X Apps as another user - linux

I am currently using X11RDP to connect to a RHEL 6.5 endpoint, as root user. All X apps work fine, and directed properly to the right display (say 11.0).
Now if I switch to another user (su - user1), then I try to open any X app (say xterm) it will be unable to open the display (even though it is also 11.0).
I do not believe the problem to be with xauth (magic cookies, etc), or the DISPLAY environment variable not being set correctly, or allowing connection with xhost +; but rather something with XRDP.
Any help would be appreciated.

The solution to my problem was actually in how x11rdp was starting.
It starts the x server with -nolisten tcp.
If that part is commented out in /etc/xrdp/sesman.ini for x11rdp then the problems described above will be gone.
Hope this helps other people experiencing the same problems.

Related

Ubuntu 20.04 x11vnc blank (not black) screen after session login

I have a remote headless server without a monitor attached with SSH access.
From what I found out the hard way, the default install does not support VNC (using vino) without a monitor attached.
Tried several things to get this working this without success.
I followed this guide on setting up x11vnc and lightdm: https://www.crazy-logic.co.uk/projects/computing/how-to-install-x11vnc-vnc-server-as-a-service-on-ubuntu-20-04-for-remote-access-or-screen-sharing
I then also tried to install xubuntu-desktop, which did not help.
The issue is:
VNC asks for password and connects. All good.
I see the session login window (with the panel at the top), everything looks ok. All good.
screenshot1
After login I only see a blank screen. Nothing responds. Right click on the desktop does not open a context menu. Not good.
screenshot2
Expected would be to see the desktop, panels, menus...etc.
How would one solve this? And what exactly is happening here. The session logs show everything is ok, no errors. But the computer is unresponsive on VNC, only the background is visible.
Note: I do not have physical access to this server. A solution via SSH would be best.

How to fix samba share connection problems with secpol.msc?

I had one client who could not connect to a samba share giving the error that the credentials where wrong while I was sure they where not.
This happened suddenly on a laptop with Windows 10 while other clients with Windows 10, Windows 7 and Ubuntu etc. all where able to connect.
At first I was suspecting the problem beeing a change in the hash or key for the share - and maybe it really was because Putty was saying so when I tried to SSH into the server.
But I could not find any saved connection to delete with net use.
The solution was to change a setting in secpol.msc which is accessible as administrator via the search even in Windows 10 Home.
I had to set LAN-Manager-Authenticationlevel to just send NTLMv2.
You will find this setting under Security settings -> local -> Security options -> Network Security: LAN-Manager-Authenticationlevel.
(I translated this from German. Feel free to edit with nativ english wording.)

Chrome OS: how to enable direct SFTP access in the Files app / Pixelbook Review

An article on Chrome OS that I read here:
https://medium.com/#JamesCridland/review-five-months-with-a-chromebook-for-web-development-writing-and-more-8adf36b4a061
says:
"Update: Above, I mention that I use SSH and vi to do my programming work. And I did. Except I don’t any more. It turns out that one of the newer updates added direct SFTP access into the Files app (the equivalent of Explorer or Finder), so that my development box appears simply as another drive on my Chromebook. And Caret is an excellent programmer’s editor. So now I have a proper programmer’s editor (as well as the SSH terminal I need to put those changes live)."
Ok. But, when I go into Chrome OS's files app, the apparent way 'mount' my equiv of his
'development box' is via 'add new services', which is launching a webstore-app named 'SFTP' (whose icon is a blue folder outline with "SFTP" on it). i,e.:
https://chrome.google.com/webstore/detail/sftp-file-system/gbheifiifcfekkamhepkeogobihicgmn?hl=en
(My equiv of his 'development box' I'm assuming to be my web-server at bluehost.com, where I currently use Firefox's FireFTP extension, on Win-10.)
I can't get this 3-stars webstore 'SFTP' app (authored by someone from Japan) to authenticate me into my bluehost acc't. So, now I'm wondering whether
this 'SFTP' app is even the right thing to have installed, due to all the one- and two-star showstopper reviews. One typical review by a guy named Tim says:
"It's a nice try, but I really wish someone who knows what they're doing would make this service. It looks like it works but if you drill down more than a few folders deep on the remote filesystem, operations slow to a crawl."
Similarly, the two clients ('sFTP client' and 'sFTP client Lite) also have such low ratings, that my gut says that Google has failed to deliver a robust web-developer infrastructure.
Come on Google...you need to implement this stuff under your own logo.
Am I missing something???
Probably should advertise this functionality better :), but the Secure Shell App supports mounting via SFTP so it will appear in the Files app.
Steps to use:
Install Secure Shell Chrome extension.
Launch the extension (look for it in the bar to the right of the omnibox/browser URL bar -- it'll have a black terminal icon).
Enter the connection details to create a new profile.
Give it a description like "user#foo.com".
Instead of clicking "Connect" in the bottom right, click "Mount".
Authenticate with the server (keys/pass/whatever).
Once it finishes, it'll now be visible in the Files app.
If you suspend/resume the system or otherwise logout/reboot, you'll need to relaunch Secure Shell, select the saved profile, and then click "Mount" again. We probably should make this a bit smoother, but that's how it works currently.
No, not an answer yet...just more wishlist stuff:
Ok, more recent info about the Firefox browser's "FireFTP" addon:
It no longer works on the (new) std Firefox browser, as of a couple of
weeks ago when version 57.0 was released. (No biggie tho...a goggle revealed
a new-to-me browser called 'Waterfox' and it nicely supports FireFTP and the
other addons that Firefox dropped support for.)
So a bit more research yielded only yet more 'mumble-mode' confusion: it revealed that FireFTP is open source...located here:
https://github.com/mimecuvalo/fireftp
(So I submitted a new 'issue' there and asked about porting it to Chrome.)
I'm desperate, and recently test-drove Google's new Pixelbook.
(Sigh...nothing inspirational came of that...I give it one-thumb-down rating.
Here's my notes from that experience:
------------ Review notes of Pixelbook: ----------------------
Google didn’t think to include a USB-C to USB-A adapter. (A $2 item. e.g.)
https://www.amazon.com/Remax-USB3-1-Female-Adapter-Silver/dp/B01MCSRSKN/
That was my 'showstopper'...like a few other reviewers said...it's not well
thought out / matured. To me it feels more like a gimmick, than a product.
At a minimum, it rates my newest hashtag: #NRFPT (not ready for prime time).
I found no obvious way to disable the touchpad, when using a mouse.
In fact, no other reviewers expressed interest in using a mouse. (???)
Lastly, my favorite kind of Android apps are 'widgets', and I see no signs
that it has occurred to Google to allow Chrome-OS's desktop/background to
host any widgets.
Ok, I'm still in mumble-mode...and still in search of a FTP/SFTP GUI client for
the Chrome browser / Chrome-OS that is the quality of FireFTP.
Enable Linux(beta) on your chromebook. Then you can do whatever you want like on others linux machine.
A simple sftp connection command
sftp [user#]host
Enable linux and mount with sshfs
sudo apt install sshfs
then
sshfs -o reconnect,ServerAliveInterval=15,ServerAliveCountMax=3 user#xxx.xxx.xxx.xxx:/remotedir localdir
or with key auth
sshfs -o reconnect,ServerAliveInterval=15,ServerAliveCountMax=3,IdentityFile=~/.ssh/id_rsa user#xxx.xxx.xxx.xxx:/remotedir localdir
These will reconnect after resuming from sleep

