Filter "logstash-filter-dns" doesn't work

[da.frolov (Dmitriy)]

Hi, Amazing ElasticSearch Community!

English is my second language and I apologize in advance)))

I have a problem with filter in logstash "netflow.conf" file.

I collect the netflow data from my network devices, and I want to have the dns names src and dst hosts. I found that this can be done with plug-ins for logstash "filter-dns" and "filter-mutate". I installed these plugins and now I have this version:

localhost:/usr/share/logstash/bin# ./logstash-plugin list --verbose logstash-filter-dns
logstash-filter-dns (3.0.10)
localhost:/usr/share/logstash/bin# ./logstash-plugin list --verbose logstash-filter-mutate
logstash-filter-mutate (3.3.2)

I wrote the file netflow.conf and looks like this:

input {
     udp {
       port => 9996
       type => "netflow"
       codec => netflow {
         versions => [5,9,10]
       }
     }
}

filter{
 if [netflow][dst_addr] {
  mutate {
   add_field => { "[netflow][dst_hostname]" => "%{[netflow][dst_addr]}"}
  }
   dns {
    reverse => [ "[netflow][dst_hostname]" ]
    action => "replace"
    nameserver => [ "my dns server" ]
    hit_cache_size => 4096
    hit_cache_ttl => 900
    failed_cache_size => 512
    failed_cache_ttl => 900
    }
  }
}

output {
 if [type] == "netflow" {
  elasticsearch {
     hosts => ["http://localhost:9200"]
     index => "netflow-%{+YYYY.MM.dd}"
     }
   }
}

But this configuration doesn't work((((

I checked that I have a normal server response time:

# curl -w '\nlookup time:\t%{time_namelookup}\n' -o /dev/null -s http://www.google.com
lookup time:	0.028513

In logs file i don't have any problems with filters.dns:

# cat /var/log/logstash/logstash-plain.log | grep filters.dns
#

Please help me somebody!

P.S. Netflow working perfect