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Client packet capture

Remote captures allow administrators to collect packet captures (PCAPs) and Cloudflare One Client diagnostic logs directly from end user devices. A packet capture is a recording of network traffic at the packet level. This data can be used to troubleshoot network problems, investigate security incidents, and identify performance bottlenecks.

Devices must be actively connected to the Internet for remote captures to run.

To capture data from a remote device:

1. In Cloudflare One ↗, go to DEX > Remote captures.
2. Select up to 10 devices that you want to run a capture on. Devices must be registered in your Zero Trust organization.
3. Configure the types of captures to run.

   • Packet captures (PCAP): Performs packet captures for traffic outside of the WARP tunnel (default network interface) and traffic inside of the WARP tunnel (virtual interface).

   • Device diagnostic logs: Generates a Cloudflare One Client diagnostic log of the past 96 hours. To include a routing test for all IPs and domains in your Split Tunnel configuration, select Test all routes.

4. Select Run diagnostics.

DEX will now send capture requests to the configured devices. If the Cloudflare One Client is disconnected, the capture will time out after 10 minutes.

To view a list of captures, go to Insights > Digital experience > Diagnostics. The Status column displays one of the following options:

• Success: The capture is complete and ready for download. Any partially successful captures will still upload to Cloudflare. For example, there could be a scenario where the PCAP succeeds on the primary network interface but fails on the WARP tunnel interface. You can review PCAP results to determine which PCAPs succeeded or failed.
• Running: The capture is in progress on the device.
• Pending Upload: The capture is complete but not yet ready for download.
• Failed: The capture has either timed out or encountered an error. To retry the capture, check the Cloudflare One Client version and connectivity status, then start a new capture.

1. In Cloudflare One ↗, go to DEX > Remote captures.
2. Find a successful capture.
3. Select the three-dot menu and select Download.

This will download a ZIP file to your local machine called <capture-id>.zip. DEX will store capture data according to our log retention policy.

The downloaded PCAP folder contains three files:

• capture-default.pcap: Packet captures for the primary network interface.
• capture-tunnel.pcap: Packet captures for traffic inside of the WARP tunnel.
• results.json: Reports successful and failed packet captures.

You can analyze .pcap files using Wireshark or another third-party packet capture tool.

Refer to Cloudflare One Client diagnostic logs for a description of each file.

The diagnostics analyzer highlights what Cloudflare determines to be the most important detection events in a warp-diag log. You can use the detection report to help parse your log files and identify the root cause of client issues. The diagnostics analyzer is only available for logs collected via the dashboard.

To access the diagnostics analyzer:

1. In Cloudflare One ↗, go to DEX > Remote captures.

2. Locate an existing warp-diag log from the list or select Run diagnostics to generate a new warp-diag log.

3. Select the three dots for the warp-diag log that you want to analyze, then select View Device Diag.

   The Overview tab will display an AI-generated summary of the results, a list of detection events, and basic device information.

   Explanation of the fields

   Field	Description
   Detection type	A common Cloudflare One Client issue that can appear in the diagnostic logs.
   Occurrences	Number of times an issue was detected in the logs.
   Severity level	Indicates the impact of the issue on Cloudflare One Client functionality. The severity levels are: Critical: Issue causes complete loss of functionality. Warning: Issue causes degraded functionality but core features should still work. No detection: Issue was not detected in the logs.
   Operating system	OS and OS version of the device.
   Cloudflare One Client version	Cloudflare One Client release version
   Profile ID	device profile UUID
   Service mode	Client mode
   Configuration name	Name of the Zero Trust organization that the Cloudflare One Client is connected to.
   Device ID	ID generated by the Cloudflare One Client.

4. Select a detection type for more information about the event and recommended next steps.

Cloudflare DEX will store the warp-diag log and its detection report per our log retention policy. To save a copy onto your local machine, download the log file and go to the JSON file tab to copy the report in JSON format.

• Packet captures are subject to the following limits:

  Limit Type	Maximum Value
  Time limit	600 seconds
  File size	50 MB
  Packet size	1500 bytes

• Cloudflare One Client diagnostic logs have no file size limit, but files larger than 100 MB cannot be uploaded to Cloudflare and must be shared directly with the admin.

• Windows devices do not support concurrent remote captures. If you start a remote capture while another is in progress, the second capture will fail immediately.

• PCAPs will fail on Windows if you have another third-party packet capture tool (such as, Packet Monitor pktmon) running.

• On Windows, packet captures may fail on devices configured with a non-English language due to limitations with the underlying PktMon tool.