# DNS Filter - only first value in reverse array works

**URL:** <https://discuss.elastic.co/t/dns-filter-only-first-value-in-reverse-array-works/69301>\
**Category:** Logstash\
**Created:** [December 16, 2016, 3:06pm UTC](https://discuss.elastic.co/t/dns-filter-only-first-value-in-reverse-array-works/69301 "2016-12-16T15:06:32Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![sliddjur](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/sliddjur/32/65260_2.png) [@sliddjur](https://discuss.elastic.co/u/sliddjur)\
**Post date:** [December 16, 2016, 3:06pm UTC](https://discuss.elastic.co/t/dns-filter-only-first-value-in-reverse-array-works/69301/1 "2016-12-16T15:06:32Z")

</div>

This is my filter:

```
filter {
        if [type] == "netflow" {

        mutate {
                add_field => {
                        "[netflow][ipv4_dst_host]" => "%{[netflow][ipv4_dst_addr]}"
                        "[netflow][ipv4_src_host]" => "%{[netflow][ipv4_src_addr]}"
                        }
                }
        dns {
                # DNS Filter
                nameserver => ["172.18.65.20", "172.18.65.30"]
                action => "replace"
                reverse => ["[netflow][ipv4_dst_host]", "[netflow][ipv4_src_host]" ]
                }
        }
}

```

Only [netflow][ipv4\_dst\_host] is filled with correct value.

Reverse lookups ipv4\_src\_host does never work.

Have I written some syntax wrong?

---

<div class="post-metadata">

**Author:** ![warkolm](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/warkolm/32/39224_2.png) [@warkolm](https://discuss.elastic.co/u/warkolm)\
**Post date:** [December 17, 2016, 1:08am UTC](https://discuss.elastic.co/t/dns-filter-only-first-value-in-reverse-array-works/69301/2 "2016-12-17T01:08:10Z")

</div>

What version are you on?

---

<div class="post-metadata">

**Author:** ![sliddjur](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/sliddjur/32/65260_2.png) [@sliddjur](https://discuss.elastic.co/u/sliddjur)\
**Post date:** [December 17, 2016, 10:10pm UTC](https://discuss.elastic.co/t/dns-filter-only-first-value-in-reverse-array-works/69301/3 "2016-12-17T22:10:41Z")

</div>

I am on version 5.1.

Why does the plugin have an array, if it only can reverse one string?

Should I just enter two filters instead?

---

<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [January 14, 2017, 10:11pm UTC](https://discuss.elastic.co/t/dns-filter-only-first-value-in-reverse-array-works/69301/4 "2017-01-14T22:11:24Z")

</div>

This topic was automatically closed 28 days after the last reply. New replies are no longer allowed.