should I create Out put for each Input that I have created?
No. Creating Input is only required to ingest data into Graylog and access it by search, stream or dashboards.
Another question is that the relation between the global inputs and the streams?
Global Input: Read what it says on the create new input windows. “Should this input start on all nodes” (see enclosed image). You must have noticed then when you check the Global option the following option to select a Node disappears.
Graylog can be configured on multiple servers to scale the service for high throughput. You can create an input that is only available on one particular node or you can make this Gloabl and thisinput will be available on all nodes. This is a global input.
Streams: is simply the way to view your log events. By default, you’ll get an “All Messages” stream. This will aggregate ALL the messages from all the inputs you have configured.
Now, if you want to create a view to view only the messages from your firewalls, you can create a stream.
Once created you can use the Manage Rules option to give graylog the instruction.
I have created an input for syslog UDP, but not very much result in the received message and the histogram section
Check the All Messages stream and you’ll find all the messages from your inputs.