title: The License Callback Mechanism
created at: Thu Nov 28 2024 10:41:27 GMT+0000 (Coordinated Universal Time)
updated at: Sat Feb 08 2025 14:22:56 GMT+0000 (Coordinated Universal Time)
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# The License Callback Mechanism
# Overview
The license callback mechanism immediately updates a server after the license changes in either Manage2 or the cPanel Store. It cannot make any changes to the server. It **only** alerts the server that a change as been made to the license.
!! Note:
!! At least one port in the following table **must** be open for the license callback mechanism to work. The server only accepts requests to this API from cPanel & WHM. The license system does **not** send any other information to the customer’s server.
The license callback mechanism tries the following ports until one succeeds:
| Service | Port | Inbound | Outbound |
| ----------- | ------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------- |
| cPanel | `2082` |  | |
| cPanel SSL | `2083` |  | |
| WHM | `2086` |  | |
| WHM SSL | `2087` |  | |
| Webmail SSL | `2096` |  | |
The license callback mechanism uses the following IP addresses to perform the license check:
* `208.74.121.0/24`
* `208.74.123.0/24`
!! More:
!! For more information on how to configure your firewall for cPanel & WHM service, read our [documentation](https://docs.cpanel.net/knowledge-base/general-systems-administration/how-to-configure-your-firewall-for-cpanel-services/) .