diff --git a/SMBLibrary/Server/SMB2/IOCtlHelper.cs b/SMBLibrary/Server/SMB2/IOCtlHelper.cs
index 3200a26..860a378 100644
--- a/SMBLibrary/Server/SMB2/IOCtlHelper.cs
+++ b/SMBLibrary/Server/SMB2/IOCtlHelper.cs
@@ -17,33 +17,44 @@ namespace SMBLibrary.Server.SMB2
         internal static SMB2Command GetIOCtlResponse(IOCtlRequest request, ISMBShare share, SMB2ConnectionState state)
         {
             SMB2Session session = state.GetSession(request.Header.SessionID);
+            string ctlCode = Enum.IsDefined(typeof(IoControlCode), request.CtlCode) ? ((IoControlCode)request.CtlCode).ToString() : ("0x" + request.CtlCode.ToString("x"));
+            if (!request.IsFSCtl)
+            {
+                // [MS-SMB2] If the Flags field of the request is not SMB2_0_IOCTL_IS_FSCTL the server MUST fail the request with STATUS_NOT_SUPPORTED.
+                state.LogToServer(Severity.Verbose, "IOCTL: Non-FSCTL requests are not supported. CTL Code: {0}", ctlCode);
+                return new ErrorResponse(request.CommandName, NTStatus.STATUS_NOT_SUPPORTED);
+            }
+
             if (request.CtlCode == (uint)IoControlCode.FSCTL_DFS_GET_REFERRALS ||
                 request.CtlCode == (uint)IoControlCode.FSCTL_DFS_GET_REFERRALS_EX)
             {
                 // [MS-SMB2] 3.3.5.15.2 Handling a DFS Referral Information Request
+                state.LogToServer(Severity.Verbose, "IOCTL failed. CTL Code: {0}. NTStatus: STATUS_FS_DRIVER_REQUIRED.", ctlCode);
                 return new ErrorResponse(request.CommandName, NTStatus.STATUS_FS_DRIVER_REQUIRED);
             }
 
-            OpenFileObject openFile = session.GetOpenFileObject(request.FileId);
             object handle;
-            if (openFile == null)
+            if (request.CtlCode == (uint)IoControlCode.FSCTL_PIPE_WAIT ||
+                request.CtlCode == (uint)IoControlCode.FSCTL_VALIDATE_NEGOTIATE_INFO ||
+                request.CtlCode == (uint)IoControlCode.FSCTL_QUERY_NETWORK_INTERFACE_INFO)
             {
-                if (request.CtlCode == (uint)IoControlCode.FSCTL_PIPE_WAIT ||
-                    request.CtlCode == (uint)IoControlCode.FSCTL_VALIDATE_NEGOTIATE_INFO ||
-                    request.CtlCode == (uint)IoControlCode.FSCTL_QUERY_NETWORK_INTERFACE_INFO)
+                // [MS-SMB2] 3.3.5.15 - FSCTL_PIPE_WAIT / FSCTL_QUERY_NETWORK_INTERFACE_INFO /
+                // FSCTL_VALIDATE_NEGOTIATE_INFO requests MUST have FileId set to 0xFFFFFFFFFFFFFFFF.
+                if (request.FileId.Persistent != 0xFFFFFFFFFFFFFFFF || request.FileId.Volatile != 0xFFFFFFFFFFFFFFFF)
                 {
-                    // [MS-SMB2] 3.3.5.1.5 - FSCTL_PIPE_WAIT / FSCTL_QUERY_NETWORK_INTERFACE_INFO /
-                    // FSCTL_VALIDATE_NEGOTIATE_INFO requests have FileId set to 0xFFFFFFFFFFFFFFFF.
-                    handle = null;
-                }
-                else
-                {
-                    state.LogToServer(Severity.Verbose, "IOCTL failed. Invalid FileId.");
-                    return new ErrorResponse(request.CommandName, NTStatus.STATUS_FILE_CLOSED);
+                    state.LogToServer(Severity.Verbose, "IOCTL failed. CTL Code: {0}. Invalid FileId.", ctlCode);
+                    return new ErrorResponse(request.CommandName, NTStatus.STATUS_INVALID_PARAMETER);
                 }
+                handle = null;
             }
             else
             {
+                OpenFileObject openFile = session.GetOpenFileObject(request.FileId);
+                if (openFile == null)
+                {
+                    state.LogToServer(Severity.Verbose, "IOCTL failed. CTL Code: {0}. Invalid FileId.", ctlCode);
+                    return new ErrorResponse(request.CommandName, NTStatus.STATUS_FILE_CLOSED);
+                }
                 handle = openFile.Handle;
             }
 
@@ -52,11 +63,11 @@ namespace SMBLibrary.Server.SMB2
             NTStatus status = share.FileStore.DeviceIOControl(handle, request.CtlCode, request.Input, out output, maxOutputLength);
             if (status != NTStatus.STATUS_SUCCESS && status != NTStatus.STATUS_BUFFER_OVERFLOW)
             {
-                state.LogToServer(Severity.Verbose, "IOCTL failed. CTL Code: 0x{0}. NTStatus: {1}.", request.CtlCode.ToString("x"), status);
+                state.LogToServer(Severity.Verbose, "IOCTL failed. CTL Code: {0}. NTStatus: {1}.", ctlCode, status);
                 return new ErrorResponse(request.CommandName, status);
             }
 
-            state.LogToServer(Severity.Verbose, "IOCTL succeeded. CTL Code: 0x{0}.", request.CtlCode.ToString("x"));
+            state.LogToServer(Severity.Verbose, "IOCTL succeeded. CTL Code: {0}.", ctlCode);
             IOCtlResponse response = new IOCtlResponse();
             response.Header.Status = status;
             response.CtlCode = request.CtlCode;