15 Oct 2014

How to migrate a DFS Namespace to Windows Server 2008 Mode

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Hello dear readers,
In this short article I want to show you how to migrate a DFS Namespace that was enabled for Windows 2000 mode.  Suppose you are using a Windows Server 2003 infrastructure and want to migrate it to Windows Server 2008. Besides the OS install you will also need to migrate all the DFS infrastructure to the new Servers. DFS offers the possibility of exporting a namespace to an xml file and then importing it to your new namespace. To migrate our namespace we will use dfsutil command. Open command prompt and type the following:

The namespace will be exported in the specified path
dfsutil root export \\ppscu.com\Documents C:\namespace.xml

We will now remove the namespace by typing the following:
dfsutil root remove \\ppscu.com\Documents

On the new Servers that are running at Windows Server 2008 mode, we will recreate our namespace using the same dfsutil command:

dfsutil root adddom \\ppscu.com\Documents

The config file must now be imported to the new namespace by typing the following:

dfsutil root import merge C:\namespace.xml \\ppscu.com\Documents

Once you migrate all the files and folders to your new servers, you will have a new DFS infrastructure running in Windows Server 2008 mode. The migration process should be easy to follow and implement. That's about it for this short article folks, stay tuned for the following posts from IT training day.
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10 Oct 2014

Deploying DFS namespaces

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Now that we've had our first contact with DFS (Distributed File System) it's time to move further and discover new features of this technology. In this article I will show you how to install and configure DFS on Windows Server 2012 Edition. For this tutorial I will be using two Windows Server 2012 R2 virtual machines that are already deployed within an Active Directory Domain. In the previous article we've talked briefly about about DFS and DFSR, but we still have a long way to go before all aspects of these technologies have been covered.

DFS tutorialWe will start by installing the necessary roles for these two components. Open the Server Manger console on one server, navigate to the Dashboard section and click on Add roles and features button. Expand File and Storage Services and select DFS Namespaces and DFS Replication:
Distributed File System tutorial
Once you've selected these two roles, check the confirmation page and proceed with the installation:

How to configure a DFS namespace
Since DFSR is a multimaster technology, it doesn't matter on which server you'll configure the DFS namespace. Proceed with the installation of both roles on the second machine. Once this operation is completed we'll configure our DFS namespace. Note that we will create a Domain-based namespace since we are using two servers that are part of an Active Directory domain. You can add multiple servers to increase the availability of the DFS namespace in case of failures. 

Open the DFS Management console, navigate to the Namespace section, right click it and select New Namespace. Check out the Actions menu from the right side of the window to view available actions:

DFS namespace Wizard
Since this is the first time the namespace is configured we will need to enter the name of the server hosting the namespace. Once DFSR is configured, the master node concept will not be applicable anymore. 

Distributed File System
In the following section we'll have to configure the name for our namespace. Since we are deploying this namespace within our domain, the newly configured DFS namespace will be available when accessing \\domain_name\namespace_name (in my case \\ppscu.com\Documents):

Distributed File System training
You can configure extra settings in this section by clicking the Edit Settings button. Here you can set the local path of the shared folder and the shared folder permissions. Usually, you will be using custom permissions when deploying a DFS namespace, but for now we will use the default settings:

Domain-based namespace
From the namespace type menu select Domain-based namespace and check Enable Windows Server 2008 mode to support increased features like scalability and access-based enumeration (ABE). Remember that the metadata of Domain-based namespaces are stored within AD DS:

Domain-based namespace tutorial
Review the settings and create the namespace. The newly created namespace will appear in the DFS Management console. We will need to add the second server to our namespace. From the actions menu select Add Namespace Server and add the second machine:

DFS console
On the Namespace Servers tab you can view all machines that are part of this namespace. Delegation tab is used to allow groups and users to administrate the DFS namespace. The Search tab can be used to locate folders or folder targets within the DFS namespace:

DFS tutorialNow let's create a new folder on one of our servers and add it to the DFS namespace. Note that I don't have a dedicated partition to store my shared folders since this is a testing environment. You should always have a separate partition that is different from the OS partition to store shared files and folders. The folder must have sharing activated before adding it to the namespace:
DFS namespace folders
Let's return to the DFS Management console and add this folder as a resource to our namespace. Navigate to the Actions menu and click on New Folder. Set a name for the new folder and browse for it by pressing the Add button:

