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Collect packet captures (PCAPs)

After a packet capture is requested and the capture is collected, the output is contained within one or more files in PCAP file format. Before starting a full type packet capture, you must first follow instructions for configuring a bucket.

​​ Send a packet capture request

Currently, when a packet capture is requested, packets flowing at the edge through the Magic Transit system are captured, and the system is magic-transit.

Cloudflare supports two types of packet captures:

  • Simple: Simple packets are best for debugging and providing a global picture across all data centers. Simple packets generate single, smaller files and only contain the first 160 bytes of the payload. Sampled packets are collected across all edge metals to build a PCAP file.
  • Full: Full packets are best for targeted data collection with a detailed view into a single data center. Full packets generate multiple large files, and they are captured within a given data center or set of data centers and sent to either a GCP or AWS bucket specified by the user.

​​ Packet capture limits

Simple and Full

  • time_limit: The minimum value is 1 and maximum value is 300.
  • packet_limit: The minimum value is 1 and maximum value is 10000.

Full

  • byte_limit: The minimum value is 1 and maximum value is 1000000000.
  1. Log in to your Cloudflare dashboard and select Magic Transit.
  2. On the Magic Transit page next to Packet captures, select Start a capture.
  3. Select the Captures tab and select Start a capture.
  4. From Packet captures - Capture configuration, choose a capture type and select Next.
  5. Fill out the required fields to begin the capture and then select Start.

The main Packet captures page displays a list of captures.

The PCAPs API needs both system and type to be specified to start a capture. A PCAP’s system is the product or logical subsystem where packets are captured, and a PCAP’s type is how the captured packets are built into a PCAP file.

Currently, you can only send one collect request per minute for simple PCAPs, and you can only have one running or pending full PCAP at a time.

Full PCAP

For full PCAP requests, refer to the required parameters listed at Create full PCAP requests. Note that full packet captures require two more parameters than simple packets.

The full PCAP request endpoint also contains optional fields you can use to limit the amount of packets captured. Both full and simple packet requests contain an optional filter_v1 parameter you can use to filter packets by IPv4 Source address, for example. For a full list of the filter options, refer to the parameter lists above.

Leave filter_v1 empty to collect all packets without any filtering.

Full PCAP example request
curl -X POST https://api.cloudflare.com/client/v4/accounts/${account_id}/pcaps \
-H 'Content-Type: application/json' \
-H "X-Auth-Email: ${email}" \
-H "X-Auth-Key: ${auth_key}" \
--data '{
"filter_v1": {},
"time_limit": 300,
"packet_limit": 10000,
"byte_limit": 100000000,
"type": "full",
"colo": "ORD",
"system": "magic-transit",
"destination_conf": "${bucket}"
}'

While the collection is in progress, the response returns the status field as pending. You must wait for the PCAP collection to complete before downloading the file. When the PCAP is ready to download, the status changes to success.

Full PCAP example response
{
"result": {
"id": "7d7c88382f0b4d5daa9587aa45a1a877",
"submitted": "2022-06-02T18:38:22.269047Z",
"filter_v1": {},
"time_limit": 300,
"status": "pending",
"type": "full",
"system": "magic-transit",
"packet_limit": 10000,
"byte_limit": 100000000,
"colo": "ORD",
"destination_conf": "gs://test-magic-pcaps"
},
"success": true,
"errors": [],
"messages": []
}
Simple PCAP

To create a simple PCAP request, send a JSON body with the required parameter listed at Create simple PCAP request.

Leave filter_v1 to collect all packets without any filtering.

Simple PCAP example request
curl -X POST https://api.cloudflare.com/client/v4/accounts/${account_id}/pcaps \
-H 'Content-Type: application/json' \
-H 'X-Auth-Email: [email protected]' \
-H 'X-Auth-Key: 00000000000' \
--data '{
"filter_v1": {
"source_address": "1.2.3.4",
"source_port": 123,
"destination_address": "5.6.7.8",
"destination_port": 80,
"protocol": 6
},
"time_limit": 300,
"packet_limit": 10000,
"type": "simple",
"system": "magic-transit"
}'

The response is a JSON body that contains the details of the job running to build the packet capture. The response contains a unique identifier for the packet capture request along with the details sent in the request.

