Troubleshooting Always On VPN Error 691 and 812 – Part 3

Troubleshooting Always On VPN Error 691 and 812 – Part 2When implementing Windows 10 Always On VPN, administrators may encounter errors 691 or 812 when establishing a VPN connection. There are several different configuration issues that will result in these errors. For example they may occur when TLS 1.0 has been disabled on the RRAS server when installed on servers prior to Windows Server 2016. It can also happen if a user’s Active Directory account is configured to deny dial-in access and the NPS server is not configured to ignore user account dial-in properties. Another scenario that can result in 691/812 errors is when the Active Directory security groups are configured as conditions on the Network Policy Server (NPS) Network Policy. See below for more details.

SSTP and Error 691

When attempting to establish an Always On VPN connection using the Secure Socket Tunneling Protocol (SSTP), administrators may encounter the following error message.

“The remote connection was denied because the user name and password combination you provided is not recognized, or the selected authentication protocol is not permitted on the remote access server.”

Troubleshooting Always On VPN Error 691 and 812 – Part 2

In addition, an error 691 with event ID 20227 from the RasClient source can be found in the Application event log on the client.

“The user <domain\user> dialed a connection named which has failed. The error code returned on failure is 691.”

Troubleshooting Always On VPN Error 691 and 812 – Part 2

IKEv2 and Error 812

When attempting to establish an Always On VPN connection using Internet Key Exchange version 2 (IKEv2), administrators may encounter the following error message.

“The connection as prevented because of a policy configured on your RAS/VPN server. Specifically, the authentication method used by the server to verify your username and password may not match the authentication method configured in your connection profile. Please contact the Administrator of the RAS server and notify them of this error.”

Troubleshooting Always On VPN Error 691 and 812 – Part 2

In addition, an error 812 with event ID 20227 from the RasClient source can be found in the Application event log on the client.

Troubleshooting Always On VPN Error 691 and 812 – Part 2

NPS Event Log

On the NPS server the administrator will find an entry in the application event log with event ID 6273 from the Microsoft Windows security auditing source and the Network Policy Server task category indicating the network policy server denied access to the user. Looking closely at this event log message shows Reason Code 48 and the following reason.

“The connection request did not match any configured network policy.”

Troubleshooting Always On VPN Error 691 and 812 – Part 2Group Membership

As stated earlier, another scenario in which administrators will encounter errors 691 and/or 812 is when the Network Policy on the NPS server is configured incorrectly. Specifically, and administrator may wish to grant access to more than one group but intend for access to be granted to users who are a member of any of them. Conversely, they may wish to require access in all specified groups to gain access to the VPN. Configuring each of these conditions is subtly different, however.

Open the NPS management console on the NPS server and follow the steps below to configure user group conditions correctly for the following scenarios.

Any Group

1. Right-click the Always On VPN network policy and choose Properties.
2. Click on the Conditions tab.
3. Click the Add button.
4. Click User Groups.
5. Click Add.
6. Click Add Groups.
7. Enter the name of the group you want to grant access to.
8. Click Ok.
9. Repeat the steps 6-8 above to specify additional groups.

Troubleshooting Always On VPN Errors 691 and 812

All Groups

1. Right-click the Always On VPN network policy and choose Properties.
2. Click on the Conditions tab.
3. Click the Add button.
4. Click User Groups.
5. Click Add.
6. Click Add Groups.
7. Enter the name of the group you want to grant access to.
8. Click Ok.
9. Repeat steps 3-8 above to specify additional groups (you must go back to the Add button on step 3!).

Troubleshooting Always On VPN Errors 691 and 812

Additional Information

Troubleshooting Always On VPN Error 691 and 812 – Part 1

Troubleshooting Always On VPN Error 691 and 812 – Part 2

Always On VPN IKEv2 Load Balancing and NAT

Always On VPN IKEv2 Load Balancing and NATOver the last few weeks, I’ve worked with numerous organizations and individuals troubleshooting connectivity and performance issues associated with Windows 10 Always On VPN, and specifically connections using the Internet Key Exchange version 2 (IKEv2) VPN protocol. An issue that appears with some regularity is when Windows 10 clients fail to connect with error 809. In this scenario, the server will accept connections without issue for a period of time and then suddenly stop accepting requests. When this happens, existing connections continue to work without issue in most cases. Frequently this occurs with Windows Server Routing and Remote Access Service (RRAS) servers configured in a clustered array behind an External Load Balancer (ELB).

