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Eric Flumerfelt, 06/10/2014 12:18 PM

Conventions and Tools


The user interface environment to the DAQ system is hosted in VNC servers running on DAQ cluster computers at various sites. Users interact with these via VNC viewers hosted on control room desktops, and for experts, on their own desktop or laptop.

The NovaControlRoom package contains icons and scripts to automatically set up the needed ssh tunnels, and launch the VNC viewers. See docdb-8406 for a User's Guide.

VNC Servers

To set up VNC servers for the control room, see the VNC Setup How-To.

VNC Viewers

The command to start a viewer is including in the script launched by the desktop icons described in the User's Manual mentioned above, but the underlying command is of the form

 vncviewer -Fullscreen -Shared -passwd ~/.vnc/passwd :<NN> 

 -Fullscreen # starts in full screen mode
 -Shared # keeps other users from getting disconnected from the server when you connet
 NN # two-digit port number (relative to 5900) 


VNC Servers

In the current model (as of 2013-04-09), we run up to 4 VNC servers for each detector. In order to allow for different desktop environments on a single host machine, each VNC server on is run under a different account, using a dedicated port. We tend to use certain servers for particular functions, but this is subject to change.

Station Functions Account Port
1 Run Control
Message Logger
novacr01 5951
2 Event Display
Online Monitoring
APD Cooling GUI
novacr02 5952
3 Ganglia novacr03 5953

The servers for each of these is set up to occupy a 2x2 monitor grid, with total pixel count 3840x2160.

Two VNC servers run on the nova-daq-04 Control Room desktop in the Fermilab 12th floor control room, hosting webcam displays.

Note that VNC has a port base of 5900. However, in addition to the VNC connection itself, it also uses a port for the X11 connection 100 higher than the VNC port. Since general X11 connections use ports starting at 6010, and assuming less than 40 open connections is a safe bet, a good assumption for VNC port ranges that avoid conflicts with X11 would be 5900-5909 and 5950-5999.

The table below gives the VNC server host name used for each detector:

Detector Host
NDOS novadaq-ctrl-master
NDSBTest novadaq-nsbapd-master
FarDet novadaq-far-master-02
NearDet novadaq-near-master

ssh Tunnels

ssh tunnels are required to access the port for a VNC server on a remote host (e.g., for station 1 on NDOS) from a localhost (e.g., your laptop, or a control room desktop). Once launched, the tunnel can remain active indefinitely. The ssh command has the form

ssh -L <local_port>:localhost:<remote_port> -N -f -l <remote account> <remote host> 

The ssh tunnel is authenticated using a kerberos ticket on the localhost, usually for a special use (i.e., non-personal) principle. That principle must be in the k5login file for the remote account, and the remote host must be directly reachable from the localhost (i.e., the localhost must be in the domain.)

Since a single desktop will often have connections to the "same" display on multiple detectors, we need to have localhost port assignments vary by detector. The scheme in use by the NovaControlRoom package is

Station Detector Remote Port Local Port
1 NDOS 5951 5961
2 NDOS 5952 5962
3 NDOS 5953 5963
1 NDSBTest 5951 5971
2 NDSBTest 5952 5972
3 NDSBTest 5953 5973
1 FarDet 5951 5981
2 FarDet 5952 5982
3 FarDet 5953 5983
1 NearDet 5951 5991
2 NearDet 5952 5992
3 NearDet 5953 5993


On Windows, using RealVNC Viewer (renamed to vncviewer.exe), MIT Kerberos for Windows, and plink; the following batch file (FarDet1.bat) connects to the first screen of the Far Detector:
Start plink -ssh -L 5981:localhost:5981 <Principal>@<Gateway> "ssh -L 5981:localhost:5951 -N "
start vncviewer -Shared -passwd passwd localhost:81

passwd is a file with the MD5'd VNC viewer password, and <Gateway> is a machine connected to the Fermilab network accessible from the outside. Using the tables above, it is possible to connect to any detector/station combination.