In this blog article we are going to discuss about How to setup L2TP VPN over IPSec on Windows Server 2019 using Routing and Remote Access Service server role. A VPN is short form of virtual private network, which gives us a privacy, anonymity and security over public internet. A VPN service masks our ISP IP so your online actions are virtually untraceable. A VPN can also be used to connect computers to isolated remote computer networks that is usually inaccessible, by using the Internet or another intermediate network.

Microsoft servers provided with RRAS server roles for implementing such remote access services. The full form of RRAS is Routing and Remote Access Service. It is a suite of network services in the Windows Server family that enables a server to perform the services of a conventional router.It is also a Windows proprietary server role, that supports remote user or site to site connectivity by using virtual private network or dial-up connections. So using RRAS we can convert a regular Windows Server as VPN server. Microsoft RRAS server and VPN client supports PPTP, L2TP, IPSec, SSTP and IKEv2 based VPN connections. Using RRAS as VPN remote users can connect to their company organisation networks internally and securely over public internet.

L2TP ( Layer 2 Tunneling Protocol )

L2TP or Layer 2 Tunnelling Protocol is a tunnelling protocol which originated by the merger of Microsoft (PPTP) and Cisco L2F. By default L2TP does not provide strong encryption or authentication by itself. So we use another protocol called IPsec in conjunction with L2TP. IPsec stands for Internet Protocol security. The IPsec protocol provides very strong encryption to data exchanged between the VPN server and with the VPN client machine.

When setting up a more secure VPN tunnels we commonly use L2TP along with IPsec. L2TP/IPsec together supports either computer certificates or a Pre-shared key as the authentication method. The Ports need to Open is UDP ports 500, 4500, 50 and 1701.

System Configuration We Used.

Used Windows server 2019 which is covert as a VPN SSTP server.

Used Windows 10 client PC for connecting to Windows VPN server 2019.

Another thing is we are settings up this SSTP VPN on windows server 2019 which only have one Network interface. So this blog article can be implemented on Most of VPS ( Virtual Private Server) provided by Hosting Providers or with the Cloud Windows VMs.

Additionally we are using the Pre-shared key as the authentication method when enabling L2TP/IPsec.

Here I have divided the whole steps in to different parts. Lets get started. Even though we are performing the install on Windows server 2019, you can refer this article for Windows server 2016 and windows server 2012.

Part:1 Install Remote Access Server role on Windows Server 2019

Log into the Windows Server 2019 > Click Windows Start Icon >> Click Server Manager.

Click Add Roles And Features

Click Next

Choose the Installation Type as ” Role based or feature based installation and click Next.

From Server selection, choose “select a server from the server pool” and click Next.

From Server Role choose ” Remote Access” and click Next.

Leave Features section as it is and click Next.

Click Next on Remote Access section.

Under Role Services choose “Direct Access and  VPN (RAS) and Routing and click Next. A popup window will appear for confirming the features that need to be installed for Direct Access and VPN. Confirm it by clicking “Add Features”.

Under Web Server Role (IIS) Section click Next.

Under IIS Role services section leave the default one and Click Next.

Under Final Confirmation section click Install.

The Remote Access server role install will start automatically and normally it will get completed with in few Minutes. Once the installation succeeded click close.

Part:2 Create Additional Loopback Network Adaptor On Windows Server 2019

Its for skipping the error while running Configuring Remote Access Wizard and the error  will be like below.

Less than two network interfaces were detected on this machine. For standard VPN server configuration at least two network interfaces need to be installed. Please use custom configuration path instead.

Under Server Manager  click Tools >> Computer Management.

From Computer Management window Click  Device Manager >> Click VM name from Right side.

Under Actions tab >> Click “Add legacy Hardware”

A add Hardware wizard will open and click Next.

Choose option ” Install the hardware that I manually select from a list ” and click Next.

Choose “Network Adaptors” and click Next.

Choose “Microsoft” as Manufacturer  and ” Microsoft KM-TEST Loopback Adaptor ” as Model. Click Next.

Confirm the Install by clicking Next.

Once the install got completed close the install wizard by clicking Finish.

Now, we can confirm the new network adaptor install from the Computer Management panel itself. For that click Device Manager >> Click VM name >> Expand Network Adaptors, there we can see the newly added LoopBack Network adaptor available.

Part:3 Configuring Remote Access Service VPN on Windows Server 2019

From Server Manager Choose Remote Access >> Right click the Server name >> Choose Remote Access Management.