Network Address Translation

It is not uncommon to use Network Address Translation (NAT) when configuring Always On VPN. In fact, for most deployments the public IP address for the VPN server resides not on the VPN server, but on an edge firewall or load balancer connected directly to the Internet. The firewall/load balancer is then configured to translate the destination address to the private IP address assigned to the VPN server in the perimeter/DMZ or the internal network. This is known a Destination NAT (DNAT). Using this configuration, the client’s original source IP address is left intact. This configuration presents no issues for Always On VPN.

Source Address Translation

When troubleshooting these issues, the common denominator seems to be the use of Full NAT, which includes translating the source address in addition to the destination. This results in VPN client requests arriving at the VPN server as appearing not to come from the client’s original IP address, but the IP address of the network device (firewall or load balancer) that is translating the request. Full NAT may be explicitly configured by an administrator, or in the case of many load balancers, configured implicitly because the load balancer is effectively proxying the connection.

Known Issues

IKEv2 VPN connections use IPsec for encryption, and by default, Windows limits the number of IPsec Security Associations (SAs) coming from a single IP address. When a NAT device is performing destination/full NAT, the VPN server sees all inbound IKEv2 VPN requests as coming from the same IP address. When this happens, clients connecting using IKEv2 may fail to connect, most commonly when the server is under moderate to heavy load.

Resolution

The way to resolve this issue is to ensure that any load balancers or NAT devices are not translating the source address but are performing destination NAT only. The following is configuration guidance for F5, Citrix ADC (formerly NetScaler), and Kemp load balancers.

F5

On the F5 BIG-IP load balancer, navigate to the Properties > Configuration page of the IKEv2 UDP 500 virtual server and choose None from the Source Address Translation drop-down list. Repeat this step for the IKEv2 UDP 4500 virtual server.

Always On VPN IKEv2 Load Balancing and NAT

Citrix ADC

On the Citrix ADC load balancer, navigate to System > Settings > Configure Modes and check the option to Use Subnet IP.

Always On VPN IKEv2 Load Balancing and NAT

Next, navigate to Traffic Management > Load Balancing > Service Groups and select the IKEv2 UDP 500 service group. In the Settings section click edit and select Use Client IP. Repeat these steps for the IKEv2 UDP 4500 service group.

Always On VPN IKEv2 Load Balancing and NAT

Kemp

On the Kemp LoadMaster load balancer, navigate to Virtual Services > View/Modify Services and click Modify on the IKEv2 UDP 500 virtual service. Expand Standard Options and select Transparency. Repeat this step for the IKEv2 UDP 4500 virtual service.

Always On VPN IKEv2 Load Balancing and NAT

Caveat

Making the changes above may introduce routing issues in your environment. When configuring these settings, it may be necessary to configure the VPN server’s default gateway to use the load balancer to ensure proper routing. If this is not possible, consider implementing the workaround below.

Workaround

To fully resolve this issue the above changes should be made to ensure the VPN server can see the client’s original source IP address. If that’s not possible for any reason, the following registry key can be configured to increase the number of established SAs from a single IP address. Be advised this is only a partial workaround and may not fully eliminate failed IKEv2 connections. There are other settings in Windows that can prevent multiple connections from a single IP address which are not adjustable at this time.

To implement this registry change, open an elevated PowerShell command window on the RRAS server and run the following commands. Repeat these commands on all RRAS servers in the organization.

