url_response does not send alarm when it has no physical access to url

Products

• DX Unified Infrastructure Management (Nimsoft / UIM)
• CA Unified Infrastructure Management On-Premise (Nimsoft / UIM)
• CA Unified Infrastructure Management SaaS (Nimsoft / UIM)

Issue/Introduction

Url_response probe is configured to monitor a set of url's and seems to be working however when servers' physical access to the url's is blocked the probe does not raise an alarm.

Probe log shows:

Feb  4 15:02:39:823 [6836] url_response: Using InternetConnect / HttpOpenRequest / HttpSendRequest to fetch https://www.example.com/
Feb  4 15:02:39:824 [6836] url_response: HttpQueryInfo returns 0 - Unknown error: 0
Feb  4 15:02:39:824 [6836] url_response: [test_url] debug - MyGet (https://www.example.com/) returns 0
Feb  4 15:02:39:824 [6836] url_response: [test_url] used 0 ms, 0 + 0 bytes, 0 bytes read
Feb  4 15:02:39:824 [6836] url_response: SREPLY: status = 0(OK) ->###.###.###.###/55657

Environment

Release: 8.51

Cause

• The probe uses the HttpQueryInfo function when configured to use Windows NT Authentication as the authentication method.
• The monitored url is returning the 0 return code to the HttpQueryInfo function
• The probe interprets the 0 return code as success and thus no alarm is raised.

Resolution

• Changing the probes configuration to Basic Authentication means the probe will use curl instead and allows the probe to successfully detect the URL status.