Prevent web_app.azurewebsites.net from being a usable URL and redirecting to the custom domain

Question

Prevent web_app.azurewebsites.net from being a usable URL and redirecting to the custom domain

Cavan Vannice 20

I'm finding that bots are hitting my azurewebsites.net domain name, and I want to prevent it and/or redirect it to my custom domain name. I don't see an easy way to do this in the app settings. Am I missing it?

Also, I pay for Azure support, but why am I not able to create a ticket on this? It forced me here.

Divyesh Govaerdhanan 11,725 Reputation points MVP Volunteer Moderator

2025-03-29T01:57:54.79+00:00
Hello,

Welcome to Microsoft Q&A,

Using URL rewrite, we can block the Azure Default domain with the following rule:

<rewrite> <rules> <rule name="Block default Azure Domain" stopProcessing="true"> <match url="(.*)" /> <conditions> <add input="{HTTP_HOST}" pattern="^(domainA.azurewebsites.net|domainB.azurewebsites.net)$" /> </conditions> <action type="CustomResponse" statusCode="403" statusReason="Forbidden" statusDescription="Site not accessible" /> </rule> </rules> </rewrite>

This rule will detect if the user has accessed the website using the Azure Default domain and issue a HTTP 403 forbidden status code.

This rule will not work if your website is behind a Proxy, Firewall, or other application gateways because the original host value may not be passed on to the WebApp service since we have this condition in the rule:

<conditions> <add input="{HTTP_HOST}" pattern="^(domainA.azurewebsites.net|domainB.azurewebsites.net)$" /> </conditions>

Please Upvote and Accept the answer if it helps!!
Shree Hima Bindu Maganti 7,585 Reputation points Microsoft External Staff Moderator

2025-04-09T08:34:32.82+00:00
Hi @Cavan Vannice
If you want to stop the web_app.azurewebsites.net domain from being used and direct traffic to your custom domain, make your custom domain the default for your Azure Static Web App. This way, any requests to the default domain will automatically go to your custom domain.

Here's how to set your custom domain as the default:

Open your static web app in the Azure portal.

Select Custom domains from the menu.

Pick the custom domain you want to set as the default.

Click on Set default.

Once it's done, refresh the table to make sure your domain is marked as "default".

To block access to the default domain completely, submit a support ticket. Just make sure your custom domain is working fine before doing this, as it could disable some features.

If you have trouble creating a support ticket, check your Azure subscription settings or reach out to Azure support through their official channels.
Manage the default domain in Azure Static Web Apps

Blocking the default domain
Let me know if you have any further assistances.
Shree Hima Bindu Maganti 7,585 Reputation points Microsoft External Staff Moderator

2025-04-10T14:07:34.4666667+00:00

Hi @Cavan Vannice
following up to see if you had chance to review my previous response and help us with requested information to check and assist you further on this.
Shree Hima Bindu Maganti 7,585 Reputation points Microsoft External Staff Moderator

2025-04-11T08:54:29.0966667+00:00

Hi @Cavan Vannice
following up to see if you had chance to review my previous response and help us with requested information to check and assist you further on this.
Cavan Vannice 20 Reputation points

2025-04-18T19:17:26.5633333+00:00

I am running the site within a docker container, where would I put the web.config file?
Cavan Vannice 20 Reputation points

2025-04-18T19:18:51.9733333+00:00

This is azure app service, not a static site. I do not see a way to set a default domain in azure app service
Cavan Vannice 20 Reputation points

2025-04-18T19:21:08.6266667+00:00

For some reason, I didn't get emails when answers were posted to this question. Sorry :(

Your answer

Divyesh Govaerdhanan 11,725 Reputation points MVP Volunteer Moderator

2025-03-29T01:57:54.79+00:00

Hello,

Welcome to Microsoft Q&A,

Using URL rewrite, we can block the Azure Default domain with the following rule:

<rewrite> <rules> <rule name="Block default Azure Domain" stopProcessing="true"> <match url="(.*)" /> <conditions> <add input="{HTTP_HOST}" pattern="^(domainA.azurewebsites.net|domainB.azurewebsites.net)$" /> </conditions> <action type="CustomResponse" statusCode="403" statusReason="Forbidden" statusDescription="Site not accessible" /> </rule> </rules> </rewrite>

This rule will detect if the user has accessed the website using the Azure Default domain and issue a HTTP 403 forbidden status code.

This rule will not work if your website is behind a Proxy, Firewall, or other application gateways because the original host value may not be passed on to the WebApp service since we have this condition in the rule:

<conditions> <add input="{HTTP_HOST}" pattern="^(domainA.azurewebsites.net|domainB.azurewebsites.net)$" /> </conditions>

Please Upvote and Accept the answer if it helps!!
Shree Hima Bindu Maganti 7,585 Reputation points Microsoft External Staff Moderator

2025-04-09T08:34:32.82+00:00

Hi @Cavan Vannice
If you want to stop the web_app.azurewebsites.net domain from being used and direct traffic to your custom domain, make your custom domain the default for your Azure Static Web App. This way, any requests to the default domain will automatically go to your custom domain.

Here's how to set your custom domain as the default:

Open your static web app in the Azure portal.

Select Custom domains from the menu.

Pick the custom domain you want to set as the default.

Click on Set default.

Once it's done, refresh the table to make sure your domain is marked as "default".

To block access to the default domain completely, submit a support ticket. Just make sure your custom domain is working fine before doing this, as it could disable some features.

If you have trouble creating a support ticket, check your Azure subscription settings or reach out to Azure support through their official channels.
Manage the default domain in Azure Static Web Apps

Blocking the default domain
Let me know if you have any further assistances.
Shree Hima Bindu Maganti 7,585 Reputation points Microsoft External Staff Moderator

2025-04-10T14:07:34.4666667+00:00

Hi @Cavan Vannice
following up to see if you had chance to review my previous response and help us with requested information to check and assist you further on this.
Shree Hima Bindu Maganti 7,585 Reputation points Microsoft External Staff Moderator

2025-04-11T08:54:29.0966667+00:00

Hi @Cavan Vannice
following up to see if you had chance to review my previous response and help us with requested information to check and assist you further on this.
Cavan Vannice 20 Reputation points

2025-04-18T19:17:26.5633333+00:00

I am running the site within a docker container, where would I put the web.config file?
Cavan Vannice 20 Reputation points

2025-04-18T19:18:51.9733333+00:00

This is azure app service, not a static site. I do not see a way to set a default domain in azure app service
Cavan Vannice 20 Reputation points

2025-04-18T19:21:08.6266667+00:00

For some reason, I didn't get emails when answers were posted to this question. Sorry :(