3 Important Advantages of Always On VPN over DirectAccess

3 Important Advantages of Always On VPN over DirectAccess Windows 10 Always On VPN hands-on training classes now forming. Details here.

Windows 10 Always On VPN provides seamless and transparent, always on remote network access similar to DirectAccess. The mechanics of how it is delivered and managed are fundamentally different, as I discussed here. Some of these changes will no doubt present challenges to our way of thinking, especially in the terms of client provisioning. However, Always On VPN brings along with it some important and significant advantages too.

No More NLS

A Network Location Server (NLS) is used for inside/outside detection by DirectAccess clients. By design, the NLS is reachable by DirectAccess machines only when they are on the internal network. NLS availability is crucial. If the NLS is offline or unreachable for any reason at all, DirectAccess clients on the internal network will mistakenly believe they are outside the network. In this scenario, the client will attempt to establish a DirectAccess connection even though it is inside. This often fails, leaving the DirectAccess client in a state where it cannot connect to any internal resources by name until the NLS is brought back online.

Always On VPN eliminates the frailty of NLS by using the DNS connection suffix for trusted network detection. When a network connection is established, an Always On VPN connection will not be established if the DNS connection suffix matches what the administrator has defined as the internal trusted network.

Full Support for IPv4

DirectAccess uses IPv6 exclusively for communication between remote DirectAccess clients and the DirectAccess server. IPv6 translation technologies allow for communication to internal IPv4 hosts. While this works for the vast majority of scenarios, there are still many challenges with applications that do not support IPv6.

Always On VPN supports both IPv4 and IPv6, so application incompatibility issues will be a thing of the past! With full support for IPv4, the need for IPv6 transition and translation technologies is eliminated. This reduces protocol overhead and improves network performance.

Infrastructure Independent

3 Important Advantages of Always On VPN over DirectAccess Windows servers are required to implement DirectAccess. Always On VPN can be implemented using Windows servers as well, but it isn’t a hard requirement. Always On VPN is implemented entirely on the Windows 10 client, which means any third-party VPN device can be used on the back end, including Cisco, Checkpoint, Juniper, Palo Alto, Fortinet, SonicWALL, F5, strongSwan, and others! This provides tremendous deployment flexibility, making it possible to mix and match backend infrastructure if required. For example, a Windows RRAS VPN server with Palo Alto and SonicWALL firewalls could all be implemented at the same time (using the Windows built-in VPN client). Importantly, making changes to VPN infrastructure is much less impactful and disruptive to clients in the field. VPN devices can be upgraded, replaced, and moved internally without requiring corresponding policy changes on the client.

Additional Information

Always On VPN and the Future of Microsoft DirectAccess 

5 Things DirectAccess Administrators Should Know about Always On VPN 

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Outlook Offline over DirectAccess on Windows 10

Outlook Offline over DirectAccess on Windows 10You may encounter a scenario in which Outlook on Windows 10 reports that it is working offline while connected remotely via DirectAccess. The Network Connectivity Status Indicator (NCSI) shows DirectAccess is in a connected state and all other internal resources are accessible.

Outlook Offline over DirectAccess on Windows 10

This is caused by the default settings of the IP-HTTPS tunnel interface on the DirectAccess server not advertising a default route for connected DirectAccess clients. To resolve this issue, enable default route advertising for IP-HTTPS on each DirectAccess server in the enterprise by running the following PowerShell command.

Get-NetIPInterface | Where-Object {$_.InterfaceAlias -eq “IPHTTPSInterface”} | Set-NetIPInterface -AdvertiseDefaultRoute Enabled -PassThru

Outlook Offline over DirectAccess on Windows 10

In the past I’ve heard reports of this setting being overwritten after group policy refresh. Recent testing on Windows Server 2016 does not show this behavior, however. Please report any results you may have in the comments below. Thanks!

SSL Certificate Considerations for DirectAccess IP-HTTPS

SSL Certificate Considerations for DirectAccess IP-HTTPSDirectAccess uses IPv6 exclusively for communication between the client and server. IPv6 transition technologies are used to support DirectAccess communication over the IPv4 public Internet. One of those IPv6 transition technologies, IP-HTTPS, uses HTTP for encapsulation and SSL/TLS for authentication of the DirectAccess server.

SSL Certificates

When configuring DirectAccess, an SSL certificate must be provided for IP-HTTPS. There are three different types of SSL certificates that can be used.

Public SSL Certificate – Using an SSL certificate signed by a public certification authority (CA) is the recommended best practice for configuring DirectAccess IP-HTTPS. This provides the highest level of assurance for DirectAccess clients connecting via IP-HTTPS.

Private SSL Certificate – Using an SSL certificate issued by the organization’s internal CA is an acceptable alternative to using a public SSL certificate in most cases. This can reduce the cost associated with obtaining the certificate, especially for multisite deployments.

Self-Signed Certificate – Using a self-signed certificate is not recommended and should be avoided in most deployment scenarios. A self-signed certificate provides no real assurance for DirectAccess clients. Crucially, using a self-signed certificate will disable support for null SSL and TLS cipher suites. This reduces the overall scalability and performance of the remote access solution.

SSL Certificate Considerations for DirectAccess IP-HTTPS

Figure 1. Null cipher suites not supported when using a self-signed SSL certificate for IP-HTTPS.

Certificate Requirements

The SSL certificate must include the Server Authentication (1.3.6.1.5.5.7.3.1) Enhanced Key Usage (EKU) Object Identifier (OID). It should use an RSA key of 2048 bits and be signed with SHA256. Using stronger keys provides no additional protection and should not be used. In addition, SSL certificates using ECDSA keys is not recommended, as they do not support null cipher suites.

Summary

In most cases, using a public SSL certificate is ideal. However, issuing a certificate from a private CA is also acceptable. Using self-signed certificates can be used for non-production testing and in very small production deployments, but should generally be avoided.

Additional Resources

DirectAccess IP-HTTPS SSL and TLS Insecure Cipher Suites

DirectAccess and Multi-SAN SSL Certificates for IP-HTTPS