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What is L2TP? Understanding the Role of L2TP in Network Technologies

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11 min read

The Layer 2 Tunneling Protocol (L2TP) is a network protocol that makes it possible to create virtual private networks (VPNs) by encapsulating data packets from one network to another. L2TP, which was created by combining Microsoft's Point-to-Point Tunneling Protocol (PPTP) with Cisco's Layer 2 Forwarding Protocol (L2F), enables the establishment of private, secure connections across public networks.

In the OSI model, L2TP functions at the data link layer, or Layer 2, which is in charge of creating and preserving direct connections between devices in a network. L2TP makes it easier to create encapsulated connections, or tunnels, that are used to transfer data privately over public networks like the Internet.

It's crucial to remember that L2TP lacks authentication and encryption capabilities. L2TP is frequently used with Internet Protocol Security (IPsec), which offers authentication and encryption features, to provide a safe connection. This combination, known as L2TP/IPsec, offers a reliable and secure VPN solution when used in tandem.

In conclusion, L2TP is a network protocol that enables data packet tunneling between networks to create virtual private networks (VPNs). It is frequently used with IPsec to provide private and secure connections across open networks, like the Internet.

Much more about L2TP may be found in this article under the topics below.

  • How Does L2TP Work?
  • How do the Ports of L2TP Operate?
  • What Are the Advantages of Using L2TP for VPN (Virtual Private Network) Connections?
  • How Does L2TP Differ from Other Tunneling Protocols Like PPTP and SSTP?
  • What Encryption Mechanisms Are Commonly Used with L2TP to Secure Data Transmission?
  • What Are the Key Components of an L2TP Connection?
    1. L2TP Tunnel
    2. L2TP Access Concentrator (LAC)
    3. L2TP Network Server (LNS)
    4. PPP (Point-to-Point Protocol)
    5. Authentication Protocols (e.g., PAP, CHAP)
    6. Session ID
    7. UDP (User Datagram Protocol)
    8. IPsec (Internet Protocol Security)
  • How Does L2TP/IPsec Compare to Other VPN Protocols in Terms of Security and Performance?
  • Are There Any Common Issues or Challenges Associated with Implementing L2TP in a Network?
  • What Are the Recommended Best Practices for Configuring L2TP on Routers and VPN Servers?
  • Can L2TP Be Used in Conjunction with Other Protocols Like IKEv2 for Enhanced Security?

How Does L2TP Work?​

In order to provide private and secure communication between devices over public networks like the internet, L2TP creates virtual private networks, or VPNs. By encapsulating data packets from one network and tunneling them to another, L2TP is able to do this. Here's a detailed breakdown of how L2TP functions:

  1. Making a Control Connection: Before establishing a VPN tunnel, a control connection needs to be made by the L2TP client and the L2TP server. The L2TP control protocol, which runs over User Datagram Protocol (UDP), is used for this control connection. The L2TP tunnel must be managed and kept up to date by the control connection.
  2. Tunnel Creation: The L2TP client and server discuss the settings for establishing a secure tunnel once the control connection has been established. Tunnel IDs, which are distinct integers provided to every endpoint to identify separate tunnels, are among these factors.
  3. Session Creation: The actual data traffic can be carried by one or more sessions generated inside the L2TP tunnel. For every data link that connects the client and the server, a session is created. Every session has a unique session identifier, much like with tunnels.
  4. Data Encapsulation: By appending L2TP headers to the original data packets, L2TP wraps the data packets coming from the client's network. Through this procedure, the original data is effectively concealed within a new packet that may be safely delivered over the public network.
  5. Data Transmission: Using the VPN tunnel that has been set up, the encapsulated data packets are sent from the L2TP client to the L2TP server. Even though the data is traveling across a public network, it stays private and safe while it goes via the tunnel.
  6. Data Decapsulation: The L2TP server removes the L2TP headers and extracts the actual data packets from the encapsulated packets once they arrive at the server. The intended recipient inside the server's network is then reached by forwarding these data packets.
  7. Tunnel and Session Teardown: The L2TP client and server can terminate the sessions and tear down the tunnel when the data transfer is finished or when the VPN connection is no longer required. Along with the VPN connection being stopped, the control connection is closed.

