Posted on

CS1617: Invalid option ‘6’ for /langversion; must be ISO-1, ISO-2, 3, 4, 5 or Default

Compiler Error CS1617

Invalid option ‘option’ for /langversion. Use ‘/langversion:?’ to list supported values.

For example

Invalid option ‘6’ for /langversion; must be ISO-1, ISO-2, 3, 4, 5 or Default


Right click on your project and select “Properties” from menu.

Select Build menu and, in the bottom, click on button “Advanced”.

In the next form you don’t have any voice for the field “Language Version”

Select “default”


Posted on

How to check the execution of Microsoft Agent Backup

To check the outcome of Microsoft Azure Backup execution we can take advantage of the fact that, if the backup fails, some events are generated.

Prepare script to send email

Copy and paste the following code in a new file and modify it with your data (mail server, user, password, messages).

$SMTPPort = "25"
$Password = "PASSWORD"

$to = "Email recipient"
# $cc = "cc email recipient"
$subject = "Error Backup MyServer"
$body = "backup failed"
# $attachment = ""

$message = New-Object System.Net.Mail.MailMessage
$message.subject = $subject
$message.body = $body
# $$cc)
$message.from = $username
# $message.attachments.add($attachment)

$smtp = New-Object System.Net.Mail.SmtpClient($SMTPServer, $SMTPPort);
$smtp.EnableSSL = $true
$smtp.Credentials = New-Object System.Net.NetworkCredential($Username, $Password);
write-host "Mail Sent"

Save it as file with extension .ps1

Creating a new Task

  1. Open the Task Scheduler : Control Panel -> Administrative Tools -> Task Scheduler
  2. Right-click the “Task Scheduler Library” branch, and select the New Folder option.
  3. Type a name for the folder. For example, MyTasks.
  4. Expand the “Task Scheduler Library” branch, and select the MyTasks folder.
  5. Click the Action menu.
  6. Select the Create Task option.

Task to check Azure Backup

  1. In the Name field you can write something like “Check Micrososft Agent Backup”.
  2. Click the Triggers tab.
  3. Click the New button.
  4. Use the “Begin the task” drop-down menu to select “On a Event”
  5. Click custom option under the Settings section.

  1. Click the Edit Event Filter… button.
  2. Go the XML tab and at the bottom of the menu press the edit query manually button.
  3. Copy and paste the below XML and OK the changes.
<Query Id="0" Path="CloudBackup">
<Select Path="CloudBackup">*[System[(Level=1 or Level=2) and (EventID=5 or EventID=10 or EventID=11 or EventID=12 or EventID=13 or EventID=14 or EventID=16 or EventID=18)]]</Select>
  1. Click the Actions tab.
  2. Click the New button.
  3. Browse on the previous powershel script
  4. Clicck OK to save the task

From now on, an email should be sent to you when the backup fails.

Posted on

c# and shadow copy – notes on library AlphaVSS


AlphaVSS is a .NET class library providing a managed API for the Volume Shadow Copy Service also known as VSS

Error loading library AlphaVSS.x64.dll

if you have error loading the library probabilly you need to install on the machine the Visual C++ 2017 Redist package.

You can find it at this link

Control shadow copy

To control shadow copy, created using alphavss library, you have to open a command prompt whith administrative priviliges and type


to list your shadow copy you have to type :

vssadmin list shadows


Posted on

Configure a Point-to-Site VPN connection via Openvpn on Azure

Create a virtual network

  1. Sign in to the Azure portal.
  2. In Search resources, service, and docs , type virtual network.
  3. On the Virtual Network page, select Create.
  4. On the IP Addresses tab, configure the values

Subnet: If you use the default address space, a default subnet is created automatically.

  • Subnet name: In this example, we named the subnet “FrontEnd”.
  • Subnet address range: The address range for this subnet.

On the Security tab, at this time, leave the default values:

  • DDos protection: Basic
  • Firewall: Disabled

So we will have this configuration (as example) :

  • Address space:
    Subnet name: FrontEnd
  • Subnet address range:

Create a virtual network gateway

  1. In the Search the Marketplace field, type ‘Virtual Network Gateway’

SKU: Select the gateway SKU from the dropdown. For Openvpn you need to select VpnGw1 because

Gateway subnet address range: This field only appears if your VNet doesn’t have a gateway subnet. If possible, make the range /27 or larger (/26,/25 etc.)

