<PackageReference Include="System.Security.Permissions" Version="10.0.0-preview.2.25163.2" />

WebPermissionAttribute

Specifies permission to access Internet resources. This class cannot be inherited.
using System.Security; using System.Security.Permissions; namespace System.Net { [AttributeUsage(AttributeTargets.Assembly | AttributeTargets.Class | AttributeTargets.Struct | AttributeTargets.Constructor | AttributeTargets.Method, AllowMultiple = true, Inherited = false)] public sealed class WebPermissionAttribute : CodeAccessSecurityAttribute { public string Accept { get { return null; } set { } } public string AcceptPattern { get { return null; } set { } } public string Connect { get { return null; } set { } } public string ConnectPattern { get { return null; } set { } } public WebPermissionAttribute(SecurityAction action) : base(action) { } public override IPermission CreatePermission() { return null; } } }