The moment that unsettles anyone setting up their own NSS machine
Anyone who does not forward log data through the machine-less path (Cloud NSS) but runs a dedicated NSS machine instead, for example because a separate SIEM needs to be fed in parallel or because log data must pass through the own network first, inevitably reaches this point: menu Logs, then Log Streaming, then Internet Log Streaming, then Deploy NSS Virtual Appliance. There you choose type and platform, the console calculates the recommended specification, and clicking Download is supposed to fetch the image for the virtual machine.
And then nothing appears to happen. No progress bar in the console, no noticeable message in the browser. This is exactly where the question arises: has the download stalled, or is it simply running silently?
The real problem is the missing feedback, not the download
The short answer: the download is running. The image transfers completely in the background, just without the feedback you would expect from an ordinary file download. The real problem is therefore not the download itself, but the silence during it.
That silence is costly because it invites action. Anyone who starts doubting themselves after a minute without visible movement clicks Download a second time, reloads the page, or cancels and starts over. Each of these reactions can trigger a second, parallel download of the same large file and end up extending the wait instead of shortening it.
The proof: developer tools and the Network tab
Anyone who wants to be sure something is actually running does not have to guess. It can be checked directly in the browser.
- Open the browser's developer tools: press F12, or right-click the page and choose "Inspect".
- In the panel that opens, select the "Network" tab; in Firefox the comparable panel is called "Network Monitor".
- If the tools were opened only after clicking Download: in Chrome and Edge, enable "Preserve log". Firefox offers a comparable setting. This keeps an already running request from disappearing from the list.
- In the list, look for the row with the largest, still-growing amount of transferred data. It shows no completed status yet, and the elapsed-time column keeps counting up.
- If that value keeps growing from one check to the next, the browser is actually transferring data. That is the download.
The exact column labels differ slightly between Chrome, Edge and Firefox, but the principle is the same everywhere: a single, long-running row with a growing size is the proof, not a percentage in the Zscaler console itself.
What to do
- Wait as long as the transferred amount in the Network tab keeps growing.
- Keep the tab open and do not reload the page while the transfer is running.
- Do not click Download a second time just because nothing visible happens in the console.
- Only restart the download once the transferred amount stays exactly the same across several checks.
Once the image has finished downloading, a separate step with its own pitfalls follows: creating the virtual machine itself, including choosing the correct generation and the two network adapters. That is already a topic of its own.
Where this article ends, the feed work begins
This article covers only the path up to the Healthy state in the Zscaler console. What comes after, setting up and checking the feeds, is a separate step. CentaurNexus has a dedicated area for that: NSS Feed Lens (nss_feed_manager) covers the NSS feeds configured in ZIA. It has nothing to do with the download described in this article.
Frequently asked questions
Why doesn't the NSS Virtual Appliance download show a progress bar?
Because the Zscaler console triggers the download through its own web interface rather than a plain link. As a result, the browser often does not show its usual progress indicator, even though the file transfers completely in the background. The ongoing transfer becomes visible in the Network tab of the developer tools.
How long does the NSS Virtual Appliance download take?
That depends on your own internet connection; no reliable blanket duration can be given. As long as the transferred amount keeps growing in the Network tab, the download is still running.
I already clicked Download several times out of impatience. What now?
No need to worry. Open the Network tab and check how many large transfers are actually running. Let them finish undisturbed before starting anything new.
See the feed area in the demo
Once your machine is up, the feed work begins. The demo launcher shows NSS Feed Lens with prepared sample data.
Open demo launcher