Always On VPN Updates to Improve Connection Reliability

Always On VPN Updates to Improve Connection ReliabilityA longstanding issue with Windows 10 Always On VPN is that of VPN tunnel connectivity reliability and device tunnel/user tunnel interoperability. Many administrators have reported that Always On VPN connections fail to establish automatically at times, that only one tunnel comes up at a time (user tunnel or device tunnel, but not both), or that VPN tunnels fail to establish when coming out of sleep or hibernate modes. Have a look at the comments on this post and you’ll get a good understanding of the issues with Always On VPN.

Recent Updates

The good news is that most of these issues have been resolved with recent updates to Windows 10 1803 and 1809. Specifically, the February 19, 2019 update for Windows 10 1803 (KB4487029) and the March 1, 2019 update for Windows 10 1809 (KB4482887) include fixes to address these known issues. Administrators are encouraged to deploy Windows 10 1803 with the latest updates applied when implementing Always On VPN. Windows 10 1809 with the latest updates applied is preferred though.

Persistent Issues

Although initial reports are favorable for these updates and based on my experience the effectiveness and reliability of Windows 10 Always On VPN is greatly improved, there have still been some reports of intermittent VPN tunnel establishment failures.

Possible Causes

During my testing, after applying the updates referenced earlier both device tunnel and user tunnel connections are established much more consistently than before the updates were applied. I did encounter some issues, however. Specifically, when coming out of sleep or hibernate, VPN connections would fail to establish. Occasionally VPN connections would fail after a complete restart.

NCSI

After further investigation it was determined that the connectivity failure was caused by the Network Connectivity Status Indicator (NCSI) probe failing, causing Windows to report “No Internet access”.

Always On VPN Updates to Improve Connection Reliability

Cisco Umbrella Roaming Client

In this instance the NCSI probe failure was caused by the Cisco Umbrella Roaming Client installed and running on the device. The Umbrella Roaming Client is security software that provides client protection by monitoring and filtering DNS queries. It operates by configuring a DNS listener on the loopback address. NCSI probes are known to fail when the DNS server is running on a different interface than is being tested.

Resolution

Microsoft released a fix for this issue in Windows 10 1709. The fix involves changing a group policy setting to disable interface binding when perform DNS lookups by the NCSI. You can enable this setting via Active Directory group policy by navigating to Computer Configuration > Administrative Templates > Network > Network Connectivity Status Indicator > Specify global DNS. Select Enabled and check the option to Use global DNS, as shown here.

Always On VPN Updates to Improve Connection Reliability

For testing purposes this setting can be enabled individual using the following PowerShell command.

New-ItemProperty -Path “HKLM:\SOFTWARE\Policies\Microsoft\Windows\NetworkConnectivityStatusIndicator\” -Name UseGlobalDNS -PropertyType DWORD -Value 1 -Force

Third-Party Software

As Always On VPN connectivity can be affected by NCSI, any third-party firewall or antivirus/antimalware solution could potentially introduce VPN connection instability. Observe NCSI operation closely when troubleshooting unreliable connections with Always On VPN.

Additional Information

Windows 10 1803 Update KB4487029

Windows 10 1809 Update KB4482887

Cisco Umbrella Roaming Client Limited Network Connectivity Warning

Network Connectivity Status Indicator (NCSI) Operation Explained

Cloudflare Public DNS Resolver Now Available

Cloudflare Public DNS Resolver Now AvailableCloudflare has become a nearly ubiquitous cloud service provider in recent years, fronting many of the busiest web sites on the Internet. They provide tremendous value both in terms of security and performance for their customers. They have a wide array of solutions designed to provide better security, including optimized SSL/TLS configuration and Web Application Firewall (WAF) capabilities. Their DDoS mitigation service is second to none, and their robust Content Delivery Network (CDN) ensures optimal loading of content for web sites anywhere in the world.

Public DNS Resolver

Recently Cloudflare announced their first consumer service, a public DNS resolver that is free for general use. It offers exceptional performance and supports many of the latest DNS security and privacy enhancements such as DNS-over-TLS. Cloudflare has also pledged not to write DNS queries to disk at all and not to store them for more than 24 hours to further ensure privacy for their customers.

Cloudflare Public DNS Resolver Now Available

DNS Security Controls

What Cloudflare DNS is lacking today is granular security enforcement to provide additional protection for client computers outside the firewall. For example, public DNS resolvers from OpenDNS and Quad9 have built-in security features that use threat intelligence to identify and block DNS name resolution requests for domains that are known to be malicious or unsafe. OpenDNS has the added benefit of providing more granularity for setting policy, allowing administrators to select different filtering levels and optionally to create custom policies to allow or block individually selected categories. With OpenDNS, security administrators can also manage domains individually by manually assigning allow or block to specific, individual domains as necessary.

Recommended Use Cases

Cloudflare DNS clearly offers the best performance of all public DNS resolvers today, which makes it a good candidate for servers that rely heavily on DNS for operation. Mail servers come to mind immediately, but any system that performs many forward and/or reverse DNS lookups would benefit from using Cloudflare DNS. Cloudflare DNS can also be used by client machines where better performance and enhanced privacy are desired.

Quad9 DNS is a good choice for client computers where additional security is required. OpenDNS is the best choice where the highest level of security is required, and where granular control of security and web filtering policies is necessary.

Additional Information

Cloudflare DNS
Quad9 DNS
OpenDNS
Dnsperf.com

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