To summarize, L2TP functions by means of control connections, tunnels, and sessions, packet encapsulation, data transmission over the VPN tunnel, packet decapsulation upon arrival at the destination, and tunnel dismantling upon termination of the connection. L2TP offers a secure and private VPN option when combined with IPsec.

L2TP allows endpoints to be located on separate computers by using packet-switched network connections. Long-distance costs are eliminated if the circuit concentrator is local. Reliability, stability, compatibility, configurability, and defense against man-in-the-middle attacks are other advantages. Additionally, L2TP supports the range of authentication methods that PPP offers. This covers CHAP, the Microsoft Challenge-Handshake Authentication Protocol, and the Password Authentication Protocol. Using L2TP to add further security on top of IP security (IPsec) is another method for authenticating a tunnel's ends. L2TP is not without its problems. These include slower speeds, fewer ports supported, and transmission failure brought on by mismatched security keys.

How do the Ports of L2TP Operate?​

Point-to-Point Tunneling Protocol is extended by Layer Two Tunneling Protocol (L2TP), which utilizes UDP port 1701. IPSec and L2TP are frequently used to create virtual private networks (VPNs).

L2TP is frequently used in conjunction with IPsec due to its intrinsic lack of secrecy. This is established in IETF RFC 3193 and is known as L2TP/IPsec. The following steps are involved in configuring an L2TP/IPsec VPN:

  1. IPsec security association (SA) negotiation, usually using Internet key exchange (IKE): X.509 certificates, public keys, or shared passwords (also known as "pre-shared keys") are often used on both ends for this via UDP port 500, while alternative keying techniques are possible.
  2. Implementation of transport mode encapsulating security payload (ESP) communication: ESP has the IP protocol number 50 (as opposed to TCP's 6 and UDP's 17). A secure channel has been created up to this stage, but tunneling is not occurring.
  3. The SA endpoints' negotiation and creation of the L2TP tunnel: The real parameter negotiation happens inside the IPsec encryption over the secure channel of the SA. UDP port 1701 is used by L2TP.
  4. L2TP packets between the endpoints are encapsulated by IPsec after the procedure is finished: The original source and destination IP addresses are encrypted within the packet because the L2TP packet is wrapped and concealed within the IPsec packet. Moreover, since IPsec data is only encrypted and stripped at the endpoints, it is not required to open UDP port 1701 on firewalls between the endpoints. This is because inner packets are not processed until after this process.

When referring to L2TP/IPsec, the phrases "tunnel" and "secure channel" may cause misunderstandings. A route that enables unopened packets to be sent across networks is referred to as tunnel mode. It permits the delivery of L2TP/PPP packets across IP in this instance. A connection where full data confidentiality is ensured is referred to as a secure channel. IPsec offers a secure channel initially in L2TP/IPsec, followed by L2TP's tunnel. When using an L2TP tunnel, the tunnel protocol specified by IPsec is not utilized.

What Are the Advantages of Using L2TP for VPN Connections?​

To help you grasp how L2TP fits into the bigger picture, let's briefly go over the following advantages of using L2TP.

  • Robust security using IPSec: Private and secure data should be maintained when IPSec and Layer 2 tunneling protocols are used. Strong encryption that is nearly impenetrable is provided by IPSec. Though there is no concrete proof that the protocol was breached, there are allegations that the NSA broke IPSec.
  • Simple to operate: When compared to other VPN protocols, L2TP installation is rather simple. All of the main operating systems have a tunneling protocol. For example, users may quickly set up an L2TP VPN using Microsoft Windows' Network Settings.
  • The adaptability of Layer 2 networks: Compared to Level 3 VPNs, Level 2 connections offer a few advantages. Infrastructure may be shared more readily by businesses across several locations. Additionally, it is simpler to move the architecture of virtual machines across real devices as needed. PPTP can only handle IP tunnels; in contrast, L2TP can use a range of tunnel media.
  • Quickness: The speed of the Layer 2 Tunneling Protocol is well-known. L2TP connections are frequently just as fast as unencrypted ones.
  • Compatibility: L2TP is a rather flexible solution because it can be applied to practically all of the popular platforms. The majority of devices and operating systems support L2TP natively, making it incredibly simple to use without requiring the installation of extra software.
  • Dependability: L2TP is regarded as dependable since it can sustain connections even in the event of suboptimal network circumstances.
  • Perfect for Remote Access: L2TP works well for setting up business VPNs that let workers access company networks from a distance, in addition to being a strong choice for personal VPNs.
  • Stable Connections: L2TP is well-known for its dependability, which makes it a fantastic option for customers that value uninterrupted and constant VPN service.

