NT AUTHORITY\NETWORK SERVICE is not mapped in Sql Server. You have to do it by yourself. Network Service impersonates the computer account when trying to connect to an off-box resource. Granting permissions to DOMAIN\Servername$ does generally work.
Once the Sql Server mapping is created, you control permissions as for every others accounts. It's pretty the same.
Personnaly, I think it's not a good practice to mix integrated security & network service because it's a built-in account. It's probably ok for a lot of environments but you don't have a high degree of security. For example, if many web sites accessing the db are deployed in a Web Farm, you will completely loose control of permissions. It's also painfull to manage.
You have two options to avoid this :
This is relatively insecure. A disgruntled ex-employee could use the information maliciously, a visitor might see the code up on a screen somewhere or the source code might accidentally get out in the wild.
- Change application pool identity.
Simply create/reuse a separate Windows Account, grant it the minimum access it needs in SQL Server, and then change the application to run under the context of this new account.
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