[3.4.8] net.tcp.service in simple check gives false positive result

[wapplersystems]

Hi, I have a problem with the simple check for HTTP and HTTPS Service. Both give me positive feedback, but I stopped the HTTP Server Apache.

zabbix-get -s 127.0.0.1 -k net.tcp.service[tcp,<ip>,80]
1

I checked the result with nmap:

PORT STATE SERVICE
80/tcp closed http

The port 80 ist open in the firewall, but the service is not running.

I'm expecting a negative result or do I have a understanding problem? Maybe the default method is not the correct method?

Just for sure I tested a real closed tcp port, like 81 and it gives a negative result.

Zabbix version 3.4.8

[sicko]

I believe the port is closed because there is nothing LISTENING on that port, and it should be considered as closed.

[wapplersystems]

I believe the port is closed because there is nothing LISTENING on that port, and it should be considered as closed.

If closed or not. I think the simple test should discover if the HTTP Server is running or not. In this case the Apache server was not running, but the test said it was available.

[wapplersystems]

The problem is, that the server is behind a "floating ip". This leads to a wrong measurement result of zabbix agent. Unfortunately, I do not know if you can solve the problem.

[Ilya Evseev]

The same problem with Zabbix-agent 4.0.15.

"net.tcp.service[http,hostname]" causes periodic trigger alerts while http://hostname is actually available (accessed by users and checked by external monitoring).