: Often, a simple service restart or hardware reboot forces a re-authentication with the license servers. Verify DNS Settings : Ensure Kerio Control can resolve external hosts. Use the Google Public DNS (8.8.8.8) or Cloudflare DNS (1.1.1.1) as forwarders. Root Causes & Solutions 1. Expired Authorization Token (Zvelo)
If DNS fails, check your DNS settings in (try 8.8.8.8 as a secondary). If TCP connect fails, your upstream network (or ISP) is blocking these domains, or you have a routing issue.
You must restart Kerio Control after changing these DNS settings to clear the cached status. 2. Disable "Reliability Detection" (SSH)
Ensure that both the "Kerio Control" license and the "Web Filter" module are not expired. If your Software Maintenance Agreement (SMA) has lapsed, the categorization servers will refuse the connection from your appliance. : Often, a simple service restart or hardware
However, many administrators encounter a frustrating scenario: the Web Filter shows as or "categorization is disabled" in the Content Filter settings. When this happens, all web filtering rules based on categories cease to function, leaving your network exposed and policies unenforceable.
The system reveals its logic: Kerio Control sends automatic DNS queries to reach update servers. If these fail 10 times in a row within a single minute, the filter decides it can't be trusted and shuts down its categorization engine. This is often caused by: DNS Reliability
: If the filter stays "disabled" even after the network is fixed, the admin logs into the Kerio console via Root Causes & Solutions 1
Restart the entire Kerio Control engine if needed:
: Create a rule allowing traffic from the Firewall itself to: prod-update.kerio.com register.kerio.com control-update.kerio.com support.keriocontrol.gfi.com Verification Steps Navigate to Content Filter Applications and Web Categories and enter any website (e.g., google.com
Look for red text or an exclamation mark next to Categorization status . You must restart Kerio Control after changing these
💡 If the filter deactivates frequently, check your internet link speed. Slow links can trigger the "unreliable" flag, which the SSH fix above permanently ignores. Using Kerio Control Web Filter
As a result, your custom content filtering rules fail, applications lose their category context, and users might browse completely unrestricted or encounter complete network access timeouts.
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