vncviewer fails to connect to vncserver

[zenny]

Hi,

This is in pursuant to @dcommander suggestion at https://github.com/VirtualGL/virtualgl/issues/11#issuecomment-161181948

Platform: TurboVNC v2.0.1-20151105 in Ubuntu 14.04 Trusty.

I started a vncserver (official .deb from sf.net installed to /opt/TurboVNC/ folder by default) in reference to https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-vnc-on-ubuntu-14-04

$ sudo service vncserver start
 * Starting vncserver for user 'zenny' on localhost:2...                                                            
Desktop 'TurboVNC: MACHINE-GA-970A-D3:2 (zenny)' started on display MACHINE-GA-970A-D3:2

Starting applications specified in /home/zenny/.vnc/xstartup.turbovnc
Log file is /home/zenny/.vnc/MACHINE-GA-970A-D3:2.log

But when I try to connect with ssh it says,

channel_setup_fwd_listener: cannot listen to port: 5902
Could not request local forwarding.

I checked /etc/ssh/sshd_config`to check whether X11 forwarding was disabled, but was not the case.

$ grep Forwarding /etc/ssh/sshd_config
X11Forwarding yes

Obviously, vncviewer died with:

$ /opt/TurboVNC/bin/vncviewer 
libjawt.so path: /usr/lib/jvm/java-7-openjdk-amd64/jre/lib/amd64
Could not connect: Connection refused

'netstat -plant | grep Xvnc' gives Xvnc instant running in port 5902

tcp        0      0 0.0.0.0:5902            0.0.0.0:*               LISTEN      9911/Xvnc       
tcp        0      0 0.0.0.0:6002            0.0.0.0:*               LISTEN      9911/Xvnc              
tcp        0      0 0.0.0.0:5802            0.0.0.0:*               LISTEN      9911/Xvnc       
tcp6       0      0 :::6002                 :::*                    LISTEN      9911/Xvnc  

Appreciate any hints on the right way to use TurboVNC! Thanks!

[dcommander]

• Those instructions are not ours. They mention TightVNC, not TurboVNC. For whatever reason, Ubuntu is still shipping TightVNC 1.3.x, even though that project is no longer maintained. Please use the TurboVNC User's Guide for the version you are trying to install: http://www.turbovnc.org/Documentation/Documentation. It may be that you can make the instructions at digitalocean.com work with TurboVNC, but I cannot support those instructions, since I didn't write them, and they aren't even meant to be used with TurboVNC. Ubuntu won't support them, either, so if you choose to use those instructions, you're on your own.
• The "X11Forwarding" setting in sshd_config has nothing to do with this. That setting specifies whether you can forward X11 traffic over SSH (VNC is a virtual X server, but it doesn't use the X11 protocol for the remote connection.) Instead, you need to verify that "AllowTCPForwarding" is set to yes.
• Unless you have opened up the appropriate ports in your firewall, you will have to tunnel the RFB connection over SSH, as you seem to be trying to do. However, you are leaving out one important step, which is specifying tunneling on the client end: /opt/TurboVNC/bin/vncviewer -tunnel MACHINE-GA-970A-D3:2 (you can also start vncviewer without arguments and enable tunneling in the Options dialog, under "Security".)

[zenny]

@dcommander Thanks a zillion for very useful inputs here to prove that how simple TurboVNC is as well as at https://github.com/VirtualGL/virtualgl/issues/11#issuecomment-161392904. The documentation you pointed to, and --help pages were extremely enlightening.

In the meantime, I am trying NOT to scale down the server's geometry while downsizing only the client's (vncviewer's) to half (1/2), but that does not seem possible with what I understood and executed as of below:

$ /opt/TurboVNC/bin/vncserver -geometry 3840x2160 -depth 32 -xstartup 'vglrun -c proxy libreoffice'

$ /opt/TurboVNC/bin/vncviewer MACHINE-GA-970A-D3:2 -DesktopSize=Server

Once I get connected, virtual x server's resolution is reportedly 1916x1022 instead of the geometry I assigned (3840x2160) above.

Did I miss some parameters? Thanks again.

PS: The second issue that I am having is that the icons of libreoffice app is not being rendered clearly (greyed out) as seen in the attached screenshot at http://picpaste.com/SKX3BlSH.png. Cannot figure out whether it is a bug or a feature?!

[dcommander]

Several comments:

• -depth 32 is unnecessary with TurboVNC (that's already the default.)
• -c proxy is unnecessary with vglrun in a TurboVNC environment (VirtualGL will automatically detect that it's running in an X proxy environment.)
• Generally it isn't recommended to run a windowed application like OpenOffice in TurboVNC without a window manager. The approach you took above, passing a single application using the -xstartup parameter, would work with a single-window, full-screen application, but the results with windowed applications will be unpredictable at best. VNC is a fundamentally different type of solution than xpra, in the sense that xpra's server and protocol are designed to handle remote window management but VNC's server and protocol aren't. The VNC session is essentially behaving as a remote virtual desktop.
• Regarding the unwanted resizing of the remote desktop, I have observed with some WM's that the WM will remember the last desktop size that was used with it (for instance, from a local session) and will attempt to resize the desktop to that size the next time the WM starts. But since you aren't using a WM, I have no explanation.
• It isn't necessary to use vglrun (VirtualGL) unless the application uses OpenGL.