This sensor appears to allow using a port other than 443, but when I specify the correct port, it is timing out. Any ideas why?

We have an internal reverse proxy setup in kubernetes for docker and it uses port 30100 for HTTPS traffic. I can browse to the URL just fine from the PRTG probe, but the sensor times out. I don't get it.

Port field is set to: 30100

Virtual Host (SNI Domain) is set to: docker-horizons-saas-remote.docker.this.is.my.domain

Article Comments

Hi there,

Did you also configured the proxy in the setting "Proxy Settings for HTTP Sensors" in the settings of the device in PRTG?


Oct, 2020 - Permalink

Hello, I'm not sure I understand. This sensor was added to the local site's Probe Device and the certificate is hosted on a different device, where the reverse proxy lives (in Kubernetes/Docker). I'm not sure how the "Proxy Settings for HTTP Sensors" on the Probe device relates. Can you ELI5 this for me?


Oct, 2020 - Permalink

Hi Peter,

If the Sensor receives issue due to an proxy, you need to tell PRTG to use the proxy. This can be done in the mentioned setting. In this way, the Sensor knows to use the proxy to establish the connection. In addition, we recommend to create a own device for this Sensor. In this device, you can enter the URL of the webserver as IP/DNS setting.


Oct, 2020 - Permalink

I'm not sure if I'm misunderstanding you, or I'm not explaining correctly how our system is setup. Our company doesn't use a proxy server for traffic in general. The proxy in question is just in front of the server where docker templates are stored. The proxy device itself is what is hosting the SSL certificate, on port 30100. We are trying to detect the expiration date of the SSL certificate on the proxy. We are not trying to go THROUGH a proxy.

Am I making sense, or am I just being obtuse?


Oct, 2020 - Permalink

Hi Peter,

Thank you for the clarification, I understand the situation more clearly now. I checked the SSL Certificate Sensor in the latest PRTG version and could verify that the configured port is used. Which PRTG version do you use?


Oct, 2020 - Permalink