1. Download the Win32 installer from the below link (I couldn’t successfully installed the CygWin version)
   https://mosquitto.org/download/
2. Once downloaded, install the package
3. During the start of the installation process it will show links from where some dependencies will have to be downloaded
   
4. Copy/Open the links
5. Once the installation finishes go to the websites opened in the previous step
6. Download the OpenSSL installer and the pthreadVC2.dll file
7. Install the OpenSSL
8. Copy the pthreadVC2.dll file to the directory where mosquitto executable has been installed. Normally C:\Program Files (x86)\mosquitto
9. Open folder where OpenSSL got installed (normally C:\OpenSSL\) and open the lib folder (normally C:\OpenSSL\lib)
10. Copy ssleay32.lib and libeay32.lib into the folder where mosquitto executable has been installed.
11. Please note – while copying the files Windows might ask for giving Admin permission. Go ahead.
12. At this point Mosquitto should be ready to run————————————————————–
13. Now testing mosquitto
14. Open a Command Prompt
15. Goto the folder where mosquitto is installed
16. Give command mosquitto.exe -v -c mosquitto.conf
17. The server should now start listening on port 1883
18. Now open another Command Prompt
19. Give the command mosquitto_sub -h localhost -t channel1/data1
20. Open a third Command Prompt and give the command mosquitto_pub -h localhost -t channel1/data1 -m “test data”
21. In the command prompt where we used mosquitto_sub (step 18 and 19) will show the message “test data” sent from the third command prompt.
22. Reaching this point means mosquitto is working fine———————————————-
23. To secure the transmission we can username and password authentication
24. Open a command prompt with Admin privileges
25. Goto the folder where Mosquitto is installed
26. Create a password file (for the first time only) using the command mosquitto_passwd.exe -c passfile.txt username
27. It will ask for password. Give the password and confirm the password
28. After this point further users can be added using the below command mosquitto_passwd.exe -b passfile.txt username password
    Please note – this time we supplied the password also along with the username
29. Now edit the config file (mosquitto.conf normally located in C:\Program Files (x86)\mosquitto) to enforce only authenticated data transfers
30. Uncomment allow_anonymous and set it false
31. Uncomment password_file and put the password file name after it. It will look like password_file passfile.txt
32. Now onwards all sub and pub requests will have to be with username and password of a user whose details exists in the password file. Examples below

    mosquitto_pub -h localhost -t channel1/data1 -m "test data" -u john -P johnpass 
    
    mosquitto_sub -h localhost -t channel1/data1 -u jane -P janepass

33. Access control can be done using a acl file or using mosquitto-auth-plug (https://github.com/jpmens/mosquitto-auth-plug)
34. There should be a aclfile.example inside your mqtt directory. If not then also no problem we will shortly see the contents of the file below.
35. Create a file with any name. Here we will use aclFile.txt
36. In the mosquitto.conf file uncomment acl_file and put the name of your acl file after that. It will look something like acl_file aclFile.txt
37. Example content of aclFile.txt as below

     # user jane given full permission to channel1/data1 and only read permission to channel1/data2
    user jane
    topic channel1/data1
    topic read channel1/data2
    
    # user jane given full permission to both data1 and data2 channel
    user john
    topic channel1/#

Please put in your suggestions in comment.

MQTT on Windows  — Download link of Word File containing the above steps. WordPress had made some filenames missing. So uploaded the original word doc.