This article describes how to use the HAR log to further check which destination address to focus on when encountering a website access issue.
Table of Contents
Scope
FortiGate.
Solution
Diagram
Sample Scenario
This capture was taken in a lab environment just to show how to maximize the HAR log tool to see which IP to focus on in website access issues.
Test machine (IP: 10.118.4.202) is experiencing slowness when accessing CoinMarketCap, while other websites (e.g., Google, YouTube) are working fine. Here is the approach to diagnose and resolve this issue:
Open Chrome Developer Tools:
Navigate to the Network tab:
Ensure the Domain column is visible:
Check the HAR log for unsuccessful traffic when the issue occurs.
Analysis
From the HAR log, a JavaScript file from the domain cdn.cookielaw.org failed to load:
Ping the domain cdn.cookielaw.org to obtain its IP address:
Filter this IP address in FortiGate to observe how it is being handled:
Resolution
Step 1: In the lab FortiGate, filtering logs using the IP [104.19.177.52] showed that traffic to this IP was being blocked.
Step 2: Creat a policy in FortiGate to allow traffic to this IP.
Step 3: After implementing the policy, CoinMarketCap started working without any issues.