How to Set your Minecraft Server to Offline Mode

In order to allow offline-mode players to enter your server (often referred to as "cracked" players), it is necessary to edit the server's "server.properties" file to disable the online-mode parameter.

BEFORE DISABLING ONLINE MODE:
Disabling online mode means that your server will no longer use Mojang authentication for Minecraft accounts.
This means that players using cracked Minecraft clients can join your server. By using these clients, players can get whatever username they want. This can cause problems when banning players from your server as they can rejoin under another name.

If you use plugins or mods on your server, you may experience a player data reset when switching from online mode to offline mode.

These are the steps to follow:

1. Go to your server's control panel.

2. Click on the server you want to set to offline mode.

3. Click on the "Configuration" button. 

4. Click on the  "Server Properties" button.

5. Find the "Online mode" parameter.

6. Select the "False" option.

7. Click on the "Save" button at the bottom of the page.

8. Restart your server.

The server can now be accessed by both online and offline mode players.