Urls to whitelist for logstash

Elastic Stack Logstash
1

Hi All,
I am trying to install plugin
logstash-output-email ,
logstash-filter-elapsed ,
logstash-filter-aggregate and
logstash-filter-date , in my secured AWS cluster.

But I am getting 'ERROR: Something went wrong when installing logstash-filter-date, message: 403 "Forbidden"

Could any one please help me on this?
Is it I am in secure(firewall restricted) and what are urls that I need to consider for whiteline

2

Whitelisting rubygems.org should be enough, but I'd record the network traffic with tcpdump or Wireshark to see exactly what's going on.