# Unable to fetch custom indices data in ECS

**URL:** <https://discuss.elastic.co/t/unable-to-fetch-custom-indices-data-in-ecs/267742>\
**Category:** Elastic Security\
**Created:** [March 19, 2021, 3:25am UTC](https://discuss.elastic.co/t/unable-to-fetch-custom-indices-data-in-ecs/267742 "2021-03-19T03:25:00Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![aditi\_salunke](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/aditi_salunke/32/85600_2.png) [@aditi\_salunke](https://discuss.elastic.co/u/aditi_salunke)\
**Post date:** [March 19, 2021, 3:25am UTC](https://discuss.elastic.co/t/unable-to-fetch-custom-indices-data-in-ecs/267742/1 "2021-03-19T03:25:00Z")

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If i add my custom indices in data sources on elastic security  
then how should i map field in ecs

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**Author:** ![spong](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/spong/32/54343_2.png) [@spong](https://discuss.elastic.co/u/spong)\
**Post date:** [March 19, 2021, 1:45pm UTC](https://discuss.elastic.co/t/unable-to-fetch-custom-indices-data-in-ecs/267742/2 "2021-03-19T13:45:20Z")

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Hey there @aditi_salunke -- welcome to the community! 👋

So when adding custom indices you'll want to use the [Elastic Security ECS field reference](https://www.elastic.co/guide/en/security/master/siem-field-reference.html) as a guide for what fields are used in Elastic Security, and for help with the mapping I highly recommend checking out this [blog post](https://www.elastic.co/blog/migrating-to-elastic-common-schema-in-beats-environments) (for beats), [this webinar](https://www.elastic.co/webinars/migrating-data-to-elastic-common-schema-ecs) for both beats/external events and the [ecs-mapper tool](https://github.com/elastic/ecs-mapper).

Hope this is helpful, and look forward to hearing your feedback in using Elastic Security! 🙂

Cheers!  
Garrett

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<div class="post-metadata">

**Author:** ![aditi\_salunke](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/aditi_salunke/32/85600_2.png) [@aditi\_salunke](https://discuss.elastic.co/u/aditi_salunke)\
**Post date:** [March 24, 2021, 5:54am UTC](https://discuss.elastic.co/t/unable-to-fetch-custom-indices-data-in-ecs/267742/3 "2021-03-24T05:54:21Z")

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hi @spong thanks for the help. 🙂

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [April 21, 2021, 5:54am UTC](https://discuss.elastic.co/t/unable-to-fetch-custom-indices-data-in-ecs/267742/4 "2021-04-21T05:54:49Z")

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