Simple PCAP example response
{
"result": {
"id": "6d1f0aac13cd40e3900d29f5dd0e8a2b",
"submitted": "2021-12-20T17:29:20.641845Z",
"filter_v1": {
"source_address": "1.2.3.4",
"source_port": 123,
"destination_address": "5.6.7.8",
"destination_port": 80,
"protocol": 6
},
"time_limit": 60,
"status": "pending",
"packets_remaining": 0,
"type": "simple",
"system": "magic-transit"
},
"success": true,
"errors": [],
"messages": []
}

​​ Check packet capture status

  1. Log in to your Cloudflare dashboard and select Magic Transit.
  2. On the Magic Transit page next to Packet captures, select Start a capture.
  3. From the Packet Capture page, select the Captures tab.

To check the status of a running job, send a request to the endpoint and specify the PCAP identifier. The PCAP identifier is received in the response of a collect request as shown in the previous step.

curl -X GET https://api.cloudflare.com/client/v4/accounts/${account_id}/pcaps/${pcap_id} \
-H 'Content-Type: application/json' \
-H 'X-Auth-Email: [email protected]' \
-H 'X-Auth-Key: 00000000000'

The response will be similar to the one received when requesting a PCAP collection.

Simple PCAP example result
{
"result": {
"id": "6d1f0aac13cd40e3900d29f5dd0e8a2b",
"submitted": "2021-12-20T17:29:20.641845Z",
"filter_v1": {
"source_address": "1.2.3.4",
"source_port": 123,
"destination_address": "5.6.7.8",
"destination_port": 80,
"protocol": 6
},
"time_limit": 120,
"status": "success",
"packets_remaining": 0,
"type": "simple",
"system": "magic-transit"
},
"success": true,
"errors": [],
"messages": []
}

The capture status displays one of the following options:

  • Complete: The capture request is done and ready for download.
  • In progress: The capture request was captured but still processing.
  • Failure: The capture . If this occurs, verify your ownership information.

​​ Download packet captures

After your request finishes processing, you can download your packet captures.

  1. Log in to your Cloudflare dashboard and select Magic Transit.
  2. On the Magic Transit page next to Packet captures, select Start a capture.
  3. From the Packet captures page, select the Captures tab.
  4. Locate your packet capture you want to download and under Captures, select the link to download it.

Packet captures are available to download when the Status displays Success.

For more information on how to process multiple saved capture files into a single output file, refer to Wireshark’s mergecap documentation.

Full PCAPs

To obtain full PCAPs, download the files from the bucket specified in destination_conf after the PCAP’s status is success. You may find multiple files named pcap_<pcap_id>.pcap per capture as captures can occur across multiple machines.

Simple PCAPs

Once the simple PCAP collection is complete, you can download the PCAP by specifying the PCAP identifier used earlier.

curl -X GET https://api.cloudflare.com/client/v4/accounts/${account_id}/pcaps/${pcap_id}/download \
-H 'Content-Type: application/json' \
-H 'X-Auth-Email: [email protected]' \
-H 'X-Auth-Key: 00000000000' \
--output download.pcap

​​ List packet captures

  1. Log in to your Cloudflare dashboard and select Magic Transit.
  2. On the Magic Transit page next to Packet captures, select Start a capture.
  3. From the Packet captures page, select the Captures tab.

The list of packet captures associated with your account displays.

To view a list of sent requests, use the following command:

List request example
curl -X GET https://api.cloudflare.com/client/v4/accounts/${account_id}/pcaps \
-H 'Content-Type: application/json' \
-H 'X-Auth-Email: [email protected]' \
-H 'X-Auth-Key: 00000000000'

The response returns an array that includes up to 50 sent requests, which includes completed and ongoing requests.

List response example
{
"result": [
{
"id": "43adab5adeca4dab9c51f4b7f70f2ec3",
"submitted": "2021-12-15T03:04:09.277394Z",
"filter_v1": {},
"time_limit": 120,
"status": "success",
"packets_remaining": 0,
"type": "simple",
"system": "magic-transit"
}
],
"success": true,
"errors": [],
"messages": []
}