Cherry-pick #18986 to 7.x: Add minimum cache TTL for successful DNS responses#20525
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andrewkroh merged 3 commits intoelastic:7.xfrom Aug 11, 2020
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Cherry-pick #18986 to 7.x: Add minimum cache TTL for successful DNS responses#20525andrewkroh merged 3 commits intoelastic:7.xfrom
andrewkroh merged 3 commits intoelastic:7.xfrom
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An enhancement to add a minimum alternative cache TTL to the libbeat dns processor for successful DNS responses. This ensures that TTL=0 successful reverse DNS responses can be cached to avoid sending the same reverse DNS request again within a short period of time. The libbeat dns processor is used as a reverse DNS annotator for auditbeat events. Some of these IP addresses respond to reverse DNS requests with TTL=0 in the responses. These were causing load issues for my systems when I had the reverse DNS processor enabled for auditbeat. The new settings is `success_cache.min_ttl`. Closes elastic#18709 Signed-off-by: Peter Ansell <p_ansell@yahoo.com> Co-authored-by: Marc Guasch <marc.guasch@elastic.co> (cherry picked from commit 72da5a6)
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adriansr
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Aug 11, 2020
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Cherry-pick of PR #18986 to 7.x branch. Original message:
What does this PR do?
An enhancement to add a minimum alternative cache TTL to the
libbeatdns processor for successful DNS responses. This ensures thatTTL=0successful reverse DNS responses can be cached to avoid sending the same reverse DNS request again within a short period of time.Why is it important?
The
libbeatdns processor is used as a reverse DNS annotator forauditbeatevents. Some of these IP addresses respond to reverse DNS requests withTTL=0in the responses. These were causing load issues for my systems when I had the reverse DNS processor enabled for auditbeat.Checklist
- [ ] I have commented my code, particularly in hard-to-understand areas- [ ] I have made corresponding change to the default configuration filesCHANGELOG.next.asciidocorCHANGELOG-developer.next.asciidoc.Author's Checklist
How to test this PR locally
The
auditbeatsystem/socketmodule that I had the issue with is not open-sourced, so I have not been able to test its completeness myself. I am submitting this in good faith that it can be completed by someone with access to that module for testing purposes, or who is experienced enough to add the necessary tests here.Related issues
Use cases
This will add a cache for successful DNS responses that will not always correspond to the upstream DNS TTL value. This is acceptable as it avoids a possible denial-of-service for
auditbeatenabled systems, and it is configurable by users.