Pay in the future should make you think in the present

BuckWoody — Tue, 10 Apr 2012 13:53:50 GMT

Distributed Computing - and more importantly “-as-a-Service” models of computing have a different cost model. This is something that sounds obvious on the surface but it’s often forgotten during the design and coding phase of a project.

In on-premises computing, we’re used to purchasing a server and all of the hardware infrastructure and software licenses needed not only for one project, but several. This is an up-front or “sunk” cost that we consume by running code the organization needs to perform its function. Using a direct connection over wires you’ve already paid for, we don’t often have to think about bandwidth, hits on the data store or the amount of compute we use - we just know more is better. In a pay-as-you-go model, however, each of these architecture decisions has a potential cost impact. The amount of data you store, the number of times you access it, and the amount you send back all come with a charge. The offset is that you don’t buy anything at all up-front, so that sunk cost is freed up. And financial professionals know that money now is worth more than money later. Saving that up-front cost allows you to invest it in other things.

It’s not just that you’re using things that now cost money - it’s that the design itself in distributed computing has a cost impact. That can be a really good thing, such as when you dynamically add capacity for paying customers. If you can tie back the cost of a series of clicks to what a user will pay to do so, you can set a profit margin that is easy to track.

Here’s a case in point: Assume you are using a large instance in Windows Azure to compute some data that you retrieve from a SQL Azure database. If you don’t monitor the path of the application, you may not know what you are really using. Since you’re paying by the size of the instance, it’s best to maximize it all the time. Recently I evaluated just this situation, and found that downsizing the instance and adding another one where needed, adding a caching function to the application, moving part of the data into Windows Azure tables not only increased the speed of the application, but reduced the cost and more closely tied the cost to the profit.

The key is this: from the very outset - the design - make sure you include metrics to measure for the cost/performance (sometimes these are the same) for your application. Windows Azure opens up awesome new ways of doing things, so make sure you study distributed systems architecture before you try and force in the application design you have on premises into your new application structure.

Windows Azure Security Review

BuckWoody — Tue, 02 Aug 2011 13:24:50 GMT

Current as of 08/01/2011 - Check the Resources listed below for more up-to-date information on this topic

Background:

Security for any computing platform involves three primary areas:

Principals (users or programmatic access to an asset or other program)
Securables (objects, data or programs that can be accessed)
Channels (methods of access by Principals to Securables)

On-premise systems normally use a central system to control security. In a Windows operating system-based environment, this is often accomplished with Active Directory or other systems that provide sign-on and user identity information. While other networking security paradigms have different terminology, all involve the three areas defined above.

In addition to the names and passwords for a user, Active Directory (like other security mechanisms) store other information about Principals - called Claims. These claims can include any custom fields the provider allows. In many networks, these fields are not used heavily, because applications that eventually need to secure the assets they control are not always deployed on the same platforms everywhere.

In a single environment, security is often quite simple. A Principal is created such as a user or group, and then the Principal is granted access to a Securable such as a a folder, database or other asset. Permissions or Rights (or both) combine to allow a particular Principal to read, write, delete or edit data, or to access or run a particular program.

Figure 1 - On-premise security environment example

The simplicity of this arrangement is due to a single, homogenous boundary. Even if more than one location is used, the Principals and Securables are grouped into a single logical boundary that is managed from one location.

This background serves as the starting point for the Federating Security topic below.

Windows Azure Security Boundaries

Windows Azure is a series of resources - servers, data and service buses, in addition to other features. Developers write code, and the deploy that to the Azure environment.

Figure 2 - Azure Components

The code or data can be deployed to use one or more of the services. In other words, the Web Role in Windows Azure might host a simple website, and no other component need be used.

Figure 3 - Simple Azure Web Role Application - only one feature used

Or, a complex mix of Web, Worker and Data Services, along with a Service Bus, RDBS and even on-site systems can be grouped into a much larger program.

Figure 4 - Complex Windows and SQL Azure Application With Multiple Interactions

For a more basic introduction to Windows and SQL Azure, see this link: http://channel9.msdn.com/Events/TechEd/Europe/2010/COS322

Windows Azure, like any web-based property, has three general layers of security:

Physical Access
Operating Environment (Including the Operating System itself)
Data and Programmatic Security

Each of these layers have additional layers within themselves, and this forms the basis of a secure experience for the end user or program. Some of these layers are the responsibility of Microsoft; others are the responsibility of the architect and developer; others are a joint or shared responsibility of both Microsoft and the client.

Layer One: Physical Access

The first layer of security within a web property such as Windows or SQL Azure is a secure facility. the following data points are important to understand for the worldwide facilities that host Windows and SQL Azure:

Microsoft Global Foundation Services (GFS) is responsible for the physical security of the datacenters located worldwide for Windows and SQL Azure. Information on Microsoft datacenters can be found here: http://www.globalfoundationservices.com/
The address and exact locations facilities are not commonly documented for security reasons.
Microsoft runs it’s own data centers and does not contract this function out.
The GFS controlled facilities hold an ISO/IEC 27001:2005 certification, and are audited to SAS level II.
Standard secure operations protocols are in place, including least-privilege access.

Layer Two: Operating Environment

Windows Azure and SQL Azure do not currently hold certifications. Microsoft does not comment on the security certifications being pursued for Windows or SQL Azure. That being said, the Windows Azure environment is based on a modified Windows 2008 R2 Enterprise environment, developed using the Trustworthy Computing Initiative (TCI).

