azure

Automatically and securely mounting encrypted ZFS filesystems at boot with Azure Key Vault

The need for automation

As noted in my prior blogs, I use ZFS on Linux for my home fileserver and have been very impressed - it's been extremely stable, versatile and the command line utilities have simple syntax that work exactly as you'd expect them to.

A few months back native encryption was introduce into master branch for testing (you can read more here), and I have been using it to encrypt all my data. I chose not encrypt my root drive since it doesn't host any user data, and I do not want my boot to be blocked on password input - for example what if there's a power failure while I'm travelling for work?

However that still leaves two nagging problems:
1. It became tedious to manually SSH into my machine every time it restarts to type in numerous encrypted filesystem passphrases
2. A bunch of my systemd services depend on user data; issue in systemd (#8587) prevents using auto-generated mount dependenices to wait for the filesystems to be mounted so I have to start them menually.

Introducing zfs-keyvault

I decided to kill two birds with one stone and am happy to introduce zfs-keyvault, available on GitHub. It provides both a systemd service that can be depended upon by other services, as well automation for securely mounting encrypted ZFS filesystems.

On the client (with ZFS filesystems), a zkv utility is installed that can be used to manage an encrypted repository containing one or more ZFS filesystem's encryption keys. This repository is locally stored and its encryption key is placed in an Azure Key Vault.

On your preferred webhost or public cloud, a small Flask webserver called zkvgateway gates access to this repository key in Key Vault and can release under certain conditions.

On boot, the systemd service runs zkv which will reach out to the gateway, who in turn SMSs you with a PIN for approval. The inclusion of a PIN stops people from blindly hitting your endpoint to approve requests, and also prevents replay attacks. The gateway is also rate-limited to 1 request/s to stop brute-force attacks.

Once the PIN is confirmed over SMS, repository key is released from Azure Key Vault and the zkv utility can now decrypts the ZFS filesystem encryption keys which are locally stored, and begins mounting the filesystems. The filesystem encryption keys never leave your machine!

I've uploaded the server-side components as a Docker image named stewartadam/zkvgateway so it can be pulled and run easily. Enjoy!

Connecting Azure IoT Hub to Azure Functions and other Event-Hub compatible services

IoT Hub is a great, scalable way to manage your IoT devices. Did you know you can trigger an Azure Function when receiving a device-to-cloud message the same way you can for an Event Hub message?

Building the Event Hub connection string

Every IoT hub offers a read-only Event Hub-compatible endpoint that can be used with normal Event Hub consumers. This includes Azure Functions, which provides an Event Hub trigger.

You can view your IoT Hub's Event Hub-compatible by opening your IoT Hub resource in the Azure portal and navigating to the Endpoints blade, then clicking the Events (messages/events) endpoint. You will find the Event Hub-compatible name, and Event Hub-compatible endpoint (in the format of sb://iothub-ns-foo.servicebus.windows.net/) - keep note of these for later.

IoT Hub - Access Policy

Next, navigate to the IoT hub's Shared Access Policies blade. You will need to either use one of the existing policies or add your own, and the policy you choose must have the Service connect permission. Click any policy to view its associated primary key.

IoT Hub - Access Policy

Now, we can use these four pieces of information to construct an Event Hub connection string, which follows the format Endpoint=sb://EH_COMPATIBLE_ENDPOINT;EntityPath=EH_COMPATIBLE_NAME;SharedAccessKeyNa‌​me=IOTHUB_POLICY_NAME;Share‌​dAccessKey=IOTHUB_POLICY_KEY.

Configuring Azure Functions

We will now setup an Azure Function with a trigger using the Event Hub-compatible information.

Open the Azure Function resource and switch to the Integrate tab. Add a new trigger and choose Event Hub, which will reveal the following settings page:

Azure Functions - Trigger configuration

Enter the Event Hub-compatible name collected from IoT Hub earlier under Event Hub name and then press new to enter the Event Hub connection string derived earlier.

Azure Functions - Configure connection string

Lastly, we need to add code under the Develop tab with a parameter that matches the Event parameter name field, so use the following:

using System;

public static void Run(string myEventHubMessage, TraceWriter log)
{
    log.Info($"C# Queue trigger function processed: {myEventHubMessage}");
}

Testing the connection

Under the Function's Develop tab, click the Logs button from the toolbar to open the execution log. Next, send a cloud-to-device message -- if you haven't setup a device, simple_sample_device.js from the IoT Hub Node.js SDK does nicely.

After sending your message, you should see that your Function triggered successfully.

What about in ARM templates?

This manual setup is fine for testing, but what about automation for when moving to production?

ARM templates provide a reference() function that resolves a resource's runtime state. It's perfect for obtaining the Event Hub-compatible name that was provisioned as it was created:

    ...
    "parameters": {
        "iotHubName": {
            "defaultValue": "iothub2functions",
            "type": "String"
        }
    },
    "variables": {
        "iotHubApiVersion": "2016-02-03",
        "iotHubPolicyName": "service"
    },
    "outputs": {
        "eventHubConnectionString": {
            "type": "string",
            "value": "[concat('Endpoint=',reference(resourceId('Microsoft.Devices/IoTHubs',parameters('iotHubName'))).eventHubEndpoints.events.endpoint,';EntityPath=',reference(resourceId('Microsoft.Devices/IoTHubs',parameters('iotHubName'))).eventHubEndpoints.events.path,';SharedAccessKeyName=',variables('iotHubPolicyName'),';SharedAccessKey=',listKeys(resourceId('Microsoft.Devices/IotHubs/Iothubkeys', parameters('iotHubName'),variables('iotHubPolicyName')), variables('iotHubApiVersion')).primaryKey)]"
        }
    },
    ...

