topic Re: Adding a flowSensor to an existing CSNA in Security Analytics

Adding a flowSensor to an existing CSNA

nastiakhon — Wed, 12 Aug 2026 13:58:49 GMT

Hello!

We already have a working CSNA with three nodes: Manager, DataNode, and Flowcollector. They've been running for almost a year. Now we've decided to add a FlowSensor, but adding it throws an error.

All our nodes are in the same subnet, including the new one. The versions match: VE version 7.5.3 build 20250624.2140. I'm also entering the correct "admin" password.

I should add that the current nodes have a certificate from our corporate CA, and the new FlowSensor has a self-signed one.

Please help me solve this problem.

Re: Adding a flowSensor to an existing CSNA

kegunner — Wed, 12 Aug 2026 14:29:33 GMT

Hi, I realise that you mentioned this in your message but when you reach this screen during the FTS process you are certain that you are using the correct manager details (IP and password) and not the password that was set earlier in the FTS process for the FS (which may be different to manager). You can check by logging into the manager with the admin password.

Re: Adding a flowSensor to an existing CSNA

nastiakhon — Wed, 12 Aug 2026 14:51:52 GMT

Yes, I'm entering the admin password specifically from Manager. I thought maybe I was typing it incorrectly, but then I checked and manually entered the password through the Manager GUI. And now I'm sure it's the right password.
I've tried it many times today. I even tried resetting the FS, but that didn't help either. After resetting the FS and going through all the steps again, after entering the data from Manager, I see a prompt:

I agree, and then I get message saying it can't register.

Re: Adding a flowSensor to an existing CSNA

nastiakhon — Thu, 13 Aug 2026 08:10:03 GMT

I tried downloading the certificate from flowSensor and importing it into Manager's TraustCert section. But that didn't help. Could the problem be something else? Is there a place I can check for the error preventing registration? Please help.

Re: Adding a flowSensor to an existing CSNA

kegunner — Thu, 13 Aug 2026 08:13:32 GMT

Hi, assuming there are no issues with basic connectivity to the manager or interface configuration on the new FS, I would recommend a TAC case in this instance.

Re: Adding a flowSensor to an existing CSNA

nastiakhon — Thu, 13 Aug 2026 08:18:09 GMT

Yes, I understand, but unfortunately, we don’t have the opportunity to contact TAC now.

Re: Adding a flowSensor to an existing CSNA

nastiakhon — Thu, 13 Aug 2026 10:04:34 GMT

Please tell me if it is possible to see the exact reason for the refusal somewhere.

Re: Adding a flowSensor to an existing CSNA

nastiakhon — Thu, 13 Aug 2026 12:47:14 GMT

I found the exact cause. I dumped the traffic from the Manager during the flow sensor registration, and it's clear that the flow sensor is sending messages to the manager that it doesn't recognize the certificate authority.

However, during registration, a question about trusting the Manager certificate still appears. It turns out we need to somehow upload our corporate root certificate to the flow sensor. Can anyone please tell me if this is possible? Or at least a rough plan?

Re: Adding a flowSensor to an existing CSNA

nastiakhon — Mon, 17 Aug 2026 09:55:53 GMT

I managed to solve the problem as follows. I deployed separate test virtual machines for Manager and FlowCollector. I attached FlowCollector to Manager. I attached my FlowSensor to Manager. I added corporate certificates through the Inventory menu. I detached my FlowSensor from the test Manager and attached it to the corporate Manager I have in Production. The addition was successful.