How Does L2TP Differ from Other Tunneling Protocols Like PPTP and SSTP?​

The differences between L2TP and other tunneling protocols lik PPTP and SSTP are explained in the following sections.

What are the Differences Between L2TP and PPTP?​

When it comes to data integrity and authentication of origin verification, two features that prevent hackers from breaching the system, L2TP outperforms PPTP in many ways. However, it operates more slowly than PPTP because of the extra overhead needed to maintain this higher level of security.

In 1999, Layer 2 Tunneling Protocol (L2TP) was first made available as a collaborative effort between Microsoft and Cisco. It may be used to create VPN connections, much like PPTP. Similar to PPTP, it may be used in conjunction with IPsec to encrypt data transferred between a VPN client and server, but it does not authenticate or encrypt data on its own.

L2TP was developed as PPTP's upgrade. It fixes several flaws in it, such as the shoddy encryption. Moreover, it operates via UDP rather than TCP for quicker VPN connection speeds.

When used with IPsec, L2TP encrypts your data using AES encryption in addition to encasing it to be sent over a secure tunnel. Compared to PPTP, this is a vast improvement. Even data tampering while transmission is prevented, as demonstrated by the "Bit Flipping" vulnerability in PPTP. For instance, although PPTP can only tunnel across IP networks, L2TP may employ a range of tunnel media.

Additionally, L2TP allows several tunnels, each with a different quality of service, to connect two endpoints. One tunnel between two endpoints is supported by PPTP.

Four bytes make up a compressed L2TP header, while six bytes make up a compressed PPTP header.

What are the Differences Between L2TP and SSTP?​

The VPN protocol known as Secure Socket Tunneling Protocol (SSTP) is thought to provide the best level of security since it uses 256-bit encryption and 2048-bit key certificates for authentication. Because it uses TCP port 443, which is also used for Secure Socket Layer (SSL) transmissions, SSTP is used instead of other VPN protocols like PPTP and L2TP. It works well in places where network access is prohibited.

Originally published in 2008 as part of Windows Vista Service Pack 1, SSTP was a further upgrade to the antiquated PPTP protocol. These days, it works with Linux, macOS, and the majority of BSD versions.

What Encryption Mechanisms Are Commonly Used with L2TP to Secure Data Transmission?​

While L2TP offers a method for data tunneling between two endpoints, it does not include encryption or security features in and of itself. By itself, Layer 2 Tunneling Protocol (L2TP) cannot offer encryption. The Internet Protocol Security (IPsec) protocol suite is frequently used in tandem with L2TP connections to improve the security of data transmission.

The protocol that results from combining L2TP with IPsec is frequently referred to as "L2TP/IPsec". IPsec enhances the L2TP tunnel with robust encryption, authentication, and data integrity checks, enhancing the security of data transferred across the connection.

Other encryption techniques are also supported by L2TP to provide safe data transfer via the tunnel. Among the encryption protocols that are often used with L2TP are:

  1. Internet Protocol Security (IPSec): One popular encryption protocol for L2TP is IPSec. It offers robust authentication and encryption features to protect the data being transferred across the tunnel. L2TP packets are frequently protected by IPsec since it offers secrecy, authentication, and integrity. L2TP/IPsec is the colloquial name for these two protocols (explained below).
  2. Point-to-Point Tunneling Protocol (PPTP): Another popular encryption protocol for L2TP is PPTP.

What Are the Key Components of an L2TP Connection?​

Most L2 data types may be sent over an IP or Layer Three (L3) network using L2TP. The procedure starts a tunnel via the internet between an L2TP network server (LNS) and an L2TP access concentrator (LAC). This makes it easier to encapsulate and transport a Point-to-Point Protocol (PPP) connection layer across the internet.

