Install logstash-filter-de_dot failed?

Elastic Stack Logstash
1

Hi,
I am trying to install logstash-filter-de_dot plugin with below command.
/opt/logstash/bin/plugin install logstash-filter-de_dot

But it shows below error.
Validating logstash-filter-de_dot
Unable to download data from https://rubygems.org - SocketError: initialize: name or service not known (https://rubygems.org/latest_specs.4.8.gz)
ERROR: Installation aborted, verification failed for logstash-filter-de_dot

my logstash version is logstash 2.1.3
What am I missing?

2

Can you ping rubygems.com from the host? It looks like it's either a general internet accessibility or a DNS issue.

3

root@hp-dx:~# ping https://rubygems.org
ping: unknown host https://rubygems.org

4

No, ping rubygems.org.

5

ping: unknown host rubygems.org

6

Can you ping any other host on the internet?

If not then it's a DNS issue.

7

my dns server setting as follows,
nameserver 8.8.4.4
nameserver 8.8.8.8

ping yahoo is success