In this example :



Certificates are used by Azure to authenticate clients connecting to a VNet over a Point-to-Site VPN connection. You have two options : use a root certificate that was generated with an enterprise solution (recommended), or generate a self-signed certificate.

Generate and export certificates for Point-to-Site using PowerShell

Two steps : generate root certificate; generate client certificate.

root certificate

From a computer running Windows 10 or Windows Server 2016, open a Windows PowerShell console in Admin mode.

Use the following example to create the self-signed root certificate. The following example creates a self-signed root certificate named ‘TestVPNRootCert’ that is automatically installed in ‘Certificates-Current User\Personal\Certificates’.

$cert = New-SelfSignedCertificate -Type Custom -KeySpec Signature -Subject "CN=TestVPNRootCert" -KeyExportPolicy Exportable -HashAlgorithm sha256 -KeyLength 2048 -CertStoreLocation "Cert:\CurrentUser\My" -KeyUsageProperty Sign -KeyUsage CertSign

You can view the certificate by opening certmgr.msc, or Manage User Certificates.

client certificate

Each client computer that connects to a VNet using Point-to-Site must have a client certificate installed. You generate a client certificate from the self-signed root certificate.

From a computer running Windows 10 or Windows Server 2016, open a Windows PowerShell console in Admin mode. Identify the self-signed root certificate that is installed on the computer. This cmdlet returns a list of certificates that are installed on your computer.

Get-ChildItem -Path "Cert:\CurrentUser\My"

As output you will see a string and a name for every certificate installed on your machine.

For example :

AED812AD883826FF76B4D1D5A77B3C08EFA79F3F CN=MyOldVPNRootCert

7181AA8C1B4D34EEDB2F3D3BEC5839F3FE52D655 CN=TestVPNRootCert

Declare a variable for the root certificate using the string from the previous step:

$cert = Get-ChildItem -Path “Cert:\CurrentUser\My\7181AA8C1B4D34EEDB2F3D3BEC5839F3FE52D655”

Modify and run the example to generate a client certificate. The result of the following example is a client certificate named ‘TestVPNClientCert’

New-SelfSignedCertificate -Type Custom -DnsName TestVPNClientCert -KeySpec Signature  -Subject "CN=TestVPNClientCert" -KeyExportPolicy Exportable  -HashAlgorithm sha256 -KeyLength 2048  -CertStoreLocation "Cert:\CurrentUser\My"  -Signer $cert -TextExtension @("{text}")

The client certificate that you generate is automatically installed in ‘Certificates – Current User\Personal\Certificates’ on your computer.

Export the root certificate public key (.cer)

To obtain a .cer file from the certificate, open Manage user certificates. Locate the self-signed root certificate, typically in ‘Certificates – Current User\Personal\Certificates’, and right-click. Click All Tasks, and then click Export. This opens the Certificate Export Wizard.

Select No, do not export the private key, and then click Next

On the Export File Format page, select Base-64 encoded X.509 (.CER)., and then click Next.

For File to ExportBrowse to the location to which you want to export the certificate. For File name, name the certificate file. Then, click Next.

Click Finish to export the certificate. You’ll find a file .cer in location selected.

Export the client certificate

To export a client certificate, open Manage user certificates. The client certificates that you generated are, by default, located in ‘Certificates – Current User\Personal\Certificates’. Right-click the client certificate that you want to export, click all tasks, and then click Export to open the Certificate Export Wizard.

Select Yes, export the private key, and then click Next. IMPORTANT!!!!

On the Export File Format page, leave the defaults selected. Make sure that Include all certificates in the certification path if possible is selected

On the Security page, you must protect the private key, using a password.

On the File to ExportBrowse to the location to which you want to export the certificate. For File name, name the certificate file. Then, click Next.Click Finish to export the certificate.

Add the client address pool

The client address pool is a range of private IP addresses that you specify. The clients that connect over a Point-to-Site VPN dynamically receive an IP address from this range. Use a private IP address range that does not overlap with the on-premises location that you connect from, or the VNet that you want to connect to.

Open virtual network gateway configuration page, navigate to the Settings section of the virtual network gateway page. In the Settings section, select Point-to-site configuration. Select Configure now to open the configuration page.

