Software⏱️ 3 min read📅 2026-06-11

How to Fix: Squid logs show "TCP_DENIED/407" error

Squid caching server logs error TCP_DENIED/407 fix

Quick Answer: Check Squid configuration for proxy settings and ensure that the 'Deny' directive is not set to block specific domains or IP addresses.

📋 Table of Contents

  1. 🔍 Why This Happens
  2. 🔧 Proven Troubleshooting Steps
  3. 💡 Conclusion

The 'TCP Denied/407' error occurs when Squid, an HTTP proxy server, blocks requests to certain websites due to authentication issues. This error affects users who rely on Squid for internet access and are unable to connect to websites that require authentication.

This issue can be frustrating as it prevents users from accessing their desired content, such as downloading software or browsing websites. In this guide, we will walk you through the root causes of this error and provide two methods to resolve the issue.

🔍 Why This Happens

  • The primary reason for 'TCP Denied/407' errors in Squid is that the proxy server is configured to block requests from unknown or unauthorized clients. This can happen when Squid is not properly configured or if there are issues with the authentication settings.
  • An alternative cause could be a misconfigured Squid configuration file, such as the squid.conf file, which may contain incorrect or missing authentication settings.

🔧 Proven Troubleshooting Steps

Configure Squid to allow HTTP requests from authenticated clients

  1. Step 1: Step 1: Open the squid.conf file in a text editor and navigate to the auth parameter. This setting controls whether Squid allows requests from authenticated clients. Add the following line to the end of the file: `auth ntlm`.
  2. Step 2: Step 2: Restart Squid by running the command `sudo service squid restart` (or `sudo systemctl restart squid` on Linux systems).
  3. Step 3: Step 3: Verify that the changes have taken effect by checking the Squid logs for any errors. You can do this by running the command `sudo grep 'TCP Denied/407' /var/log/squid/squid.log`.

Disable TCP Deny and Allow Overriding

  1. Step 1: Step 1: Open the squid.conf file in a text editor and navigate to the http_port parameter. Add the following line to the end of the file: `DenyOverriding off`.
  2. Step 2: Step 2: Restart Squid by running the command `sudo service squid restart` (or `sudo systemctl restart squid` on Linux systems).
  3. Step 3: Step 3: Verify that the changes have taken effect by checking the Squid logs for any errors. You can do this by running the command `sudo grep 'TCP Denied/407' /var/log/squid/squid.log`.

💡 Conclusion

To resolve the 'TCP Denied/407' error in Squid, you can try one of two methods: configuring Squid to allow HTTP requests from authenticated clients or disabling TCP Deny and Allow Overriding. Follow the steps outlined above to implement these fixes and regain access to blocked websites.

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