# NGINX load balancer configuration with IIS authentication (Windows & anonymous authentication)

**URL:** <https://community.nginx.org/t/nginx-load-balancer-configuration-with-iis-authentication-windows-anonymous-authentication/6225>\
**Category:** NGINX\
**Tags:** auth, load-balancer, windows, config\
**Created:** [August 23, 2025, 4:19pm UTC](https://community.nginx.org/t/nginx-load-balancer-configuration-with-iis-authentication-windows-anonymous-authentication/6225 "2025-08-23T16:19:30Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![jayachandra21](https://drob5swvtjqxg.cloudfront.net/user_avatar/community.nginx.org/jayachandra21/32/2845_2.png) [@jayachandra21](https://community.nginx.org/u/jayachandra21)\
**Post date:** [August 23, 2025, 4:19pm UTC](https://community.nginx.org/t/nginx-load-balancer-configuration-with-iis-authentication-windows-anonymous-authentication/6225/1 "2025-08-23T16:19:30Z")

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_Please use this template for troubleshooting questions._

**My issue:**

**My application is hosted in the IIS webserver and it is running on Windows and anonymous authentication.** The application is hosted in the two nodes(server1 and server2) and NGINX is configured in Server3.

Now, with the NGINX, have configured the load balancer which point to two nodes.

In this case, when user runs the NGINX configured node3 portal user was getting the authentication screen. when user provided the authentication credentials it is not navigating to the application.

if user run the Individual application(let say server without NGINX) the with same user authentication it is working.

**Solutions I’ve tried:**

**NGINX** HTTP Load Balancing

**Deployment environment:**

Windows IIS

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**Author:** ![alessandro](https://drob5swvtjqxg.cloudfront.net/user_avatar/community.nginx.org/alessandro/32/4836_2.png) [@alessandro](https://community.nginx.org/u/alessandro)\
**Post date:** [August 24, 2025, 9:34pm UTC](https://community.nginx.org/t/nginx-load-balancer-configuration-with-iis-authentication-windows-anonymous-authentication/6225/2 "2025-08-24T21:34:39Z")

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Hey @jayachandra21! Do you know if you are using `ntlm` for authentication by any chance? If so, it’s only available when using NGINX Plus. If not, could you share your NGINX config?

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**Author:** ![jayachandra21](https://drob5swvtjqxg.cloudfront.net/user_avatar/community.nginx.org/jayachandra21/32/2845_2.png) [@jayachandra21](https://community.nginx.org/u/jayachandra21)\
**Post date:** [August 25, 2025, 7:21am UTC](https://community.nginx.org/t/nginx-load-balancer-configuration-with-iis-authentication-windows-anonymous-authentication/6225/3 "2025-08-25T07:21:47Z")

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Hello @alessandro ,

Yes, using the Windows Authentication.

I have attached the NGINX config file.

[NGINX Load Balacer Configuration.txt](https://community.nginx.org/uploads/short-url/7GlSAslqlPznrFBKfjuuzVPXPVQ.txt) (3.7 KB)

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<div class="post-metadata">

**Author:** ![alessandro](https://drob5swvtjqxg.cloudfront.net/user_avatar/community.nginx.org/alessandro/32/4836_2.png) [@alessandro](https://community.nginx.org/u/alessandro)\
**Post date:** [August 25, 2025, 1:52pm UTC](https://community.nginx.org/t/nginx-load-balancer-configuration-with-iis-authentication-windows-anonymous-authentication/6225/4 "2025-08-25T13:52:51Z")

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Like I mentioned, the issue is likely due to `ntlm` authentication not being available in NGINX Open Source.

You could potentially disable authentication on the Windows side and enable some level of user authentication in NGINX (see [Restricting Access with HTTP Basic Authentication | NGINX Documentation](https://docs.nginx.com/nginx/admin-guide/security-controls/configuring-http-basic-authentication/) or [Authentication Based on Subrequest Result | NGINX Documentation](https://docs.nginx.com/nginx/admin-guide/security-controls/configuring-subrequest-authentication/) for examples).

Otherwise, you will likely need to use NGINX Plus and use `ntlm` auth (you can request a free trial for NGINX One –which includes NGINX Plus– [here](https://www.f5.com/trials/nginx-one)).

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**Author:** ![system](https://drob5swvtjqxg.cloudfront.net/user_avatar/community.nginx.org/system/32/19_2.png) [@system](https://community.nginx.org/u/system)\
**Post date:** [September 24, 2025, 1:53pm UTC](https://community.nginx.org/t/nginx-load-balancer-configuration-with-iis-authentication-windows-anonymous-authentication/6225/5 "2025-09-24T13:53:34Z")

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