INTEGRITY Cloudflare Docs

Captive portal detection

Captive portals are used by public Wi-Fi networks (such as airports, coffee shops, and hotels) to make a user agree to their Terms of Service or provide payment before allowing access to the Internet. When a user connects to the Wi-Fi, the captive portal blocks all HTTPS traffic until the user completes a captive portal login flow in their browser. This prevents the Cloudflare One Client (formerly WARP) from connecting to Cloudflare. At the same time, the Cloudflare One Client creates firewall rules on the device to send all traffic to Cloudflare. The user is therefore unable to access the captive portal login screen unless they temporarily disconnect the Cloudflare One Client.

Allow users to connect to captive portals

To allow users to connect through a captive portal, administrators can configure the following device client settings:

No user interaction required

User interaction required

How captive portal detection works

If the Cloudflare One Client cannot establish a connection to Cloudflare, it will:

  1. Start the captive portal timer.

  2. Send a series of requests to the Cloudflare captive portal URLs and other OS and browser-specific captive portal URLs. These requests are sent outside of the WARP tunnel.

  3. If a request is intercepted, the Cloudflare One Client assumes the network is behind a captive portal and fully opens the system firewall. While the firewall is open, all device traffic will bypass the Cloudflare One Client.

  4. Re-enable the firewall after the user successfully connects to the portal or after the timeout period expires.

Limitations

Get captive portal logs Beta

Feature availability

Client modes Zero Trust plans
All modes All plans
System Availability Minimum client version
Windows 2025.4.589.1
macOS 2025.4.589.1
Linux
iOS
Android
ChromeOS

Captive portal logs are used by Cloudflare Support to troubleshoot Cloudflare One Client captive portal issues. When an end user reports an issue with a captive portal, the IT administrator can ask the user to collect captive portal logs on their device. The administrator can then attach the logs to a Cloudflare Support ticket.

To get captive portal logs:

  1. Open a terminal window.

  2. Run the following command:

    warp-diag captive-portal
  3. When prompted with You're currently connected via interface '<INTERFACE>' (<SSID>). Is this interface connected to the network causing issues?, select Yes to confirm.

  1. Open the Cloudflare One Client.
  2. Go to Settings (gear icon) > Preferences > Advanced.
  3. Select Collect Captive Portal Diag.
  4. The Cloudflare One Client will ask if the device is connected (or attempting to connect) to the Wi-Fi network that is causing issues. Select Yes to confirm.

Once the diagnostic finishes running, the Cloudflare One Client will place a warp-captive-portal-diag-<date>-<time>.zip file on the user's desktop. The end user can now share this file with their IT administrator.