In the Address pool box, add the private IP address range that you want to use. VPN clients dynamically receive an IP address from the range that you specify.

For example :

Tunnel Type : OpenVpn

Authentication Type : Azure certificate

In root certificate section you have to put the root certificate name (in this example TestVPNRootCert).

Open the root certificate file (.cer) with a text editor, such as Notepad. Copy the text as in image and past it in “Public certificate data”

Save Point to Site Configuration.

Download vpn Client clicking on “Download vpn Client” 🙂

Install Openssl

Extract the private key and the base64 thumbprint from the .pfx client certificate.

Using OpenSSL on your machine is one way. The profileinfo.txt file contains the private key and the thumbprint for the CA and the Client certificate

openssl pkcs12 -in “C:\myfolder\clientcert_vpn_test.pfx” -nodes -out “C:\myfolder\profileinfo.txt”

Configure openvpn client

Unzip the profile downloaded from virtual network point to site configuration. Next, open the vpnconfig.ovpn configuration file from the OpenVPN folder using Notepad. Open profileinfo.txt in Notepad and copy and paste in vpnconfig.ovpn the sections :

# P2S client certificate
# please fill this field with a PEM formatted cert
# P2S client root certificate private key
# please fill this field with a PEM formatted key

IMPORTANT :certificate and kay need to be insert in  openvpncon with  —- begin — and —-end —–


Posted on

Authentication Developing for Azure Media Service

After creation of your Azure Media Service (AMS) Account (Create a Media Services account using the Azure portal) you need to authenticate your application that your are developing , to manage your video and streaming channels.

Developing with .net

In this article we are using .net framework to develop an app, but the information should be valid for all languages.

To develop an application with .net frameeork, you need to install, via nuget , the package windowsazure.mediaservices.extensions with its derived packages.

You can authenticate in one of two ways :

User authentication

Authenticates a person who is using the app to interact with Azure Media Services resources. The interactive application should first prompt the user for credentials.

For this authentication your app needs two strings :

Azure AD tenant  (“tenant” in example) :  In Azure portal, select your AMS and  select, on the left menu, api page. In the table at the bottom of the page one of the fields is “Domain Tenant ADD”.

Endpoint API REST (“endpoint” in example) : you can read this information directly in main page of your AMS on the right at the top of the page. Should be something like this :

In your application you have to write this code :

var tokenCredentials = new AzureAdTokenCredentials(tenant, AzureEnvironments.AzureCloudEnvironment);
var tokenProvider = new AzureAdTokenProvider(tokenCredentials);
_context = new CloudMediaContext(new Uri(endpoint), tokenProvider);

Running the application you should automatically see the Microsoft user credentials form


Service principal authentication

Authenticates a service, a specific app, without user interaction. To use this authenticaton in your app, you need four strings :

Azure AD tenant  (“tenant” in example) : As above

Endpoint API REST (“endpoint” in example) : As above

Client ID (“clientid” in example) : Enter in azure portal and look for “applications”. Add new application. After creation, in properties, at the top of the page, you can find the “application ID”.

Client Secret (“secretid” in example): in your AMS select the API page. In the middle of page you can find a little form with two fields. In the first field you ha to select the application created before. Use the second field to create the client secret.

In your application you have to write this code :

AzureAdTokenCredentials tokenCredentials =
new AzureAdTokenCredentials(tenant,
new AzureAdClientSymmetricKey(_clientid, _secreteid),

var tokenProvider = new AzureAdTokenProvider(tokenCredentials);

_context = new CloudMediaContext(new Uri(endpoint), tokenProvider);
Posted on

Token based authentication in ASP.NET Web API

Token based authentication

Nella “Token based authentication”, l’applicazione client invia prima una richiesta all’endpoint del server di autenticazione con le credenziali dell’utente; se il nome utente e la password sono corretti, il server di autenticazione invia un token al client come risposta. Questo token contiene dati sufficienti per identificare un determinato utente e un tempo di scadenza. L’applicazione client utilizza quindi il token per accedere alle risorse nelle richieste successive fino a quando il token risulta ancora valido (non scaduto).