DFS Referrals
You can configure further settings by right clicking on the namespace name and selecting Properties from the menu. Within the first section we can add a description for the namespace and view the general info. On the Referrals tab we can configure cache duration and set a method for ordering targets outside of the client's site. This option practically tells a DFS client what mechanism to use when trying to access a certain namespace resource. Remember that referrals settings can be configured at the server level or from each folder individually:

DFS Access-based enumeration
On the Advanced section we can optimize polling by selecting one of the two methods available Optimize for consistency and Optimize for scalability. Access-based enumeration (ABE) can also be enabled form this section:

Add Namespace to Display
On the second server the namespace will not be displayed automatically. To achieve this result open the DFS console and press the Add Namespace to Display button:

Now place a file within the folder and try to access it using the correct path. I first disabled the Windows Firewall on both servers just to make sure that there will be no network issues when accessing DFS shared folders. I've then typed \\ppscu.com\Documents\DanP from the second machine to verify if the namespace has been configured correctly:
Even though we've added two servers to host our namespace, replication hasn't been configured yet so resources will be accessible only on the server hosting the specified folder. If you verify the shared folder on both servers using DFS Management console you will see that the second machine has listed the folder's name but does not host its content.
In the following article I will show you how to configure DFS Replication for our newly created namespace and we will see how files and folders are replicated between DFS servers. Please don't hesitate to post a comment if there are things left unclear. Don't forget to enjoy your day and stay tuned for the following articles from IT training day.
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6 Oct 2014

Introduction to DFS

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Distributed File System (DFS) is a technology created by Microsoft to allow data consistency across large enterprises. DFS allows you to group shared folders from multiple servers into one or more namespaces. A namespace is a hierarchy of folders grouped together to create on large data tree. There are two main technologies that we must talk about on this topic: DFS and DFSR:

DFS is responsible for managing all the namespaces that are part of an organization. Note that DFS allows shared folders to be accessible across WAN links. DFS operation is done transparent to the user, which means that folders will appear just if they are stored in the same location. One unique and centralized namespace can be easily maintained by Sysadmins rather than using a distributed folders across multiple servers. DFS manages only the namespace and the hierarchy of folders and does not replicate files and folders between servers. Note that with Windows Server 2008 Standard Edition you can create only one namespace. Multiple namespaces are supported by Enterprise and Datacenter Editions. A namespace can be accessed using its UNC (Universal Naming Convention) path. Users will need access rights to be able to access the namespace. There are two types of DFS namespaces that you can create:

Stand-Alone Namespace - namespace that is not domain-based, can be hosted on a server that contains at least one NTFS volume. It also offers support for ABE (access-based enumeration) if it's hosted on a Windows Server 2008 or newer Editions. ABE allows users to view only the folders on which they have permissions. This feature is not enabled and can be configured using the dfsutil command (dfsutil property abde enable \\namespace_name). Stand-Alone namespaces can be hosted on a failover cluster for redundancy.

Domain-Based Namespace - namespace hosted on a DC or a member server that is part of a domain. Servers must also have a NTFS partition to host the DFS namespace. One important aspect of domain-based namespace is that the metadata is stored in AD DS and can be easily accessed by any DFS server. Note that this type of namespace cannot be stored within a failover cluster but, availability can be increased by adding more DFS members.
Introduction to DFS

A DFS namespace can be easily maintained using the DFS Management Console. Cache referrals can be configured to set the amount of time clients will store referrals for a namespace. We can also set the order on how clients will try to access folders that are in a different site. There are three methods available: Lowest Cost, Exclude Targets Outside Of The Clients Site and Random Order.
When a user will try to access shared folders that are part of the namespace, he/she will receive an ordered list from the Domain Controller. The list will contain the servers that host that specific resource. Based on the method configured on the namespace, a server will have a higher or lower priority when files and folders are requested. You can overwrite the referral ordering form the namespace Properties in the DFS Management Console
Namespace modes can be configured when creating the namespace, we will talk about available modes later in this article.
Depending on your network's size and needs, you can optimize the namespace polling for domain-based namespaces. You can Optimize pooling for Consistency or Optimize For Scalability.

