[chewcw]

Summary

Fix the VNC connection failure ("VNC server closed the connection") when Remmina connects to the Docker image.

Changes

supervisord.conf (novnc/websockify)

• Removed --cert=/home/ubuntu/novnc.pem . The file and /home/ubuntu/ user don't exist in the container. It was unused.
• Fixed websockify command syntax. websockify 0.10.0 does not support --target-host or --target-port . It uses positional args.
• Before: websockify --web=... --cert=... 6080 localhost:5900
• After: websockify --web=... localhost:6080 localhost:5900

supervisord.conf (server/client binary paths)

• The CMakeLists.txt sets config-specific output dirs only for multi-config generators (VS/Xcode). On Linux with Makefiles and CMAKE_BUILD_TYPE , binaries land directly in CMAKE_BINARY_DIR ( /app/bin/ ).
• Fixed the binary names to what CMake actually produces: mbserver / mbclient , not server / client .
• Paths changed from /app/bin/Release/... to /app/bin/mbserver and /app/bin/mbclient .

Dockerfile (EXPOSE)

• Added EXPOSE 5900 so Remmina can reach x11vnc directly. Before this, only 6080 was exposed. That port is the websockify WebSocket proxy. Remmina sends raw VNC protocol to it and gets "VNC server closed the connection".

Validation

• docker build succeeds. Image tagged chewcw/modbus-tools .
• All 6 supervisord programs (Xvfb, x11vnc, fluxbox, novnc, server, client) enter RUNNING state.
• x11vnc on host port 5900 responds with RFB 003.008 ServerInit. Remmina can connect directly to localhost:5900 .
• noVNC web UI on port 6080 serves /vnc.html (HTTP 200).