Urgent Change the host url #12599

3 Answer(s)

• 

  0

  oguzhanagir created 8 months ago

  Support Team

  Hi @smartech

  To achieve both requirements in an ASP.NET Zero application using subdomain based multi tenancy, you can proceed as follows:

  Change the Host Subdomain (host → my)

  ASP.NET Zero determines the host tenant by bypassing specific subdomains in DomainTenantCheckMiddleware.

  Configuration

  Update your root address configuration to use your desired subdomain format:

  Web.Host/appsettings.json

  {
    "App": {
      "ServerRootAddress": "https://{TENANCY_NAME}.mydomain.xyz/"
    }
  }
  

  Web.Mvc/appsettings.json

  {
    "App": {
      "WebSiteRootAddress": "https://{TENANCY_NAME}.mydomain.xyz/"
    }
  }
  

  Middleware Update

  In DomainTenantCheckMiddleware.cs (*.Web.Core/MultiTenancy/DomainTenantCheckMiddleware.cs), add your custom host subdomain (my) to the bypass list:

  if (string.Equals(tenancyName, "www", StringComparison.OrdinalIgnoreCase))
  {
      await next(context);
      return;
  }
  
  if (string.Equals(tenancyName, "my", StringComparison.OrdinalIgnoreCase))
  {
      await next(context);
      return;
  }
  

  This ensures my.mydomain.xyz is treated as the host tenant.

  Handle Invalid Tenant Subdomains

  By default, ASP.NET Zero redirects non-existing tenant subdomains to the host. To prevent this behavior:

  Enable Invalid Tenant Protection

  In YourProjectNameConsts.cs (*.Core.Shared/YourProjectNameConsts.cs), set:

  public const bool PreventNotExistingTenantSubdomains = true;
  

  When enabled, DomainTenantCheckMiddleware will detect invalid tenants instead of silently redirecting to the host.

  Custom Error Handling

  If you prefer showing a custom page instead of the default redirect, update the middleware logic:

  if (tenantInfo == null)
  {
      context.Response.Redirect("/Error/TenantNotFound");
      return;
  }
  

  Then add a corresponding action in ErrorController:

  [Route("/Error/TenantNotFound")]
  public ActionResult TenantNotFound()
  {
      return View("TenantNotFound");
  }
  

  Alternatively, you may return a plain 404 response if you want to block access entirely.

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• 

  0

  smartech created 8 months ago

  How can we stop "host" to be used ? I mean if the user entered host.mydomain.xyz we need to response with an error instead of showing tenant not found

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• 

  0

  oguzhanagir created 8 months ago

  Support Team

  Hi @smartech

  In ASP.NET Zero, If you want to completely disable host.mydomain.xyz and return an error instead, you must explicitly block it in the tenant resolution middleware.

  Block host explicitly in DomainTenantCheckMiddleware

  Add the following check at the very beginning of DomainTenantCheckMiddleware.cs, before any bypass logic:

  *.Web.Core/MultiTenancy/DomainTenantCheckMiddleware.cs

  if (string.Equals(tenancyName, "host", StringComparison.OrdinalIgnoreCase))
  {
      context.Response.StatusCode = StatusCodes.Status404NotFound;
      await context.Response.WriteAsync("This subdomain is not allowed.");
      return;
  }
  

  This ensures that host.mydomain.xyz is never resolved as the Host Tenant.

  Allow only your custom host subdomain (my)

  Keep the bypass logic only for your custom host subdomain:

  if (string.Equals(tenancyName, "my", StringComparison.OrdinalIgnoreCase))
  {
      await next(context);
      return;
  }
  

  Enable invalid tenant protection

  Make sure this flag is enabled to prevent fallback to the host tenant:

  YourProjectNameConsts.cs

  public const bool PreventNotExistingTenantSubdomains = true;
  

  (Optional) Redirect to a custom error page

  Instead of returning a plain 404, you can redirect to a custom page:

  if (string.Equals(tenancyName, "host", StringComparison.OrdinalIgnoreCase))
  {
      context.Response.Redirect("/Error/SubdomainNotAllowed");
      return;
  }
  

  Block host at DNS / Reverse Proxy level as well

  Application level blocking is necessary, but for security and performance reasons, you can also implement host subdomain blocking at the DNS or reverse proxy layer.

  Prevents unnecessary requests from ever reaching your application Improves performance by short circuiting invalid traffic early

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