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Why FortiGuard Web Filter is Blocking Everything? How to Fix It

This article outlines fundamental guidance and procedures to adhere to when initiating the troubleshooting process and addressing prevalent FortiGuard problems.

FortiGuard Web Filtering is a powerful tool used by organizations to manage internet access and protect users from harmful content. However, there are instances where it may block all or most websites, leading to frustration among users. Below are the common reasons why this happens and step-by-step solutions to fix the issue.

1. Valid Subscription Status

Reason: FortiGuard Web Filtering requires an active subscription. If the subscription has expired, the service will stop functioning correctly, resulting in a blanket block on all websites.

Solution:

  • Check Subscription Status: Log into your Fortinet firewall and verify that your FortiGuard subscription is active.
  • Renew Subscription: If it has expired, contact Fortinet Customer Service to renew your subscription.

2. Incorrect Firewall Policy Configuration

Reason: The firewall policy may not be configured correctly to allow traffic through or might have overly restrictive settings.

Solution:

  • Review Firewall Policies:
    • Navigate to Policy & Objects > Firewall Policy.
    • Ensure that at least one policy allows web traffic (HTTP/HTTPS) and has a valid Web Filter profile attached.
  • Create or Modify Policies:
    • If no policies exist, create a new one allowing traffic from your internal network to the WAN.
    • Ensure that the Web Filter profile is set to allow desired categories while blocking unwanted ones.

3. DNS Configuration Issues

Reason: If the DNS settings are misconfigured, clients may not be able to resolve domain names properly, leading them to receive error messages instead of accessing websites.

Solution:

  • Set Up DNS Correctly:
    • Go to Network > DNS Servers in your Fortinet interface.
    • Enable DNS service on the internal interface and configure it to use FortiGuard DNS servers for better reliability.
  • Client Configuration:
    • Ensure client devices are using the Fortigate’s IP address as their DNS server (e.g., if your LAN IP is 192.168.2.5, set this as the DNS on client devices).

4. SSL Inspection Issues

Reason: Websites using HTTPS may not load properly if SSL inspection is not configured correctly, causing blocks due to certificate errors.

Solution:

  • Enable SSL Inspection:
    • Go to Security Profiles > SSL/SSH Inspection.
    • Ensure you have an SSL inspection profile applied in your firewall policy.
  • Install CA Certificate on Clients:
    • Download the CA certificate from the Fortigate and install it on client machines’ Trusted Root Certificates Store for proper SSL handling.

5. Port Blocking by ISP or Network Configuration

Reason: Some ISPs block non-standard ports used by FortiGuard services (like port 8888), which can lead to connectivity issues with web filtering services.

Solution:

  • Change Ports Used for Web Filtering:
    • In System > FortiGuard, change the port from 8888 (default) to 53 if you suspect port blocking.
  • Test Connectivity:
    • Use CLI commands like exec ping service.fortiguard.net and check if you can reach FortiGuard servers successfully.

6. Misconfigured Replacement Messages

Reason: Users may see generic error pages instead of customized replacement messages when accessing blocked sites due to misconfiguration in replacement message settings.

Solution:

  • Configure Replacement Messages Properly:
    • Go to Security Profiles > Web Filter.
    • Under Replacement Messages, ensure that appropriate custom messages are set up for blocked content instead of default error pages.

By following these steps systematically, you should be able to diagnose why FortiGuard Web Filtering is blocking everything and implement fixes accordingly.

Authoritative Sources Used

  1. Fortinet Documentation – Official documentation provides detailed guidance on configuring and troubleshooting FortiGate firewalls and related services.
  2. Fortinet Knowledge Base Articles – A collection of articles addressing common issues faced by users of Fortinet products, including troubleshooting tips for web filtering problems.
  3. Fortinet Community Forums – User-contributed discussions that offer insights into real-world problems and solutions regarding FortiGuard configurations and issues encountered by other administrators.