Remote access

Run PQViewer on the server holding your trajectory and use SSH forwarding to open it in your desktop browser. Keep the default 127.0.0.1 binding. Install PQViewer in the server’s Python environment.

From home or over a VPN

Connect to your institutional VPN first when it is required to reach the server. On your desktop, confirm that SSH access works:

ssh user@server

In that server terminal, start the viewer:

pqviewer /path/to/trajectory.xyz --no-open --port 8765

In a second terminal on your desktop, start the tunnel:

ssh -N -o ExitOnForwardFailure=yes \
  -L 127.0.0.1:8765:127.0.0.1:8765 user@server

Open http://127.0.0.1:8765 in your desktop browser. Replace user@server and the trajectory path with your own account, hostname, and server path. The same tunnel works on the institution’s network when SSH access is available.

Keep PQViewer and the SSH tunnel running. The tunnel terminal normally stays quiet; stop it with Ctrl+C when finished. ExitOnForwardFailure reports a local bind failure; it does not check whether PQViewer is running remotely.

A compute node behind a login node

If your site’s SSH policy permits access to an allocated compute node through the login node, start PQViewer on the compute node inside your allocation. On your desktop, use the login node as a jump host:

ssh -N -o ExitOnForwardFailure=yes -J user@login.cluster \
  -L 127.0.0.1:8765:127.0.0.1:8765 user@compute-node

The destination is the node running PQViewer. Use its actual allocated hostname and keep the allocation, viewer, and tunnel alive. If compute-node SSH is restricted, follow your site’s supported forwarding method.

A different desktop port

If desktop port 8765 is busy, forward port 18765 to the server’s port 8765:

ssh -N -o ExitOnForwardFailure=yes \
  -L 127.0.0.1:18765:127.0.0.1:8765 user@server

Open http://127.0.0.1:18765. The server command remains on port 8765.

Where data goes

Source files are read on the server, and PQAnalysis calculations run there. The browser interface, selected frame coordinates, and chart data are sent to your desktop through the encrypted SSH connection; the browser renders them. Files chosen with Open or drag-and-drop come from your desktop and are uploaded to the server. Frame, figure, and chart downloads are saved on your desktop.

Troubleshooting

  • SSH cannot connect: confirm that the VPN is connected and that the server’s hostname resolves and has a VPN route. Check ssh user@server before opening the tunnel; use the institution’s SSH hostname and account.

  • The local port is busy: use the alternate local port above, or stop the existing tunnel that owns it.

  • SSH connects but the page does not: confirm that PQViewer is still running on the SSH destination and that its port matches the tunnel’s remote port. For a compute node, check that the allocation is still active.

  • The VPN drops: reconnect it and start the tunnel again. Confirm that the server process and allocation are still running.

PQViewer has no HTTP authentication. SSH forwarding provides authenticated, encrypted access while the app remains on loopback; changing --host is not needed for this workflow.