Netflow Receiver

The netflow receiver is capable of listening for netflow, sflow or IPFIX UDP traffic and generating log entries based on the flow content.

This gives Opentelemetry users the capability of monitoring network traffic, and answer questions like:

• Which protocols are passing through the network?
• Which servers and clients are producing the highest amount of traffic?
• What ports are involved in these network calls?
• How many bytes and packets are being sent and received?

The receiver listens for flows and decodes them using the templates that are sent by the flow producers. The data then is converted to JSON and produces structured log records.

Using the receiver

Docker

A collector with the receiver can be run with docker:

# windows
docker run --name otelcol -v ${PWD}/config.yaml:/etc/otel/config.yaml -p 2055:2055/udp dlopes7/otelcol-netflow-receiver

# linux
docker run --name otelcol -v $(pwd)/config.yaml:/etc/otel/config.yaml -p 2055:2055/udp dlopes7/otelcol-netflow-receiver

This repo contains an example of a config.yaml:

receivers:
  netflow:
    hostname: "0.0.0.0"
    scheme: netflow
    port: 2055
    sockets: 16
    workers: 32

processors:
  batch:
    send_batch_size: 30 
    timeout: 30s

exporters:
  debug:
  otlphttp:
    endpoint: https://<environment>.live.dynatrace.com/api/v2/otlp
    headers: 
      Authorization: "Api-Token <dynatrace_ingest_logs_token>"

service:
  pipelines:
    logs:
      receivers: [netflow]
      processors: [batch]
      exporters: [debug, otlphttp]
  telemetry:
    logs:
      level: debug

Will start a collector listening on the port 2055 UDP of the host for netflow data. You can send demo netflow data to that container with:

docker run --net="host" dlopes7/netflow-generator -r 10 -t localhost -p 2055

Building a collector

Build a collector with the receiver by using:

Example builder-config.yaml:

dist:
  name: otelcol-dev
  description: Basic OTel Collector distribution for Developers
  output_path: ./otelcol-dev

exporters:
  - gomod:
      go.opentelemetry.io/collector/exporter/debugexporter v0.116.0
  - gomod:
      go.opentelemetry.io/collector/exporter/otlphttpexporter v0.116.0

processors:
  - gomod:
      go.opentelemetry.io/collector/processor/batchprocessor v0.116.0

receivers:
  - gomod: github.com/dynatrace-extensions/netflowreceiver v1.3.0
    path: .

The collector can be built with:

go install go.opentelemetry.io/collector/cmd/builder@latest
builder --config builder-config.yaml 

Netflow receiver

Status
Stability	development: logs
Distributions	[]
Issues
Code Owners	@evan-bradley, @dlopes7

The netflow receiver can listen for netflow, sflow, and ipfix data and convert it to OpenTelemetry logs. The receiver is based on the goflow2 project.

This gives OpenTelemetry users the capability of monitoring network traffic, and answer questions like:

• Which protocols are passing through the network?
• Which servers and clients are producing the highest amount of traffic?
• What ports are involved in these network calls?
• How many bytes and packets are being sent and received?

Getting started

By default the receiver will listen for ipfix and netflow on port 2055. The receiver can be configured to listen on different ports and protocols.

Example configuration:

receivers:
  netflow:
    - scheme: netflow
      port: 2055
      sockets: 16
      workers: 32

processors:
  batch:
    send_batch_size: 2000
    timeout: 30s

exporters:
  debug:
    verbosity: detailed

service:
  pipelines:
    logs:
      receivers: [netflow]
      processors: [batch]
      exporters: [debug]
  telemetry:
    logs:
      level: debug

We recommend using the batch processor to reduce the number of log requests being sent to the exporter. The batch processor will batch log records together and send them in a single request to the exporter.

You would then configure your network devices to send netflow, sflow, or ipfix data to the Collector on the specified ports.

Configuration

Field	Description	Examples	Default
scheme	The type of flow data that to receive	sflow, netflow, flow	netflow
hostname	The hostname or IP address to bind to	localhost	0.0.0.0
port	The port to bind to	2055 or 6343	2055
sockets	The number of sockets to use	1	1
workers	The number of workers used to decode incoming flow messages	2	2
queue_size	The size of the incoming netflow packets queue	1000	1000000

Data format

The netflow data is standardized for the different schemas and is converted to OpenTelemetry logs following the semantic conventions

The output will adhere the format:

{
    "destination": {
        "address": "192.168.0.1",
        "port": 22
    },
    "flow": {
        "end": 1731073104662487000,
        "sampler_address": "192.168.0.2",
        "sequence_num": 49,
        "start": 1731073077662487000,
        "time_received": 1731073138662487000,
        "type": "NETFLOW_V5"
    },
    "io": {
        "bytes": 529,
        "packets": 378
    },
    "source": {
        "address": "192.168.0.3",
        "port": 40
    },
    "transport": "TCP",
    "type": "IPv4"
}