anchor.diff:  [[logstash]]
   === Using Logstash with Shield
   
  -IMPORTANT: Shield 1.0+ is compatible with Logstash 1.5 and above.
  +IMPORTANT: Shield 2.0+ is compatible with Logstash 2.0 and above.
   
   Logstash provides Elasticsearch https://www.elastic.co/guide/en/logstash/current/plugins-outputs-elasticsearch.html[output], https://www.elastic.co/guide/en/logstash/current/plugins-inputs-elasticsearch.html[input] and https://www.elastic.co/guide/en/logstash/current/plugins-filters-elasticsearch.html[filter] plugins
   used to index and retrieve documents through HTTP, transport or client node protocols.
  
positive.code: [[ls-http-auth-pki]]
  ===== PKI Authentication
  
  Elasticsearch Output version 1.0.1 onwards supports the use of X.509 client-certificate to authenticate Logstash requests. To enable this you need to set up the following configuration parameters:
  
  [source, shell]
  --------------------------------------------------
  input { ... }
  output {
    elasticsearch {
      protocol => "http"
      ...
      keystore => ... # string
      keystore_password => ... # string
  
negative.code: input { ... }
  output {
    elasticsearch {
      ...
      ssl => true
      cacert => '/path/to/cert.pem' <1>
  