The system controlling the host machines and their guest environments that ultimately hold the Web and Worker Roles within Windows Azure is called the Fabric - not to be confused with the Application Fabric feature. The Fabric is not accessible by client code - it controls the inner workings of Windows Azure, including Load-balancing, system restarts, maintenance and monitoring.

Within the host machines that house the Web and Worker Roles, special networking constructs broker all conversations between Virtual Machines. Virtual Machines - even ones configured to communicate with each other - move through this network. Direct-machine to machine communication is not allowed, protecting one application from another or one data construct from another.

Figure 5 - Windows Azure Fabric

Windows and SQL Azure support only TCP-based communications. Ports commonly used are:

80 - Default public port used for Web Roles - can be enabled/disabled per configuration
443 - Default secure port used for Web roles - can be enabled/disabled per configuration
9350-9353 - These ports are used by the Windows Azure AppFabric service bus bindings. Refer to http://msdn.microsoft.com/en-us/library/ee732535.aspx for more details
1433 - SQL Azure
3389 - This port is used for RDP access to VM-based roles, only if enabled

Layer Three: Data and Programmatic Security

All internal access through use of keys only. Without the proper key, code or data will not transfer. Storage Accounts have individual keys, so in this manner different security layers may be applied not only programmatically but at the account layer.

Figure 6 - Windows Azure communications between components

Calls to Windows Azure are made using standard SOAP, XML or REST-based protocols. The communications channel can be encrypted between the client and Windows Azure or allow it to remain unencrypted based on security needs.

SQL Azure uses the standard SQL Server Tabular Data Stream (TDS) protocol, but only allows encrypted communications.

Data is unencrypted within Windows Azure Blob or Table Storage - but is only accessible via the key for a storage account. Data can be encrypted client-side and stored in Windows Azure in an encrypted fashion. Microsoft does not inspect internal data for validity or encryption enforcement. The key is that the data is client-side encrypted and decrypted.

Figure 7 - Example data at rest encryption scenario

Alternatively, a hybrid solution can store sensitive data locally and non-sensitive data in Azure Storage. The data can be coalesced at the client level such that the data is never transferred over any channel not owned or controlled by the organization.

Federating Security:

In the case of a single security boundary for Windows Azure, multiple security options are available. Users can be anonymously authorized, such as in the case of a public website for advertisement or informational purposes.

Another option is to create an Internet Information Services (IIS) Internal Security Store. This is not a best-practice (although still possible) approach since the Fabric services within Windows Azure may recycle an instance and the session may sever between a given role and a client. Architecting stateless applications is a preferred approach.

Using Claims-Based Authentication is a better solution. In this approach, the Principal is authenticated through a trusted party, such as Active Directory, OpenID, OpenAuthentication, or LiveID. Many web-properties use these methods, such as Microsoft, Google, Yahoo and Facebook to name a few. After authenticating with one of these services, the client is issued Claims using the WS-Federation (WS-Fed) or Security Assertion Markup Language (SAML) that are passed to Windows Azure. At no time does Windows Azure store, transfer or interrogate the Principal’s security token. Claims can be anything from a group or role membership to location or any other settable attribute. Assets are then secured allowing only the Claim, without regard to the user’s location or access method. In this fashion a single security paradigm covers the Securables, with the Principals being controlled in any number of other mechanisms. This allows single-sign-on and/or federated security access from multiple providers.

The simplest mechanism for building this environment is the Access Control Services (ACS) feature found in the Windows Azure Application Fabric component. It is a federated authorization management service that simplifies user access authorization across organizations and ID providers and performs claims transformation to map identities with access levels.

ACS can:

Create and manage scopes such as URLs
Create and manage claim types
Create and manage signing and encryption keys
Create and manage rules within an application scope
Chain claims rules
Manage permissions on scopes or perform delegation

Figure 8 - Federated Security Example

Full information on the Access Control Service is available at this link: http://social.technet.microsoft.com/wiki/contents/articles/windows-identity-foundation-wif-and-azure-appfabric-access-control-service-acs-survival-guide.aspx?wa=wsignin1.0

Since the Web and Worker Roles within Windows Azure are designed to be stateless, Microsoft created a Certification Store within the Management area to hold Certificates that can be called from within code. An example of using the Certification Store is here: http://blogs.msdn.com/b/jnak/archive/2010/01/29/installing-certificates-in-windows-azure-vms.aspx

Additional Resources:

Official, authoritative security resource list: http://msdn.microsoft.com/en-us/library/ff934690.aspx
Technical Overview of the Security Features in the Windows Azure Platform: http://www.microsoft.com/online/legal/?langid=en-us&docid=11.
Windows Azure Security Overview: http://www.globalfoundationservices.com/security/documents/WindowsAzureSecurityOverview1_0Aug2010.pdf
Windows Azure Privacy: http://www.microsoft.com/online/legal/?langid=en-us&docid=11
Securing Microsoft Cloud Infrastructure: http://www.globalfoundationservices.com/security/documents/SecuringtheMSCloudMay09.pdf.
A list of other security resources is here: http://blogs.msdn.com/b/buckwoody/archive/2010/12/07/windows-azure-learning-plan-security.aspx

Image Attribution: David Pallmann: http://davidpallmann.blogspot.com/2011/07/windows-azure-design-patterns-part-1.html

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Pay in the future should make you think in the present

Windows Azure Security Review