Error: Can't open display:

I am working my way through 'The linux command line' (http://linuxcommand.org/tlcl.php) . Since I don't have a local linux environment and I have to work in windows , I am telnetting into an Ubuntu 14.4 LTS instance on EC2 , with putty. On page 114 , when I run the xlogo command I get:
ubuntu#ip-172-31-22-65:~$ xlogo
Error: Can't open display:
How can I get this working?
xlogo will try to access the current Xserver to display a logo. If you're telneting to a box, you will not have an X server available, which is what that "can't open display" message is saying. It's trying to look at your DISPLAY environment variable to use that to show the logo on, but you don't have a display to use, and thus have nothing in your DISPLAY variable.
You will need access to an X server somewhere to do that step. One option would be to install cygwin on your Windows machine. Then you wouldn't need the remote linux box for most steps I imagine, because you could just use your local cygwin environment. Even if you want to use the remote box still, if you use cygwin and launch an xterm with it, you could ssh -X <host> and that will export your DISPLAY to that remote machine so it can display back on your windows machine.
As I mentioned in the comment under Eric Renouf answer, I am working thru the same book. That part of the book have some testing of creating users, groups, shifting users, group permissions etc. I found that I needed to log the same user out quite some times. The last time logging that user out, I got a message saying xlogo is terminatet, like it was hanging on that user?
After everyone was logged out, I logged in as sudo and everything worked again.

ssh and window ids

I have a project to do in school which is baffeling me... I am SSHing into a Solaris computer in the computer lab from my own Debian box via
ssh -Y name#***.cs.<school>
I can get in just fine, and the X11 seems to be working also. However, this peticular project requires us to find the window id of a netscape window via xwininfo and use this information in the following command
netscape -id 0xa00029 -remote 'openFile(/path/to/html/file)'
Now, if this netscape is the only window I have open (other than xterm), the preceding command works just fine. However, if I have any other iceweasel windows open (regardless of the order in which I opened netscape/iceweasel) the command will forward to my iceweasel despite the facts that I'm running the command in my SSH session and the two windows have very different window ids.
All of this eventually has to go into a C program, but I can't even get it to work reliably manually!
Any ideas?
P.S. I just saw this that may help. When I SSHed via Cygwin/X using the same command, I get this error
Warning: No xauth data; using fake authentication data for X11 forwarding.
Not sure if this is important as I can still use X11 (aparently) perfectly.
Thanks.
P.P.S the -id switch is documented in the netscape man pages:
-id window-id
Identifies an X window to receive -remote commands. If
you do not specify a window, the first window found is
used.
When you use ssh -Y, you're requesting that remote clients be forwarded to your local X server, with full permissions. The Netscape/Mozilla/Firefox/Iceweasel/Etc. remote protocol runs through the X server, so it'll be forwarded too.
http://www.mozilla.org/unix/remote.html documents the protocol, and mentions nothing about -id. Nor does a very quick look at the source (e.g., http://mxr.mozilla.org/seamonkey/source/widget/src/xremoteclient/XRemoteClient.cpp#202) look promising for there being an -id option.
I sat down to an actual machine to perform the same tests, and they all fail there too... I would open 2 netscape windows and try to direct the command to one at a time. The most recently opened one would work properly, but any command directed to the other one would be forwarded to the same window, so at this point I am convinced that the problem lies in the command being not properly implemented and/or everything on that system being really, really old.
if I have any other iceweasel windows
open (regardless of the order in which
I opened netscape/iceweasel) the
command will forward to my iceweasel
despite the facts that I'm running the
command in my SSH session and the two
windows have very different window ids
Iceweasel is coded that way. It tries to have only a single process run for all open windows for that user.
Use the -no-remote command line option to avoid it. See http://kb.mozillazine.org/Command_line_arguments

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