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DirectAccess is a new feature of Windows 7 and Windows Server 2008 R2. It has the same purpose as VPN, i.e., it allows users to connect securely to the corporate network through the Internet. The main difference is that the connection is established in the background without requiring user interaction. This article is mostly a summary of Microsoft’s white paper Technical Overview of DirectAccess in Windows 7 and Windows Server 2008 R2. I also installed DirectAccess on Windows Server 2008 R2, but since there is no technical documentation yet, I had to postpone more detailed tests until Microsoft provides more information. In my next post I will share some practical experiences. DirectAccess-Internet-traffic-routing

Requirements

  • DirectAccess server must run on Windows Server 2008 R2
  • DirectAccess client must run on Windows 7
  • DirectAccess Server requires two network cards
  • Active Directory
  • IPv6
  • PKI (Public Key Infrastructure)

Advantages of Direct Access

  • User doesn’t have to establish the connection
  • User doesn’t have to reconnect if the Internet connection breaks
  • Group Policy settings get active before user logs on
  • Users can log on to Active Directory, just like in the intranet
  • Works together with NAP (Network Access Protection) and NAC (Network Access Control) solutions
  • Communication to the corporate network is encrypted with IPsec

Two IPsec tunnels (and authentication methods)

  • Only the machine certificate is used for authentication: The remote computer can only connect to the corporate DNS server, Group Policy, and to Active Directory in order to be able to log on
  • The machine certificate and user credentials are used for authentication: Only then will DirectAccess grant access to other internal resources

Two connection methods

    DirectAccess-Selected-Server-Access

  • Selected Server Access: IPsec connection through DirectAccess server to each application server; application servers have to run Windows Server 2008 R2 or Windows Server 2008 and must support IPv6 and IPsec DirectAccess-Full-Enterprise-Network-Access
  • Full Enterprise Network Access: IPsec connection to an IPsec gateway (can be the DirectAccess server); IPsec gateway forwards traffic to IPv4 application servers

Connection through the Internet

  • If a native IPv6 network isn’t available, the client has to establish an IPv6 over IPv4 tunnel
  • Tunnel protocols supported: Teredo, 6to4 or Intra-Site Automatic Tunnel Addressing Protocol (ISATAP), IP-HTTPS (firewall friendly)
  • By default, Internet traffic is not routed through DirectAccess server
  • Administrators can configure Windows Firewall to route traffic for specific applications or subnets through the DirectAccess server

Also check out my article about the experiences I made with DirectAccess.