WebRequest.create在.NET 3.5类库中引起SecurityException，但在.net 4.5中不引起

Question

The following code breaks in a .NET 3.5 class library project, but not in .net 4. I'm stumped and would appreciate any ideas:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Text;
using NUnit.Framework;

namespace test2
{

[TestFixture]
public class TestClass
{
    [Test]
    public void Test()
    {
        var request =
             WebRequest.Create("http://www.google.com");

Specific Exception:

System.Security.SecurityException : Request for the permission of type 'System.Net.WebPermission, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed.
   at System.Security.CodeAccessSecurityEngine.Check(Object demand, ref StackCrawlMark stackMark, Boolean isPermSet)
   at System.Security.CodeAccessPermission.Demand()
   at System.Net.HttpWebRequest..ctor(Uri uri, ServicePoint servicePoint)
   at System.Net.HttpRequestCreator.Create(Uri Uri)
   at System.Net.WebRequest.Create(Uri requestUri, Boolean useUriBase)
   at System.Net.WebRequest.Create(String requestUriString)
   at test2.LaunchRequestInitializeIdsTestFixture.Test()

Answer 1

The answer, as the exception says, is Code Access Security (CAS). I am building my code from a network drive (hosted VM). In .NET 3.5 and below, the network drive has lower privileges. This restriction was turned off for .NET 3.5 SP1 and above. The following link put me on the right track: http://blogs.msdn.com/b/vancem/archive/2008/08/13/net-framework-3-5-sp1-allows-managed-code-to-be-launched-from-a-network-share.aspx

The following, run from caspol in the .NET 2 install dir got my code working:
caspol.exe -m -pp off -ag 1 -url "file:///Z:/*" FullTrust

I got the above command line from this helpful post: https://julianscorner.com/wiki/programming/caspol_network_share

FYI: to restore to defaults, just run "caspol -restore"