New-ItemProperty -Path ‘HKLM:SYSTEM\CurrentControlSet\Services\IKEEXT\Parameters\’ -Name IkeNumEstablishedForInitialQuery -PropertyType DWORD -Value 50000 -Force

Restart-Service IKEEXT -Force -PassThru

Additional Information

IPsec Traffic May Be Blocked When A Computer is Behind a Load Balancer

Windows 10 Always On VPN IKEv2 Load Balancing with Citrix NetScaler ADC

Windows 10 Always On VPN IKEv2 Load Balancing with F5 BIG-IP

Windows 10 Always On VPN IKEv2 Load Balancing with Kemp LoadMaster

Troubleshooting Always On VPN Error 691 and 812 – Part 2

Troubleshooting Always On VPN Error 691 and 812 – Part 2A while back I wrote about troubleshooting and resolving Windows 10 Always On VPN errors 691 and 812. There are numerous issues that can result in these errors, and in that post I pointed out they can be caused by disabling TLS 1.0 on Windows Servers prior to Windows Server 2016. However, administrators may encounter a another scenario in which they receive errors 691 or 812 which is related to Active Directory user account configuration.

SSTP and Error 691

When attempting to establish an Always On VPN connection using the Secure Socket Tunneling Protocol (SSTP), administrators may encounter the following error message.

“The remote connection was denied because the user name and password combination you provided is not recognized, or the selected authentication protocol is not permitted on the remote access server.”

Troubleshooting Always On VPN Error 691 and 812 – Part 2

In addition, an error 691 with event ID 20227 from the RasClient source can be found in the Application event log on the client.

“The user <domain\user> dialed a connection named which has failed. The error code returned on failure is 691.”

Troubleshooting Always On VPN Error 691 and 812 – Part 2

IKEv2 and Error 812

When attempting to establish an Always On VPN connection using Internet Key Exchange version 2 (IKEv2), administrators may encounter the following error message.

“The connection as prevented because of a policy configured on your RAS/VPN server. Specifically, the authentication method used by the server to verify your username and password may not match the authentication method configured in your connection profile. Please contact the Administrator of the RAS server and notify them of this error.”

Troubleshooting Always On VPN Error 691 and 812 – Part 2

In addition, an error 812 with event ID 20227 from the RasClient source can be found in the Application event log on the client.

Troubleshooting Always On VPN Error 691 and 812 – Part 2

NPS Event Log

On the NPS server the administrator will find an entry in the application event log with event ID 6273 from the Microsoft Windows security auditing source and the Network Policy Server task category indicating the network policy server denied access to the user. Looking closely at this event log message shows Reason Code 65 and the following reason.

“The Network Access Permission setting in the dial-in properties of the user account in Active Directory is set to Deny access to the user. To change the Network Access permission setting to either Allow access or Control access through NPS Network Policy, obtain the properties of the user account in Active Directory Users and Computers, click the Dial-in tab, and change Network Access Permission.”

Troubleshooting Always On VPN Error 691 and 812 – Part 2

Resolution

There are two options available to address this issue. The user account in Active Directory can be configured to grant access or allow access to be controlled via NPS network policy, or the NPS network policy can be configured to ignore user account dial-in properties.

User Account

Follow the steps below to change Network Access Permission on an individual user’s Active Directory account.

  1. Open the Active Directory User and Computers (ADUC) management console (dsa.msc) and double-click the user’s account.
  2. Select the Dial-in tab.
  3. In the Network Access Permission section select the option to Allow access or Control access through NPS Network Policy.

Troubleshooting Always On VPN Error 691 and 812 – Part 2

Note: If you do not see the dial-in tab, open the ADUC console on a domain controller. The dial-in tab is not displayed when using the Remote Server Administration Tools (RSAT) for Windows clients.

Network Policy

Follow the steps below to configure NPS network policy to ignore user account dial-in properties.

  1. Open the NPS management console (nps.msc) and double-click the Always On VPN network policy.
  2. In the Access Permission section select Ignore user account dial-in properties.
  3. Click Ok to save the changes.

Troubleshooting Always On VPN Error 691 and 812 – Part 2

Additional Information

Windows 10 Always On VPN Troubleshooting Error 691 and 812