Using a public switched telephone network (PSTN) or an Integrated Services Digital Network (ISDN), the end user establishes a PPP connection with an ISP. An assortment of different protocols and parts that cooperate to create and manage a VPN enable L2TP to function. The main parts of L2TP are as follows:

  1. L2TP Tunnel: The L2TP client and server discuss the settings for establishing a secure tunnel when the control connection is established. Tunnel IDs, which are distinct integers provided to every endpoint to identify separate tunnels, are among these factors.
  2. L2TP Access Concentrator (LAC): Data from distant devices is received by the LAC, which securely forwards it to the LNS. To send data frames, the LAC establishes a Point-to-Point (PPP) connection. In order to transit L2TP traffic over the internet, LACs can be incorporated into ISPs or they can live in enterprise data centers.
  3. L2TP Network Server (LNS): The L2TP Network Server (LNS) is in charge of cutting off incoming L2TP connections and sending user data to the proper network location.
  4. PPP (Point-to-Point Protocol): A link layer tunnel between a target L2TP server endpoint (L2TP Network Server, or LNS) and a requesting L2TP client (L2TP Access Concentrator, or LAC) is supported by Layer 2 Tunneling Protocol (L2TP), a tunneling protocol that extends Point-to-Point Protocol (PPP).
  5. Authentication Protocols (e.g., PAP, CHAP): L2TP authenticates user identities using PPP security features like CHAP and PAP.
  6. Session ID: The peer along an L2TP tunnel assigns the tunnel ID and session ID found in an L2TP message header to identify a tunnel and a session, respectively. On a single L2TP tunnel, messages with distinct session IDs but the same tunnel ID are multiplexed.
  7. UDP (User Datagram Protocol): An L2TP frame is encased inside a User Datagram Protocol (UDP) packet, which is encapsulated inside an IP packet, to form an L2TP tunnel.
  8. IPsec (Internet Protocol Security): When L2TP and IPSec are combined, the data payload is protected.

1. L2TP Tunnel​

A User Datagram Protocol (UDP) datagram contains the whole L2TP packet, including the content and L2TP header. Transmission using UDP (as opposed to TCP) has the benefit of not having the "TCP meltdown problem." PPP sessions are frequently carried out via an L2TP tunnel. By itself, L2TP cannot offer robust authentication or secrecy. L2TP packets are frequently protected by IPsec since it offers secrecy, authentication, and integrity. L2TP/IPsec is the colloquial name for these two protocols (explained below). The L2TP network server (LNS) and the L2TP access concentrator (LAC) are the two ends of an L2TP tunnel. New tunnels are awaited by the LNS. The network communication between the peers is bidirectional as soon as a tunnel is created. Higher-level protocols are then sent across the L2TP tunnel for networking purposes. For every higher-level protocol, like PPP, an L2TP session is created inside the tunnel to enable this. Sessions are started by the LNS or the LAC. L2TP isolates the traffic for each session, allowing numerous virtual networks to be established via a single tunnel. Control packets and data packets are the two types of packets that are transferred via an L2TP tunnel. For control packets, L2TP offers dependability characteristics; however, it offers no reliability for data packets. If reliability is required, it must be supplied via the layered protocols that operate inside each L2TP tunnel session. Using a common infrastructure, such as the Internet or a service provider's network, L2TP enables the development of a virtual private dial-up network (VPDN) to link a remote client to its corporate network.

2. L2TP Access Concentrator (LAC)​

The part, which is a server or a network device, that receives incoming VPN connections is called an L2TP Access Concentrator (LAC). Moreover, it starts and maintains the L2TP tunnels for distant clients. L2TP access concentrators, or LACs, are capable of L2TP as well as PPP. Usually, access services are provided primarily to PPP customers via a network access server (NAS) housed at a nearby ISP. Situated between an LNS and a distant system, a LAC serves as the terminus of an L2TP tunnel. Using L2TP, it wraps packets received from a distant system before sending them to the LNS. After receiving packets from the LNS, it decapsulates them before sending them to the designated distant system.

3. L2TP Network Server (LNS)​

The LNS serves as the PPP session termination point and is located at the opposite end of the L2TP tunnel. It facilitates encrypted traffic access to network resources and serves as a bridge between public and private networks.

