# NTLM Authentication

NTLM (NT LAN Manager) authentication is a Microsoft proprietary authentication protocol used to authenticate users in a Windows-based network.

It provides secure authentication by using a challenge-response mechanism, where the server sends a challenge to the client, and the client sends a response that is encrypted using a hash of the user’s password.

NTLM authentication is used in various Microsoft products, including Windows, Internet Explorer, and Microsoft Office.

### NTLM in Astera

Astera also offers the ability to use NTLM authentication when establishing an API connection.

1. To start, drag-and-drop the *API Connection* object from the Toolbox onto a Dataflow.

![](/files/ULRJVeOOJ7XRAYqkrqcG)

2. Right-click on the object and select *Properties* from the context menu.

This will open a new window,

![](/files/VLMe2WBWPdYV3HWtQqNE)

*Base URL:* Here, you can specify the base URL of the API which will prepend as a common path to all API endpoints sharing this connection. A Base URL usually consists of the scheme hostname and port of the API web address.

*Timeout (msec):* Specify the duration, in milliseconds, to wait for the API server to respond before giving a timeout error.

*Include Client SSL Certificate:* Selecting this option is going to include any Client SSL certificate that is needed for authentication.

*Enable Authentication Logs:* Selecting this checkbox will allow the client to generate authentication logs when the API connection has been configured.

3. Fill in the Base URL and open the *Security Type* drop-down menu,

For our use case, we have deployed an API on IIS Manager on another machine, and we will send a request to access that API.

4. Select *NTLM* as the authentication type.

This will give us the following options,

![](/files/RHrxRyASOjlvWBt39Hbh)

*Username:* This field will input the same username that is used to login to Windows.

*Password:* The password associated with Windows login credentials.

{% hint style="info" %}
**Note:** NTLM authentication establishes API connections using a challenge-response mechanism. When sending an API request, Astera sends a hashed version of the user’s credentials (username and password) to the server, which sends back a random challenge. Astera then mixes this challenge with the user’s password and sends back a hashed value for verification. Access is granted if the validation is successful.
{% endhint %}

5. Click *OK* and the *API Connection* object will be configured with NTLM Authentication.

![](/files/xw6pTxKWNbd8XzDd5jyU)

This *API Connection* can then be used in *API Client* objects to make API calls to the server and receive appropriate responses in return.

6. Drag-and-drop an *API Client* object onto the dataflow and select the shared connection that was defined.

![](/files/5VKwNs52CnPu2k8iSSl4)

{% hint style="info" %}
**Note:** The *Resource* will be ‘/’ since our entire address has been defined in the *Base URL*.
{% endhint %}

![08-Resource](/files/Ccvx7ai43kvLvPGbWkFe)

7. Click *OK* and preview the output of the *API Client* object.

As we can see in our data preview window, the request has been sent successfully and the response has returned as ‘200 OK’.

![](/files/TB7mzPgTd5N8CTY0WVna)

This concludes working with and configuring the NTLM Authentication in Astera.


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