Quick Tour

When you open nfsen-ng, you land on the Graphs tab — a live traffic chart for whatever’s currently being captured.

The navigation bar

Across the top: a home/reload icon, a dark-mode toggle (moon/sun), a reconnect spinner (only appears if your connection to the server drops — see below), and the five tabs: Graphs, Flows, Statistics, Sankey, and Settings. Whichever preset (source) you’re viewing shows in the top-left corner.

Switching tabs is instant — there’s no page reload, and whatever filters you had set on a tab are still there when you come back to it.

The shared control bar

Every data tab (Graphs, Flows, Statistics, Sankey) shares the same date range control at the top, plus a filter panel specific to that tab below it:

• Date range slider — drag either handle, or use the quick-select buttons (1 hour / 24 hours / Week / Month / Year) to jump to a common window. The ← / → buttons step back/forward by the current window’s length (e.g. clicking Week then → jumps forward exactly one week); ⇥ jumps to “now”.
• Custom duration — type a number, pick h/d/w, and click Apply for anything the presets don’t cover (e.g. “6 hours”).
• Sync now / Follow — on the Graphs tab specifically, Follow keeps the window pinned to “now” as new data arrives, so the chart scrolls automatically.

Changing the date range or any filter on the Graphs tab updates the chart immediately. Flows, Statistics, and Sankey are different — querying flow records runs the real nfdump tool, which costs real time and I/O, so those tabs only run a query when you click their Process data button. Nothing happens automatically until you do.

If you see a “Reconnecting…” banner

nfsen-ng pushes live updates to your browser over a persistent connection (Server-Sent Events). If that connection drops — your laptop slept, a proxy timed out, the server restarted — you’ll see a small spinner next to the dark-mode toggle and a banner at the top of the page. It reconnects automatically; you don’t need to reload, though a manual reload (the home/reload icon) never hurts if it seems stuck.

Where to go next

• The Dashboard — reading the traffic graph
• Browsing Flows — searching individual flow records
• Setting Up Alerts — get notified when traffic crosses a threshold