Logstash codec plugin to decrypt sflow
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Logstash Codec SFlow Plugin


Logstash codec plugin to decode sflow codec.

This codec manage flow sample, counter flow, expanded flow sample and expanded counter flow

For the (expanded) flow sample it is able to decode Ethernet, 802.1Q VLAN, IPv4, UDP and TCP header

For the (expanded) counter flow it is able to decode some records of type:

  • Generic Interface
  • Ethernet Interface
  • VLAN
  • Processor Information
  • HTTP
  • LAG


Currently this plugin does not manage all sflow counter and is not able to decode all kind of protocols. If needed you can aks for some to be added. Please provide a pcap file containing the sflow events of the counter/protocol to add in order to be able to implement it.

Tune reported fields

By default all those fields are removed from the emitted event:

%w(sflow_version header_size ip_header_length ip_dscp ip_ecn ip_total_length ip_identification ip_flags 
ip_fragment_offset ip_ttl ip_checksum ip_options tcp_seq_number tcp_ack_number tcp_header_length tcp_reserved 
tcp_is_nonce tcp_is_cwr tcp_is_ecn_echo tcp_is_urgent tcp_is_ack tcp_is_push tcp_is_reset tcp_is_syn tcp_is_fin 
tcp_window_size tcp_checksum tcp_urgent_pointer tcp_options vlan_cfi sequence_number flow_sequence_number vlan_type 
udp_length udp_checksum)

You can tune the list of removed fields by setting this parameter to the sflow codec optional_removed_field

frame_length_times_sampling_rate output field on (expanded) flow sample

This field is the length of the frame times the sampling rate. It permits to approximate the number of bits send/receive on an interface/socket.

You must first ensure to have well configured the sampling rate to have an accurate output metric (See: http://blog.sflow.com/2009/06/sampling-rates.html)

Human Readable Protocol

In order to translate protocols value to a human readable protocol, you can use the logstash-filter-translate plugin

filter {
      translate {
        field => protocol
        dictionary => [ "1", "ETHERNET",
                        "11", "IP"
        fallback => "UNKNOWN"
        destination => protocol
        override => true
      translate {
        field => eth_type
        dictionary => [ "2048", "IP",
                        "33024", "802.1Q VLAN"
        fallback => "UNKNOWN"
        destination => eth_type
        override => true
      translate {
        field => vlan_type
        dictionary => [ "2048", "IP"
        fallback => "UNKNOWN"
        destination => vlan_type
        override => true
      translate {
        field => ip_protocol
        dictionary => [ "6", "TCP",
                        "17", "UDP",
                        "50", "Encapsulating Security Payload"
        fallback => "UNKNOWN"
        destination => ip_protocol
        override => true

Build Status

This is a plugin for Logstash.

It is fully free and fully open source. The license is Apache 2.0, meaning you are pretty much free to use it however you want in whatever way.


Logstash provides infrastructure to automatically generate documentation for this plugin. We use the asciidoc format to write documentation so any comments in the source code will be first converted into asciidoc and then into html. All plugin documentation are placed under one central location.

Need Help?

Need help? Try #logstash on freenode IRC or the https://discuss.elastic.co/c/logstash discussion forum.


1. Plugin Developement and Testing


  • To get started, you'll need JRuby with the Bundler gem installed.

  • Create a new plugin or clone and existing from the GitHub logstash-plugins organization.

  • Install dependencies

bundle install


bundle exec rspec

The Logstash code required to run the tests/specs is specified in the Gemfile by the line similar to:

gem "logstash", :github => "elasticsearch/logstash", :branch => "1.5"

To test against another version or a local Logstash, edit the Gemfile to specify an alternative location, for example:

gem "logstash", :github => "elasticsearch/logstash", :ref => "master"
gem "logstash", :path => "/your/local/logstash"

Then update your dependencies and run your tests:

bundle install
bundle exec rspec

2. Running your unpublished Plugin in Logstash

2.1 Run in a local Logstash clone

  • Edit Logstash tools/Gemfile and add the local plugin path, for example:
gem "logstash-codec-sflow", :path => "/your/local/logstash-codec-sflow"
  • Update Logstash dependencies
rake vendor:gems
  • Run Logstash with your plugin
bin/logstash -e 'input { udp { port => 6343 codec => sflow }}'

At this point any modifications to the plugin code will be applied to this local Logstash setup. After modifying the plugin, simply rerun Logstash.

2.2 Run in an installed Logstash

  • Build your plugin gem
gem build logstash-codec-sflow.gemspec
  • Install the plugin from the Logstash home
bin/plugin install /your/local/plugin/logstash-codec-sflow.gem
  • Start Logstash and proceed to test the plugin


All contributions are welcome: ideas, patches, documentation, bug reports, complaints, and even something you drew up on a napkin.

Programming is not a required skill. Whatever you've seen about open source and maintainers or community members saying "send patches or die" - you will not see that here.

It is more important to me that you are able to contribute.

For more information about contributing, see the CONTRIBUTING file.