How to troubleshoot logstash and es issues?

My issue is that I cannot see the index log message from kibana.
Here is version I am using: All of them are installed on the same virtual machine.
CentOS 7
Oracle JDK 8
Kibana 4.5.2
Elaticsearch 2.3.4
logstash 2.3.4
filebeat 1.2.3

my logstash config file is like:
input {
beats {
port => 5044
filter {
output {
codec => rubydebug

I can see pretty json is printed out in log /var/log/logstash/logstash.stdout.
But I cannot see any info in Kibana, and index was created and worked fine yesterday. I checked all those service is running, And didn't find any error message in either logstash.log or elasticsearch.log.

How can I do troubleshooting for this?

Try running with verbose enabled to see if anything else shows up.

how to 'run with verbose enabled'? I can run it manually and see the json print out. But there is no error message.

I think i have a similar issue , my stack is also the same but not sure of the versions. What i have seen is though all the services are show as running the logstash log shows logstash pipeline shutdown.