﻿---
title: Performing Core Operations
description: The plugins described in this section are useful for core operations, such as mutating and dropping events. 
url: https://www.elastic.co/elastic/docs-builder/docs/2437/reference/logstash/core-operations
---

# Performing Core Operations
The plugins described in this section are useful for core operations, such as mutating and dropping events.
<definitions>
  <definition term="date filter">
    Parses dates from fields to use as Logstash timestamps for events.
    The following config parses a field called `logdate` to set the Logstash timestamp:
    ```json
    filter {
      date {
        match => [ "logdate", "MMM dd yyyy HH:mm:ss" ]
      }
    }
    ```
  </definition>
  <definition term="drop filter">
    Drops events. This filter is typically used in combination with conditionals.
    The following config drops `debug` level log messages:
    ```json
    filter {
      if [loglevel] == "debug" {
        drop { }
      }
    }
    ```
  </definition>
  <definition term="fingerprint filter">
    Fingerprints fields by applying a consistent hash.
    The following config fingerprints the `IP`, `@timestamp`, and `message` fields and adds the hash to a metadata field called `generated_id`:
    ```json
    filter {
      fingerprint {
        source => ["IP", "@timestamp", "message"]
        method => "SHA1"
        key => "0123"
        target => "[@metadata][generated_id]"
      }
    }
    ```
  </definition>
  <definition term="mutate filter">
    Performs general mutations on fields. You can rename, remove, replace, and modify fields in your events.
    The following config renames the `HOSTORIP` field to `client_ip`:
    ```json
    filter {
      mutate {
        rename => { "HOSTORIP" => "client_ip" }
      }
    }
    ```
    The following config strips leading and trailing whitespace from the specified fields:
    ```json
    filter {
      mutate {
        strip => ["field1", "field2"]
      }
    }
    ```
  </definition>
  <definition term="ruby filter">
    Executes Ruby code.
    The following config executes Ruby code that cancels 90% of the events:
    ```json
    filter {
      ruby {
        code => "event.cancel if rand <= 0.90"
      }
    }
    ```
  </definition>
</definitions>