noVNC

QuickBox adds iptables rules to accept only localhost traffic on the VNC daemon port and drop other traffic. Access is intended through the nginx paths instead of direct VNC port access.

noVNC uses only the first 8 characters of the password, so anything past the eighth character is ignored when you connect. Saving also restarts noVNC and disconnects any active desktop session, so reconnect with the new password afterward.

This happens when the apt-listbugs package is present on the server. While noVNC installs firefox-esr and the Xfce/X11 packages, apt-listbugs intercepts the transaction, prints any known bug reports for those packages, and waits for you to confirm. If nothing answers the prompt, the apt run exits non-zero (commonly error code 10) and the noVNC install reports a dependency failure.

1. Remove the interactive bug-prompt tool so apt can complete non-interactively:

   apt-get -y purge apt-listbugs

2. Refresh the package lists and finish the pending package work:

   apt-get update
   apt-get -y --fix-broken install

3. Re-run the install:

   qb install novnc -u username

If you prefer to keep apt-listbugs, you can instead pre-install the dependency set in a session where you can answer the prompt, then run qb install novnc.

The Xfce + X server + firefox-esr dependency set requires up-to-date package lists. A stale or partially-updated apt cache can leave the install unable to resolve firefox-esr, tightvncserver, or the xserver-xorg packages.

Fix: refresh apt and clear any broken state, then reinstall:

apt-get update
apt-get -y --fix-broken install
qb reinstall novnc -u username

Checks: Confirm vnc@username.service is running and /home/username/.vnc/xstartup exists and is executable. The xstartup script launches the Xfce session — if the service is stopped, or xstartup is missing or not executable, the VNC server never brings a desktop up.

systemctl status vnc@username.service
ls -l /home/username/.vnc/xstartup

A grey stippled background with nothing on it except an X mouse cursor is different from the case above: the VNC service is running, xstartup exists and is executable, but the Xfce desktop session did not paint. The X server came up; the desktop on top of it did not.

Read the session log to see why the desktop stopped. The log is named after the server hostname and display :1:

cat ~/.vnc/$(hostname):1.log

Confirm the Xfce packages are intact:

apt-get -y --fix-broken install

Fix (recommended): update noVNC so it re-applies QuickBox’s current session startup, which launches the Xfce desktop on its own D-Bus session so it paints reliably:

qb update novnc -u username

If updating does not clear it, reinstall with qb reinstall novnc -u username. Both re-apply the hardened session startup and neither resets your noVNC password. Hand-editing /home/username/.vnc/xstartup is only a fallback if you cannot update or reinstall.

This most often shows up after installing another remote-desktop app such as X2Go on the same server — see Running noVNC alongside X2Go below.

Checks: Confirm novnc@username.service (the websockify proxy) is active and that /etc/nginx/conf.d/username.vnc.conf points to the assigned web port. The websockify proxy bridges the browser WebSocket to the VNC server — if it is stopped, the page loads but the connection is refused.

systemctl status novnc@username.service
systemctl restart novnc@username.service

This is expected. QuickBox adds iptables rules that accept VNC daemon-port traffic only from localhost and drop everything else. Connect through the browser path /username/vnc (which goes through the websockify proxy and nginx), not by pointing a desktop VNC viewer at the daemon port.

The /username/vnc route is protected by nginx HTTP Basic auth using /etc/htpasswd.d/htpasswd.username. A second password prompt comes from the VNC server itself — a dedicated noVNC password that defaults to your QuickBox account password at install. If Basic auth keeps failing, confirm the htpasswd file exists for your user. If the VNC password is rejected, set a new one from the Dashboard (App Dashboard → the noVNC row → API & Secrets) or with qb user vncpasswd -u username — see Change your noVNC password. A reinstall does not reset this password, since it is stored separately and survives reinstall.

noVNC and X2Go coexist fine on one server. X2Go stands up its own per-user D-Bus session, and on an older noVNC install that stray session bus could attach the noVNC desktop to the wrong bus and leave it blank — the grey-screen symptom above. QuickBox’s current session startup launches noVNC’s Xfce desktop on its own isolated D-Bus, so the two run side by side without interfering.

If your noVNC desktop went blank after installing X2Go, update (or reinstall) noVNC to apply the fix — X2Go itself needs no change:

qb update novnc -u username