Install Mosquitto MQTT on Synology NAS Server

Install Mosquitto MQTT on Synology NAS Server.txt

From https://synocommunity.com add http://packages.synocommunity.com to your NAS package sources.
For that, go to NAS->Package Cnter->Click Settings->Package Sources tab.
Then from the community, you can see Mosquitto. Install it. 
After installing, please stop the Mosquitto service before updating configuration. You can start service after changes.
Enable Admin login for Synology
Enable SSH in NAS
Download putty and connect to NAS Server
Login using admin 
Change to root user [sudo -i, {use admin password}]
Find mosquitto.conf file [find / -name mosquitto.conf]
Go to that path using cd [in my case cd /volume1/@appstore/mosquitto/var]
Edit mosquitto.conf [vi mosquitto.conf]
Might say it's used by another process. Force edit. 
Scroll down and find # allow_anonymous [around line 513]
Remove # and make [allow_anonymous false] [Use insert on keyboard to edit]
Scroll and find #password_file [around line 555]
Remove # and make password_file /volume1/@appstore/mosquitto/var/password_file [where 2nd password_file is the actual filename]
Save the file [Esc-> :wq to save]
Now create a file password_file in /volume1/@appstore/mosquitto/var/
Ensure your are still in same directory, type vi password_file 
This will create new file, press insert and type your username and password in below format
username:password [Username should not contain :]. You can add multiple users line by line 
Save file and clseo [Esc->:wq]
Find mosquitto_passwd [find / -name mosquitto_passwd]
Stay in the mosquitto.conf folder itself. Because we have password_file file here.
From mosquitto.conf folder, type mosquitto_passwd [along with path] -U password_file to encrypt password. 
In my case /volume1/@appstore/mosquitto/bin/mosquitto_passwd -U password_file
Start/restart Mosquitto Server
All done. Thank You.

Thank you all to all for the helpful snippets and hints. I am a noob when it comes to mosquitto and shell configuration files. My pitfall was definitely the configuration of the IP address and port on the listener. In my case, mosquitto.conf said listener 1883 127.0.0.1 and I had no access without an error message in the log. After I entered the IP address of my NAS there, it worked.

This did it for me!

Thanks for the detailed tutorial, my MQTT server is online