Frequently Asked Questions

This section contains frequently asked questions about Packetbeat. Also check out the Packetbeat discussion forum.

The client_server and server fields are empty when Packetbeat is not configured to capture information about the network topology.

To capture information about the network topology, set the save_topology configuration option to true and make sure that you are sending the output to Elasticsearch.

The index template might not be loaded correctly. See Step 3: Loading the Index Template in Elasticsearch.

The interface needs to be set to promiscuous mode. Run the following command:

ip link set <device_name> promisc on

For example: ip link set enp5s0f1 promisc on

Packetbeat is unable to capture traffic from the loopback device (127.0.0.1 traffic) because the Windows TCP/IP stack does not implement a network loopback interface, making it difficult for Windows packet capture drivers like WinPcap to sniff traffic.

As a workaround, you can try installing Npcap, an update of WinPcap. Make sure that you restart Windows after installing Npcap. Npcap creates an Npcap Loopback Adapter that you can select if you want to capture loopback traffic.

For the list of devices shown here, you would configure Packetbeat to use device 4:

PS C:\Users\vagrant\Desktop\packetbeat-1.2.0-windows> .\packetbeat.exe -devices
0: \Device\NPF_NdisWanBh (NdisWan Adapter)
1: \Device\NPF_NdisWanIp (NdisWan Adapter)
2: \Device\NPF_NdisWanIpv6 (NdisWan Adapter)
3: \Device\NPF_{DD72B02C-4E48-4924-8D0F-F80EA2755534} (Intel(R) PRO/1000 MT Desktop Adapter)
4: \Device\NPF_{77DFFCAF-1335-4B0D-AFD4-5A4685674FAA} (MS NDIS 6.0 LoopBack Driver)

Packetbeat has an internal timeout that it uses to time out transactions and TCP connections when no packets have been seen for a long time.

To process long running transactions, you can specify a larger value for the transaction_timeout option. However, keep in mind that very large timeout values can increase memory usage if messages are lost or transaction response messages are not sent.

If you need to limit bandwidth usage, we recommend that you configure the network stack on your OS to perform bandwidth throttling.

For example, the following Linux commands cap the connection between Packetbeat and Logstash by setting a limit of 50 kbps on TCP connections over port 5044:

tc qdisc add dev $DEV root handle 1: htb
tc class add dev $DEV parent 1:1 classid 1:10 htb rate 50kbps ceil 50kbps
tc filter add dev $DEV parent 1:0 prio 1 protocol ip handle 10 fw flowid 1:10
iptables -A OUTPUT -t mangle -p tcp --dport 5044 -j MARK --set-mark 10

Using OS tools to perform bandwidth throttling gives you better control over policies. For example, you can use OS tools to cap bandwidth during the day, but not at night. Or you can leave the bandwidth uncapped, but assign a low priority to the traffic.

You may have configured Logstash or Packetbeat incorrectly. To resolve the issue:

Logstash outputs remove @metadata fields automatically. Therefore, if Logstash instances are chained directly or via some message queue (for example, Redis or Kafka), the @metadata field will not be available in the final Logstash instance.

Beats are lightweight data shippers that you install as agents on your servers to send specific types of operational data to Elasticsearch. Beats have a small footprint and use fewer system resources than Logstash.

Logstash has a larger footprint, but provides a broad array of input, filter, and output plugins for collecting, enriching, and transforming data from a variety of sources.

For more information, see the Logstash Introduction and the Beats Overview.

The host running Logstash might be unreachable or the certificate may not be valid. To resolve your issue:

Here are some common errors and ways to fix them:

This happens because your certificate is only valid for the hostname present in the Subject field.

To resolve this problem, try one of these solutions:

This is not a SSL problem. It’s a networking problem. Make sure the two hosts can communicate.

This is not a SSL problem. Make sure that Logstash is running and that there is no firewall blocking the traffic.

A firewall is refusing the connection. Check if a firewall is blocking the traffic on the client, the network, or the destination host.

When Packetbeat exports a field of type dictionary, and the keys are not known in advance, the Discovery page in Kibana will display the field as a nested JSON object:

http.response.headers = {
        "content-length": 12,
        "content-type": "application/json"
}

To fix this you need to reload the index pattern in Kibana under the Management→Index Patterns, and the index pattern will be updated with a field for each key available in the dictionary:

http.response.headers.content-length = 12
http.response.headers.content-type = "application/json"