UPDATE:
Running the command curl localhost:9200/_cat/indices from the Server which should be receiving the logs (the one with the entire ELK stack installed) I get the following data returned: yellow open .kibana 1 1 1 0 2.5kb 2.5kb
I don't know what that means, but it's something different... 
UPDATE #2:
Turns out, the config files may have issues. If I change the config in the receiving server's elasticsearch network.host declaration from localhost to the public IP of the server lets me curl the IP:9200. It returns {"error":"NullPointerException[null]","status":500}
However, it shows a fatal error on Kibana until I change it back.
Not sure what's going on. just to clarify the problem:
I have
1 CentOS 7 server that has Elasticsearch, Logstash, and Kibana.
1 CentOS 6 host which should forward logs to the CentOS 7 server using Logstash-Forwarder
I'm able to access the Kibana web interface, but it doesn't allow me to configure a default index. The box is grayed out and it says unable to fetch mapping.Do you have indices matching the pattern?