Under “Direct Access And VPN” Click “Run the Remote Access Setup Wizard”

The Configure remote Access wizard will open Click “Deploy VPN only”

In the Routing and Remote Access Console , right click server name and choose ” configure and Enable routing and remote access ” option.

Click Next on Routing and Remote access server  setup wizard.

Choose Virtual private network( VPN) access and NAT option. Click Next.

In the select Network Interface section, choose the network adaptor where our public IP configured and click Next.

In the IP address Assigned section, choose ” from a specified range of address” and Click Next. Here we are trying to define the private IP address that server give to remote VPN click PC after successful connection.

Click New button.

Give the starting and ending private IP range in the corresponding fields. Click Ok. We are giving IPs starting from 192.168.3.150 to 192.168.3.160.

Now we will see the assigned range and click Next.

In the Do you want to setup this server to work with a radius server question section, select “No, use Routing and Remote Access to authenticate connection requests” and Click next.

Click Finish on Completing the Routing and Remote Access server setup wizard.

Click Ok.

This completes the configuration of Routing and Remote Access Server. Now we can see a green up arrow next to server hostname and which shows the Routing and Remote access server service started successfully.

Part:4 Enabling L2TP/IPsec VPN on Windows Server 2019

Here as we said earlier we enable L2TP/IPsec using Pre-Shared Key through Routing and Remote Access Properties.

In Routing and Remote Access Manager >> right click Server name and choose Properties.

Under Security Tab , Enable “Allow custom IPsec policy for L2TP/IKEv2 Connection”. In the preshared key box give any key. Make sure a its complex one.  Click Apply and OK.

Also note down this key because we need to share this key with the vpn client users. Then only the VPN remote client connections over L2TP/IPsec will be successful. 

Confirm the restart of routing and remote access service by clicking Yes.

Part:5 Allow Remote Access to our VPN server through Public Network Adaptor.

For maintain the access to the VPN server over remote desktop we need to allow the remote access port over our public network adaptor itself through routing and remote access properties section. Otherwise we will loss the access to the server through remote desktop because we only have one Network interface available on server for both VPN traffic and for the remote access.

In the Routing and Remote Access Manager , Expand Server name >> Expand IPv4 >> Choose NAT >> Right Click Our Public Network Adaptor and choose Properties.

Select ” Remote Access” , A pop up window will appear, in the Private Address filed give our server public IP address and click OK.  After that click Apply and OK.

If you have different RDP port, you need to create a new allow rule by clicking add option.

Part:6 Allow VPN remote access for the Users.

In this part we are giving a existing user on VPN server for remote access. Then only if we give the logins of these server users to remote VPN clients, they can successfully connect to server through VPN.

Go to the Computer Management Section >> Expand Local users and Groups >> Choose Users >> Right click a user where we wish to give VPN access and choose properties.

Under “Dial- In” tab >> Choose “Allow Access”. Click Apply and Ok.

Part:7 Allow VPN ports on Windows Firewall.

In this part we are allowing the ports used by the VPN server for communication on windows firewall. Otherwise the remote VPN clients won’t be able to communicate with the VPN server.

Now issue below power shell commands to allow ports in windows firewall.

Copy to Clipboard

Now if we look at  the windows firewall inbound section , we can see the ports are allowed.

This Completes the L2TP/IPsec VPN server setup on Windows server 2019. Now Lets Proceed with the Remote VPN Client Windows 10 PC setup and Try to Establish a VPN server connection.

Step:8 Test L2TP/IPsec VPN configuration.

For that , lets add VPN connection. For that open Network and Internet settings.

Under VPN >> Click Add a VPN connection.

Choose VPN Provider as Windows built in

In Connection Name field , give any Name

In Server name or Address field give VPN Server IP

Select VPN type as L2TP/IPsec with Preshared Key

In the Preshared Key box give our same Preshared key used  in the server at the Part:4

Type of sign in info as Username and Password

Gave our VPN username and password. Click Save.

Click connect for our saved VPN client settings.

Now we will see the VPN status as connected.

Two other ways to confirm the VPN connection is successful is go back to VPN server 2019 and Open Routing and Remote Access Manager >> From there Expand our server name >> Choose Remote Access client, and in the right side we can see a active connection.

Another option to confirm the successful VPN connection is , open a browser in Windows 10 PC and search the what is my IP and it will show the public ISP IP as VPN server IP. Which means all the internet traffic from client side is routing through our VPN server.

This Concludes the settings up L2TP/IPsec VPN  on Windows server 2019. I hope this blog article is informative. Leave your thoughts in the comment box.

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