PPP and L2TP can both be used with an L2TP network server (LNS). Typically, it is an edge device connected to a business network.

The other endpoint of an L2TP tunnel is called an LNS. It is the logical endpoint of a PPP session that the LAC has tunneled. By creating a tunnel, L2TP extends a PPP session's termination point from a NAS to an LNS.

4. PPP (Point-to-Point Protocol)​

Most L2 data types are sent over an IP or Layer Three (L3) network using L2TP. The procedure starts a tunnel via the internet between an L2TP network server (LNS) and an L2TP access concentrator (LAC). This makes it easier to encapsulate and transport a Point-to-Point Protocol (PPP) connection layer across the internet.

Using a public switched telephone network (PSTN) or an Integrated Services Digital Network (ISDN), the end user establishes a PPP connection with an ISP.

Little is known about L2TP. Prior iterations could only carry PPP. But this restriction is no longer in place. PPP establishes an encapsulating mechanism for multiprotocol packet transmission across L2 point-to-point networks.

In this case, PPP operates over a connection that the user establishes with the network access server (NAS) using ISDN, Asymmetric Digital Subscriber Line, Plain Old Telephone Service, or other services. The L2 and PPP session endpoints in this arrangement are located on the same NAS.

5. Authentication Protocols (e.g., PAP, CHAP)​

For distant users, L2TP offers dependable, safe, and easy access services with features like strong security and flexible identity authentication. To do this, L2TP authenticates user identities using PPP security features like CHAP and PAP.

Passwords are used to verify users using PAP, or password authentication protocol, a point-to-point (PPP) authentication technique. It is a password-based authentication mechanism that is part of the RFC 1334 internet standard.

Data is not encrypted while using PAP. It is transmitted in plain text to the authentication server. PAP authenticates users via a two-way handshake based on the username and password they have given.

During an online session, the user is regularly re-authenticated using the identity verification technique known as the Challenge-Handshake Authentication Technique (CHAP). When used correctly, CHAP is much more secure than the Password Authentication Protocol (PAP) and resistant to replay attacks.

Transmitting mutual secrets between the service and the party requesting access is not necessary for CHAP to function. The creation of a shared secret is necessary, but in order to use a service, a cryptographic "handshake" must be established between the service and the requester. The party who has previously established a connection can then be re-authenticated within the same session by receiving further challenges from the service. Replay assaults are impossible because subsequent tasks change progressively from one another.

By including a three-way handshake procedure, CHAP can provide the PPP session with an additional degree of protection. PAP is a common login process that is used to authenticate users using PPP.

6. Session ID​

The actual data traffic might be carried by one or more sessions generated inside the L2TP tunnel. For every data link that connects the client and the server, a session is created. Every session has a unique session identifier, much like with tunnels.

A peer along an L2TP tunnel assigns a tunnel ID and a session ID to identify a tunnel and a session, respectively, in an L2TP message header. Multiplexing occurs on a single L2TP tunnel between messages with distinct session IDs and the same tunnel ID.

7. UDP (User Datagram Protocol)​

An L2TP frame is encased inside a User Datagram Protocol (UDP) packet, which is encapsulated inside an IP packet, to form an L2TP tunnel. The endpoints of the connection are identified by the source and destination addresses of an IP packet. The composite IP packet can employ IPSec protocols since IP is the outside encapsulating protocol. This safeguards the information passing via the L2TP tunnel. The Internet Key Exchange (IKE) protocol, Authentication Header (AH), and Encapsulated Security Payload (ESP) may then be used simply.

In IP-based networks, the User Datagram Protocol (UDP) facilitates connectionless datagram transfer by offering a point-to-point, transaction-based point-to-point communication service at the transport layer. Furthermore, UDP is distinguished by its inability to ensure packet delivery.

The UDP protocol is used by programs that transfer small quantities of data, usually across local networks and in real time. Applications that employ the user datagram protocol as a best-effort tool, simulcasting, and programs with their own methods for dependable transmission are among the numerous uses for the UDP protocol. As a result, DNS searches, video or audio streaming, VPN connections, and RIP (Routing Information Protocol) may all be accomplished using UDP protocols.