Classe per validare le richieste del client

Aggiungete una classe come questa :

using Microsoft.Owin.Security.OAuth;
using System.Security.Claims;
using System.Threading.Tasks;
using Microsoft.AspNet.Identity.Owin;

namespace Mysite.Helpers
    public class MysiteAuthorizationServerProvider : OAuthAuthorizationServerProvider
        public override async Task ValidateClientAuthentication(OAuthValidateClientAuthenticationContext context)
            context.Validated(); // 

        public override async Task GrantResourceOwnerCredentials(OAuthGrantResourceOwnerCredentialsContext context)
            var userManager = context.OwinContext.GetUserManager<ApplicationUserManager>();
            var user = await userManager.FindAsync(context.UserName, context.Password);
            if (user == null)
                context.SetError("invalid_grant", "The user name or password is incorrect.");
            ClaimsIdentity oAuthIdentity = await user.GenerateUserIdentityAsync(userManager,


Per attivare questa classe andate nel file App_Start/Startup.Auth.cs e aggiungete alla fine del metodo ConfigureAuth questo codice

var myProvider = new  MysiteAuthorizationServerProvider();
            OAuthAuthorizationServerOptions options = new OAuthAuthorizationServerOptions
                AllowInsecureHttp = true,
                TokenEndpointPath = new PathString("/token"),
                AccessTokenExpireTimeSpan = TimeSpan.FromDays(1),
                Provider = myProvider
            app.UseOAuthBearerAuthentication(new OAuthBearerAuthenticationOptions());

In cui si definisce il link http://mysite/token che restituisce un token di durata 1 giorno.

Dovrete aggiungere nel file il riferimento

using Microsoft.Owin.Security.OAuth;

E’ necessario aggiungere un metodo all’autenticazione. Andate nel file IdentityModel.cs e aggiungete questo metodo :

public async Task<ClaimsIdentity> GenerateUserIdentityAsync(UserManager<ApplicationUser> manager,
            string authenticationType)
           var userIdentity = await manager.CreateIdentityAsync(this, authenticationType);
           return userIdentity;


Per testare il tutto facilmente potete usare Postman .

Dovrete creare con Postman una chiamata post sul vostro link http://mysite/token. Nell’headers inserite la dicitura che vedete in figura :

Nel Body inserite il tipo di autneticazione (password) il vostro username e la vostra password.

Spingete “Send”. Se tutto ha funzionato riceverete il token

Utilizzo del Token

Una volta che il client ha ricevuto il token lo può utilizzare per tutte le successive operazioni senza dover passare lo username e la password: va passato solo il token che contiene queste informazioni. Facciamo una prova, creando un metodo che richiede autenticazione all’interno di un controller :

using System;
using System.Web.Http;

namespace MySite.Controllers
    public class SampleController : ApiController
        public IHttpActionResult GetForAuthenticate()
            var identity = (ClaimsIdentity)User.Identity;
            return Ok("Hello " + identity.Name);

Usando postman, fate una chiamata GET al link : http://MySite/api/Sample/GetForAuhenticate

Dovrete passare al link il token che avete ottenuto qualche istante prima (nel nostro esempio è valido per 1 giorno). Per farlo in postman aggiungete la chiave Authorization con valore la parola Bearer seguita dal token.


Posted on

add Web API to an mvc site

Install the Web API Client Libraries

Use NuGet Package Manager to install the Web API Client Libraries package :

  • Microsoft.AspNet.WebApi.Client
  • Microsoft.AspNet.WebApi.Core
  • Microsoft.AspNet.WebApi.WebHost

Define a Web API Routing Configuration

Add App_Start\WebApiConfig.cs

using System.Web.Http;

class WebApiConfig
    public static void Register(HttpConfiguration configuration)
                name: "DefaultApi",
                routeTemplate: "api/{controller}/{action}/{id}",
                defaults: new { id = RouteParameter.Optional }

Register the WebAPI Routing Configuration

If you added a new WebApiConfig.cs file, you need to register that on your Web Application’s main configuration class.

Import namespace System.Web.Http in Global.asax.cs.

Add this line before the registration of your classic routing

//api routing (before)
//existing normal route

Create a sample Web API Controller

Create a new controller

using System;
using System.Web.Http;

namespace MySite.Controllers
    public class SampleController : ApiController
       public String Test()
         return "Hello World!";

Based on the api routing you should call this method in your browser using


with this result

<string xmlns=””>Hello World!</string>