We haven't talked about the DFS modes that you can use within your infrastructure. DFS supports two domain-based namespaces:
Windows Server 2000 mode - available with Windows Server 2003 R2 and 2008 Editions.
Windows Server 2008 mode - available with newer Windows Server Editions. You can enable access-based enumeration. This mode also provides increased server stability because you can now have a DFS namespace with more than 5000 folders. You can enable Windows Server 2008 mode if all your DFS servers are running this server edition and if the functional level of the domain is at Windows Server 2008. You should use this DFS mode whenever possible.

DFSR (Distributed File System Replication) manages the replication of shared folders between different parts of the network. This is a newer technology introduced with Windows Server 2008 to replace FRS (File Replication Service) that was used in older Windows Server Editions. DFSR is also used to replicate the SYSVOL folder in a AD DS infrastructure. You can configure replication to make sure that multiple servers host the same data within your infrastructure. Not only you provide a reliable way to store your data but also allows users to access files and folders which would normally be accessible remotely. Large enterprises will normally host a DFSR server in all of their offices ensuring that users can access data fast and secure. A user will always try to connect to shared folders in the same AD DS site and will not try to access it through the WAN link. DFSR is a multimaster technology which means that any changes within the shared folders will be replicated fast to all servers part of the replication group. DFSR uses a compression algorithm named RDC (remote differential compression) which is responsible for detecting changes that occur in the files and folders hosted on the DFS namespace. Replication topology must be specified when creating replication groups. You can choose either Hub and Spoke, Full mesh or No topology.

This introduction article should provide you some basic info regarding DFS and DFSR, in the following posts we will continue discovering this amazing technology and we will later see how to install and configure them. That's about it folks, hope you've enjoyed it. Wish you all the best!
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29 Sep 2014

Windows Server VPN Protocols

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Windows Server VPN Protocols
In the past article we've discussed a bit about VPN authentication protocols used with Windows Server Editions. We cannot talk about VPN authentication protocols without talking about the different VPN protocols that can be used with Windows Server 2008 and 2012. Based on the necessities of your company, you can opt for one of the four VPN protocols, as follows:

PPTP (Point-to-Point Tunneling Protocol) - one of the first VPN protocols that are still used today. It uses MPPE (Microsoft Point-to-Point Encryption) protocol to encrypt data sent by VPN clients. Even if this protocol provides features for data confidentiality it does not support data origin authentication nor data integrity so it's susceptible to exploits. PPTP connections can be authenticated using either MS-CHAP, MS-CHAPv2, PEAP or EAP. PPTP can be used with EAP-TLS but for that you will need a local CA (Certification Authority) deployed with a certificate installed on the VPN Server. Note that unlike other protocols, with PPTP EAP-TLS you don't need to install the certificate on the VPN clients. PPTP is mostly used with non-Microsoft products because it offers compatibility with all Operating Systems. You should opt for a newer VPN protocol whenever possible because others offer increased security.

L2TP/IPSec (Layer 2 Tunneling Protocol with Internet Protocol Security) - tunneling protocol that does not provide encryption or confidentiality alone. With Microsoft VPN Server, it's used with IPSec which deals with data encryption before it's sent on the tunnel. There are two levels of authentication that occurs within a L2TP/IPSec communication:
Computer authentication - made using digital certificates issued by a Certificate Authority trusted by both the Server and the Client.
Client authentication - this authentication mechanism is made using one of the PPP authentication Protocols discussed in the previous article.
This protocol offers data origin authentication, data confidentiality, data integrity and replay protection.

SSTP (Secure Socket Tunneling Protocol) - an authentication protocol which encapsulates PPP or L2TP traffic through an SSL 3.0 channel. The SSL traffic is passed using HTTPS (Hypertext Transfer Protocol Secure) which means that the traffic is passed by almost all routers or firewalls because 443 port is usually opened in the public Internet. The use of SSL provides transport-level security with key-negotiation, integrity checking and encryption. To successful deploy SSTP within your organization, you will need to take into consideration several factors. SSTP is supported only by Windows Server 2008 or newer Editions this is why it cannot be used with Windows Server 2003. You will also need a trusted CA to issue certificates for your Server and the Server must first install the certificate before enabling Routing and Remote Access. The client will then be able to connect using the VPN Server hostname that must be the same to the subject name specified in the SSL Certificate. Note that with SSTP you cannot create site-to-site tunnels and you cannot tunnel SSTP traffic on proxies which require authentication.

