# Is there the documents about built-in variables on Logstash configuration? **URL:** \ **Category:** Logstash\ **Created:** [May 26, 2018, 12:40pm UTC](https://discuss.elastic.co/t/is-there-the-documents-about-built-in-variables-on-logstash-configuration/133392 "2018-05-26T12:40:29Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Takeo](https://avatars.discourse-cdn.com/v4/letter/t/2acd7d/32.png) [@Takeo](https://discuss.elastic.co/u/Takeo)\ **Post date:** [May 26, 2018, 12:40pm UTC](https://discuss.elastic.co/t/is-there-the-documents-about-built-in-variables-on-logstash-configuration/133392/1 "2018-05-26T12:40:30Z")
I need the IP address of source host that send data to Logstash input. I wonder if there is the documents about some built-in(?) variables that can be used input plug-in on Logstash configuration. Is there that somewhere? where? ---
**Author:** ![magnusbaeck](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/magnusbaeck/32/44943_2.png) [@magnusbaeck](https://discuss.elastic.co/u/magnusbaeck)\ **Post date:** [May 27, 2018, 12:49pm UTC](https://discuss.elastic.co/t/is-there-the-documents-about-built-in-variables-on-logstash-configuration/133392/2 "2018-05-27T12:49:33Z")
Sometimes the documentation of input plugins describes which fields are set, but don't count on it. You can make experiments, read the source code, or ask specific questions here. ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [June 24, 2018, 12:49pm UTC](https://discuss.elastic.co/t/is-there-the-documents-about-built-in-variables-on-logstash-configuration/133392/3 "2018-06-24T12:49:35Z")
Closed on June 24, 2018, 12:49pm UTC This topic was automatically closed 28 days after the last reply. New replies are no longer allowed.