How to fix a broken CAPTCHA in the login screen: EventLog Analyzer on Linux
Issue description
When you have enabled a CPATCHA on the login page of Linux using EventLog Analyzer's Logon Settings, you might face an issue where the CAPTCHA image seems to be broken. This article provides step-by-step instructions to fix the issue.
Possible causes
- The broken CAPTCHA image issue is often the result of either a browser cache problem or missing fonts required for rendering the CAPTCHA. Since Linux distributions typically do not include Microsoft fonts by default, you may need to install them manually.
Prerequisites
- Access to the EventLog Analyzer user interface.
- Access to the Linux server on which EventLog Analyzer is installed with root or similar permission to install a package.
Steps to follow
Step 1: Access the EventLog Analyzer user interface in an incognito/private browser window to check if the issue is related to the browser cache. If so, clear the browser cache to resolve the issue.
Step 2: If the issue persists, it is likely caused by missing fonts required for rendering. To install the necessary fonts, open the terminal and run the following commands:
Step 2: If the issue persists, it is likely caused by missing fonts required for rendering. To install the necessary fonts, open the terminal and run the following commands:
- sudo apt install fontconfig
- This command installs Fontconfig, a library and command-line utility used by Linux systems to manage and configure fonts. It enables font discovery, font substitution, and automatic fallback for missing fonts.
- sudo apt install ttf-mscorefonts-installer
- This installs a set of Microsoft TrueType core fonts, such as:
- Arial
- Verdana
- sudo fc-cache -f
- This command forces a refresh of the font cache used by Fontconfig.
- -f indicates "force" the rebuild, even if no changes are detected.
- This ensures that any newly installed fonts (like the Microsoft fonts) are detected and available to applications.
Step 3: Once the required libraries and fonts are installed, restart the Linux server once to have them applied.
Step 4: Reload the login page in a private/incognito browser window to verify.
Tips
- To verify if the fonts have been successfully installed, run the below command
fc-match Arial - This tries to find a font on your system that matches Arial. If the exact font isn't available, it returns the closest fallback (e.g., Liberation Sans, DejaVu Sans, etc.).
fc-match Verdana - This is same as the above command, which checks for Verdana.
How to reach support
- You can submit a ticket through our official support portal or you can reach out directly via email at eventlog-support@manageengine.com.
- In order for us to effectively help, include the below details so we can understand the issue better.
- A screenshot of the EventLog Analyzer license page.
- A screenshot of the login page showing the broken CAPTCHA issue captured from an incognito/private browser window.
- A screenshot of the Console tab from the browser's developer tools.
- To access it: Right-click on the login page, click Inspect, and go to the Console tab.
- A screenshot of the terminal output for the following commands:
fc-match Arial
fc-match Verdana - Product logs:
- EventLog Analyzer Serverout logs: <EventLog Analyzer Home>\logs\serverout_20xx-xx-xx.txt (Most recent file)
- EventLog Analyzer Catalina logs: <EventLog Analyzer Home>\logs\catalina_20xx-xx-xx.txt (Most recent file)