8. IPsec (Internet Protocol Security)​

When L2TP and IPSec are combined, the data payload is protected. Additionally, when used with IPSec, it may employ encryption keys up to 256 bits in length using the 3DES technique. L2TP utilizes UDP ports 500 +, 4500, and 1701 after partnering with IPSec. However, it utilizes TCP port 1701 properly before pairing. The standard port L2TP does not support port swapping.

Some L2TP headers are included in the construction of an L2TP data packet. IPSec ESP Trailer, IPSec Authentication Trailer, L2TP Header, IP Header, PPP Header, PPP Payload, and UDP Header are a few of them.

How Does L2TP/IPsec Compare to Other VPN Protocols in Terms of Security and Performance?​

A VPN tunneling protocol called L2TP/IPsec establishes a connection between you and a VPN server. L2TP depends on the IPsec suite to encrypt your traffic and provide privacy and security, even though it does not offer encryption or authentication in and of itself. L2TP is widely accessible and may be tailored to satisfy unique security requirements, despite its restrictions.

Although Layer 2 Tunneling Protocol (L2TP) lacks encryption, when combined with IPSec, it is widely considered secure. Standard IPSec encryption encapsulates data twice. Because L2TP supports a number of encryption techniques, you may customize the security level to meet your needs. Data is double-encapsulated using L2TP/IPSec, with encryption provided by the IPSec standard protocol.

PPTP is not as good an alternative as L2TP/IPSec if you want to create your own VPN. Nevertheless, additional setup is needed to get over NAT firewalls, which might make things quite difficult. Because L2TP does not have effective ways to get beyond firewalls, administrators who are interested in surveillance may choose to restrict it.

When used with IPsec encryption, L2TP is deemed safe. Connection, encryption, and security are all included in one package when using L2TP with IPsec. Although there have been security controversies, it is still extensively used and regarded as secure by most. Keep abreast of any weaknesses and put the required security measures in place to ensure a secure VPN connection.

L2TP/IPSec performance varies a great deal. On the one hand, the protocol allows multi-threading, which should increase speeds, and encryption and decryption take place in the kernel. However, the fact that this VPN protocol encodes data twice might cause it to lag noticeably. The performance of L2TP/IPSec might be negatively impacted by its considerable slowdown due to the use of double encapsulation.

Since most consumer systems support L2TP, setup and support are straightforward. However, slower rates may arise from L2TP's twofold encapsulation of data when compared to protocols that simply wrap data once.

Are There Any Common Issues or Challenges Associated with Implementing L2TP in a Network?​

Yes, L2TP has a number of drawbacks, especially when used as a stand-alone virtual private network (VPN) creation protocol. Among the principal disadvantages of L2TP are as follows:

  • Absence of Built-in Encryption: L2TP lacks the authentication and encryption mechanisms that are necessary to protect data sent over public networks. L2TP has to be used in conjunction with Internet Protocol Security (IPsec), which provides authentication and encryption, to provide a secure VPN solution. But depending too much on IPsec can make things more complicated and possibly affect how well things work.
  • Performance Overhead: The additional overhead introduced by the encapsulation and encryption operations when L2TP is paired with IPsec might have an impact on network performance. Data packets that have been double-encapsulated may experience higher delay and lower throughput, especially on networks with constrained capacity or processing power.
  • Problems with NAT Traversal: L2TP may have problems when utilized in networks that have Network Address Translation (NAT) turned on, which is a typical setup for a lot of household and business networks. As data packets move through the router, NAT affects IP addresses; this adjustment may cause issues for L2TP/IPsec. Nevertheless, these problems have been resolved in more recent L2TP/IPsec implementations by employing NAT traversal strategies such as UDP encapsulation.
  • Complexity: Compared to certain other VPN systems, L2TP/IPsec VPN implementation and management might be more complicated. This complexity results from the need for additional knowledge and resources for setting and maintaining the distinct L2TP and IPsec components.
  • Firewall Compatibility: Due to L2TP/IPsec's use of particular ports and protocols, some firewalls may be unable to allow it. Users in these situations might have to adjust their firewall settings or switch to a different VPN service that works better with their network.