Getting started with the Skype for Business SDKs

The Skype for Business App SDK and Skype Web SDK are great ways to build the unified communication experience provided by the Skype for Business (previously Lync) server directly into web and mobile applications and deliver new interactive and collaborative experiences into your application.

If you're getting started with the Skype SDKs and/or Office 365 for the first time, the documentation available on the The Skype Developer Platform is a great place to start, but there are a number of steps you'll need to work through before coding.

In this post, I'll detail how to get setup with Skype for Business Online (Office 365) using a developer tenant and get coding as quickly as possible. As well, this is a good time to note that that at this time, some features of the SDKs are in preview. More features are coming out with every release!

Good to know: compatibility & platform features

As of writing (Jan. 2017), both the App SDK and Web SDK support connecting to on-premise and online (via Office 365) deployments.

However, at this time there are some important distinctions between the capabilities of the SDKs on the two platforms and in compatibility with O365 vs on-premise for meeting join. These differences will be rounded out in future SDK releases (for details on roadmap, see the Andrew Bybee's Ignite 2016 talk).

App SDK

The App SDK is available for iOS and Android apps, and supports the unauthenticated workflow. Meeting join, IM and audio-video communication is possible but done anonymously, using only a meeting link. There is no opportunity for a user to sign-in, so tasks like contact management are not available.

Web SDK

Contrary to the App SDK, the Web SDK has better support for authenticated workflows. Contact management, 1:1 conversations and more is available from the Web SDK after the user has authenticated. Anonymous meeting join, where the end-user joins a conference without signing in, is available but only when connecting to on-premise Skype for Business deployments at this time.

It's also important to note that both Chrome and Firefox have announced the deprecation of NPAPI plugins, which prevents the use of the Skype for Business Web App Plug-In. As such, audio-video functionality will be limited in Chrome and Firefox at this time.

IE11 and Safari both work with the web plug-in, and Edge supports A/V calling without any plugins via its built-in ORTC stack.

Setup an Office developer tenant

In order to get started, you'll need to be an administrator on Office 365 tenant and have 2-3 users that are licensed with Skype for Business. If you do not already have such an account, sign up at dev.office.com/devprogram to obtain a free Office developer account.

Once your account is activated, visit portal.office.com, click the Admin tile, then add 2-3 users and assign them a developer license.

App SDK

If you intent to build a mobile app, you are now ready to go - all you need is your app and a meeting link! Check out the meeting join samples for Android and iOS, and the App SDK documentation

You can generate a meeting link using the Skype for Business integration with Outlook, the desktop clients or the Lync Web Scheduler. To create them programtically, use the UCWA API. Meeting links follow the format https://meet.lync.com/tenant_name/organizer_username/meeting_id.

Web SDK

Because the Web SDK supports authenticated workflows, it requires some additional setup in order to authenticate users against Azure AD.

Creating an Azure AD Application

Registering an application will allow the Web SDK to perform OAuth authentication aginst users in an Azure AD directory. Previously, managing Azure AD applications required delving into the classic portal (instructions here) but fortunately Azure AD management is now available (in preview) in the new portal:

  1. Go to portal.azure.com
  2. Select Azure Active Directory > App registrations > Add
    Azure Portal - AAD
  3. Choose a human-readable name for your application and a unique sign-on URL. If unsure, use something like https://tenantID.onmicrosoft.com/appname - you can change it later once you move to production. Leave the type as Web app / API.

    Azure Portal - AAD - Create

  4. Select the Manifest button to open the manifest editor:

    Azure Portal - AAD - Manage

    Then set oauth2AllowImplicitFlow is set to true:

    Azure Portal - AAD - Manifest

  5. Next, navigate to the application's Properties blade and change Multi-tenanted to Yes. This will ensure that people outside of your Office tenant can use this application.

    Enabling multi-tenantancy on the application

  6. Navigate to the Reply URLs blade and enter the URLs at which your application will be hosted. Note that while developing your application, adding http://localhost is convinient but be aware that it means anyone who stands up their own site on http://localhost and knows your client ID can authenticate against your application. Tread carefully!

  7. Navigate to the Required Permissions blade and add delegated permissions for Skype for Business Online:

    Azure Portal - AAD - Permissions

    Azure Portal - AAD - Permissions 2

That's it - your application is now configured. However before it can authenticate users with the Web SDK, you must consent to the application using an admin user from your Office tenant. Open a In-Private/Incognito browsing window and visit this URL, replacing both CLIENT_ID and REDIRECT_URI as configured above: https://login.microsoftonline.com/common/oauth2/authorize?response_type=id_token&client_id=CLIENT_ID&redirect_uri=https://REDIRECT_URI&response_mode=form_post&nonce=...&resource=https://webdir.online.lync.com&prompt=admin_consent

Now check out the Web SDK documentation try running the Web SDK samples, or use the interactive Web SDK sample.