New Question
PRTG Network Monitor

Intuitive to Use.
Easy to manage.

300.000 administrators have chosen PRTG to monitor their network. Find out how you can reduce cost, increase QoS and ease planning, as well.

Download >>


What is this?

This knowledgebase contains questions and answers about PRTG Network Monitor and network monitoring in general. You are invited to get involved by asking and answering questions!

Learn more


Top Tags

View all Tags

http sensor unable to find string



Your Vote:



We have an http sensor that is unable to find any keyword we enter on the settings page for the sensor.

Using a simple PHP script, we have no problem finding the desired keyword. The page is

The keyword being sought is Information Using a PhP string search I get this result:

File Length is: 425297 Found Information at 406024

I deleted and recreated the sensor by cloning a similar sensor that is working for a different web site on the same server. This site still has the same problem with the cloned sensor.

http-sensor keyword not-found

Created on Jun 27, 2018 2:49:03 PM by  jdelaney (0) 1

1 Reply



Your Vote:




Thank you for the KB-Post. I could reproduce the issue here, and to debug it, I enabled the "Store latest HTML result" on the sensor. In the resulting sensor log ("Result of Sensor xxxxx-A.txt") the HTML was stored which the sensor sees, and it's something entirely different, than what you get when visiting the page with a proper browser. Does the page differentiate in any way there? So that it redirects any requests from unknown client types to a different page?

best regards

Created on Jun 28, 2018 1:06:20 PM by  Torsten Lindner [Paessler Support]

Please log in or register to enter your reply.

Disclaimer: The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.