IKEv2 (Internet Key Exchange) a VPN tunneling protocol supported by Routing and Remote Access Service (RRAS). The protocol is used to configure a SA (Security Association) in the IPSec communication. Read more about Security Associations here. You will need a local CA issuing certificates with Enhanced Key Usage (EKU) options. You will then need to generate the authentication certificate and import it to the VPN Server store. IKEv2 offers support for VPN Reconnect (also known as Agile VPN) which is a technology that tolerates network interruptions. The VPN connection is re-established without the user intervention once the Internet connection is established again. Read more about IKE on this article from Wikipedia.

This was a short introduction to VPN Protcols that can be used on Windows Server Editions. The article should provide an overview of these protocols so you will better understand VPN technologies. For any questions on this topic, use my comments section. Wish you a wonderful day!
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18 Sep 2014

Windows Server VPN Authentication Protocols

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VPN authentication Methods  VPN or Virtual Private Network is a technology that offers a secure way to establish communication channels between devices by using the public Internet. As a concept, VPN offers three main features: encapsulation, authentication and encryption. These features play an important role because they ensure data is not compromised by a potential attacker. A common VPN scenario would be something like in the following example: a client would try to connect to a VPN server or a dedicated VPN equipment to establish a secure tunnel with the destination network. Before the client can access network resources, the VPN server must first authenticate the connection. There are several authentication protocols supported by Windows Server 2012 or 2008. The Server will always try to use the strongest authentication method and then proceed with the others if the process is not successful. In this article I will try to create a summary of the authentication protocols used with Windows Server Editions and we'll see what are the differences between them. 

   EAP-TLS (Extensible Authentication Protocol - Transport Layer Security) - One of the most secured authentication protocols used today that takes advantage of TLS (Transport Layer Security). Can be implemented on a Windwos Server 2008 or 2012 that is part of an Active Directory Infrastructure. EAP-TLS can be used by VPN clients authenticating using either smart-cards or certificates. This technology offers a secure authentication protocol because each client must store a valid X.509 certificate. This means that besides the client's password, an attacker must get access to the private key of the certificate in order to infiltrate the network. If your company decides to store certificates within smart-cards, you increase network security even further because smart-cards can be compromised only by physical theft. Within the corporate network you would need to deploy a Certificate Authority to issue digitally signed certificates for VPN clients.

   MS-CHAP v2 (Microsoft Challenge Handshake Authentication Protocol version 2) - this authentication protocol is enabled by default on Windows Server Editions. MS-CHAP v2 offers a two-way authentication mechanism which verifies the identity of the VPN server and the VPN client. Both parties authenticate with each other by using two different  cryptographic keys. MS-CHAP v2 uses a unique session identifier and user credentials to generate encryption keys unlike EAP-TLS which takes advantage of digital certificates.

   CHAP (Challenge Handshake Authentication Protocol) - is an older authentication protocol that uses MD5 hash algorithms to send the authentication requests. The VPN Server sends a challenge to the VPN client which in turn responds with an MD5 hash result that is composed of the challenge and the user's password. The VPN Server calculates the user's hash locally and compares the result with the hash received from the VPN client. If these two hashes match, then the user is granted network access. You should use this authentication mechanism if EAP-TLS is not supported within your network.

   EAP-MD5 CHAP (EAP-Message Digest 5 Challenge Handshake Authentication Protocol) - a version of CHAP that takes advantage of EAP framework. Offers encryption of authentication data using MD5 hasing. It has a lot of weakness and it's known as being vulnerable to dictionary attacks. It offers authentication from client to server but not the other way around, this is why  EAP-MD5 CHAP is vulnerable to man-in-the-middle attacks. Was used with older Windows Server Editions and should not be used anymore.

   SPAP and PAP - two simple authentication protocols that are not widely used since they use basic authentication mechanisms and are susceptible to external attacks. PAP uses plain-text passwords that are sent to the server for authentication. With SPAP the password is encrypted before it's sent to the server. SPAP uses a two-way encryption algorithm, but it's not a secured authentication protocol. You should not use these two protocols for VPN authentication

These are the VPN authentication protocols that can be used with Windows Server Editions. Whenever possible choose the strongest algorithm to ensure data confidentiality against foreign attacks. Hope you'll find this article interesting and use it to enhance your Windows Server VPN knowledge. Wish you all the best and stay tuned for the following articles.
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