To sum up, L2TP has a number of drawbacks, such as complexity, NAT traversal difficulties, lack of built-in encryption, speed overhead, and possible firewall compatibility concerns. Notwithstanding these shortcomings, L2TP may nonetheless offer a reliable and secure VPN solution for a variety of use cases when paired with IPsec.

A safe protocol for remote access VPNs is L2TP over IPSec. It offers an encrypted, safe connection via the internet for two or more devices. In order to provide safe and smooth connections for distant workers, several firms utilize this protocol.

Even though L2TP is a more widely used protocol for remote access VPNs than IPSec, it is not flawless. The following list contrasts L2TP over IPSec with other protocols:

  • Due to security flaws, the older PPTP (Point-to-Point Tunneling Protocol) protocol is no longer advised.
  • A popular open-source protocol with robust encryption and security is called OpenVPN. On the client and server, nevertheless, it necessitates the installation of extra software.
  • Compared to L2TP over IPSec, IKEv2 (Internet Key Exchange version 2) is a more recent protocol that provides higher speeds and more stability. All gadgets might not support it, though.

The following advice can help you set up L2TP over IPSec securely:

  • Make use of robust authentication techniques such as EAP-TLS or MS-CHAP v2.
  • Employ secure pre-shared keys and maintain their secrecy.
  • Turn off any unneeded protocols and authentication techniques.
  • Update the client and VPN server software on a regular basis.
  • Keep an eye on your VPN records for any odd behavior.

How to Configure L2TP over IPSec?​

A VPN server and a VPN client are the two essential components needed to configure L2TP over IPSec. We'll use Windows 10 as the VPN client and Windows Server 2019 as the VPN server in our example. To configure L2TP over IPSec, take the following steps:

  1. Step 1: Install the Remote Access Role On your Windows Server 2019 computer, open Server Manager and select Add Roles and Features. Click Next after selecting the remote access role. Click Next after choosing Direct Access and VPN (RAS) on the Role Services screen. To install the role, click Install at the end.
  2. Step 2: Set Up the VPN Server: Launch the Routing and Remote Access interface after installing the Remote Access role. Configure, Enable Routing, and Remote Access may be selected by right-clicking on the server name. Configure the VPN and NAT services by following the instructions. Configure the security settings and choose L2TP over IPSec.
  3. Step 3: Set Up User Authentication: Click the Security tab and choose Authentication Methods in the Routing and Remote Access dashboard. Select MS-CHAP v2 and leave the other options unchecked. To save the adjustments, click OK.
  4. Step 4: Set Up the VPN Client: Navigate to Settings > Network & Internet > VPN on the Windows 10 client. After selecting Add a VPN connection, type the IP address or server name. Under VPN type, choose L2TP/IPSec with a pre-shared key. Click Save after entering the login, password, and shared key.
  5. Step 5: Make a VPN connection: After selecting the recently established VPN connection, click Connect. You ought to be able to establish a successful connection to the VPN server if everything is set up properly.

Can L2TP Be Used in Conjunction with Other Protocols Like IKEv2 for Enhanced Security?​

Yes, for increased security, L2TP may be used in conjunction with other protocols. By itself, Layer 2 Tunneling Protocol (L2TP) cannot offer encryption. The Internet Protocol Security (IPsec) protocol suite is frequently used in tandem with L2TP connections to improve the security of data transmission.

The protocol that results from combining L2TP with IPsec is frequently referred to as "L2TP/IPsec." IPsec enhances the L2TP tunnel with robust encryption, authentication, and data integrity checks, enhancing the security of data transferred across the connection.

IKEv2 can swiftly swap networks and re-establish a VPN connection when it is momentarily dropped, and it typically operates more rapidly than L2TP. Although IPSec and L2TP are frequently used together for encryption, IKEv2 was built from the ground up to be compatible with IPsec and is regarded as a very secure protocol. While IKEv2/IPsec and L2TP/IPSec are both extensively supported on a wide range of devices, the IKEv2 protocol occasionally needs other software. Firewall traversal can also be a problem for L2TP and IKEv2. IKEv2 is still a more sophisticated VPN protocol than L2TP in spite of its shortcomings.

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