The vulnerability is due to insufficient validation of l2tp packets. Ip networking and the layer 2 tunneling protocol l2tp are used within a wireless data network to transport data between an iwf and a point where an rlp is terminated. A virtual private lan service vpls encapsulates a layer 2 ethernet frame within a layer 3 ip packet. A family of network control protocols ncps for establishing and configuring different network layer protocols. Layer two tunneling protocol l2tp is an extension of the pointtopoint tunneling protocol used by an internet service provider to enable the operation of a virtual private network over the internet.
A tunnel is not encrypted by default, it relies on the tcpip protocol chosen to determine the level of. This definition describes the meaning of ssl vpn secure sockets layer virtual private network and how it is used to protect remote users internet connections, as well as how it compares to. Rather, it relies on an encryption protocol that it passes within the tunnel to provide privacy. The combination of these two protocols is often referred to as l2tpipsec, a protocol that supports up to 256bit encryption and the 3des algorithm.
L2tp is owned by cisco and is considered to be a better version of pptp. Layer 2 protocol tunneling ccie cisco certified expert. Find out information about layer two tunneling protocol. Rfc 7886 was draftietfl2tpextsbfddiscriminator advertising seamless bidirectional forwarding detection sbfd discriminators in the layer two tunneling protocol version 3 l2tpv3. L2tp was developed by microsoft and cisco as a combination between pptp and l2flayer 2 forwarding.
Computer dictionary definition of what l2tp layer 2 tunneling protocol means, including related links, information, and terms. Configuring support for layer 2 protocol tunneling. Specifies the layer 2 tunneling protocol l2tp ipsec extensions, which allows ip, ipx, or netbeui traffic to be encrypted and then sent over any medium that supports pointtopoint ppp point to point protocol rfc1661 datagram delivery, such as ip, x. The lac sits between an lns and a remote system and forwards packets to and from each. Layer two tunneling protocol extensions l2tpext documents. L2tp layer 2 tunneling protocol an ietf standard tunneling protocol for vpns, designed to tunnel ppp traffic over lans or public networks. A vulnerability in the layer 2 tunneling protocol l2tp parsing function of cisco ios and cisco ios xe software could allow an unauthenticated, remote attacker to cause an affected device to reload. Lac l2tp access concentrator device terminating calls to remote systems and. This can be pretty usefulfor example, lets say you have two remote sites and an application that requires that hosts are on the same subnet. In a regular protocol, the lower layer protocol encapsulates packets from the higher level protocol. As a tunneling protocol only, it doesnt provide any encryption of its own. A common misconception is that l2tp is an encryption protocol. L2f is part of the layer 2 tunneling protocol l2tp standard rfc 2661. In computer networking, layer 2 tunneling protocol l2tp is a tunneling protocol used to published in as proposed standard rfc, l2tp has its origins primarily in two older tunneling protocols for pointtopoint communication.
Enable layer 2 protocol tunneling l2pt on a vlan on switches that do not use the the enhanced layer 2 software els configuration style which includes ex2200, ex3300, ex4200, ex4500, and ex4450 switches. Layer 2 tunneling protocol l2tp is a computer networking protocol used by internet service providers isps to enable virtual private network vpn operations. Layer two tunneling protocol englishmalayalam dictionary. Vpn basics however, vendors have combined pptp with a similar protocol, cisco systems layer 2 forwarding protocol, to create l2tp, which they hope to present to the ietf for. Layer 2 tunneling protocol l2tp came about through a partnership between cisco and microsoft with the intention of providing a more secure vpn protocol. Found 0 sentences matching phrase layer two tunneling protocol. For l2tpv2 these l2 frames are pointtopoint protocol ppp layer 2 frames. L2tp has since been adopted for tunneling a number of other l2 protocols. Dieses feld definiert ob es sich um eine kontrollmitteilung wert 1 oder um daten wert 0 handelt. Pptp pointtopoint tunneling protocol pptp is not a standard tunneling protocol. L2tpv2 enables pointtopoint ppp frames to be totally encapsulated within network. Layer two tunneling protocol l2tp is an extension of the pointtopoint tunneling protocol pptp used by an internet service provider isp to enable the operation of a virtual private network vpn over the internet. Layer 2 tunneling protocol l2tp active discovery relay for ppp over ethernet pppoe.
Layer 2 tunneling protocol ssl certificate management site. In computer networking, layer 2 tunneling protocol l2tp is a tunneling protocol used to. Pointtopoint protocol ppp over an ip network for example. Tunneling protocol an overview sciencedirect topics.
Mar 10, 2018 layer 2 protocol tunneling can be used independently or to enhance 802. Microsoft developed pptp, whichlike l2tptunnels layer 2 ppp traffic over lans or public networks. A tunneling protocol used for secure nodetonode communications by internet service providers isps and other virtual private network vpn service providers in support of multiple, simultaneous tunnels in the network core. Short for layer 2 tunneling protocol, l2tp is a tunneling, session layer protocol, using the udp port 1701 on a vpn virtual private network. Effectively, a corporation uses a widearea network as a single large local area network. Information technology laboratory computer security resource center computer security resource center computer security resource center. How is layer 2 tunneling protocol version 3 abbreviated. L2tp is considered to be a more secure option than pptp, as the ipsec protocol which holds more secure encryption algorithms, is utilized in conjunction with it. If you disable layer 2 protocol tunneling on a port, the disabled protocols function the same way they were functioning before layer 2 protocol tunneling was enabled on the port. L2tp is defined as layer 2 tunnel protocol frequently. An attacker could exploit this vulnerability by sending a crafted l2tp packet to an affected device. L2tpv3 layer two tunneling protocol version 3 is a pointtopoint layer two over ip tunnel.
One of the oldest, yet still popular, vpn protocols is pointtopoint tunneling protocol, or pptp. Tunneling protocol article about tunneling protocol by the. Pointtopoint tunneling protocol pptp is a protocol set of communication rules that allows corporations to extend their own corporate network through private tunnels over the public internet. Layer 2 tunneling protocol l2tp ipsec extensions intellectual property rights notice for open specifications documentation technical documentation. L2f layer 2 forwarding a tunneling protocol that creates network access server nasinitiated tunnels for forwarding ppp sessions.
L2tp is defined in rfc 2661, layer two tunneling protocol l2tp. L2tpv3 layer 2 tunneling protocol version 3 acronymfinder. L2tp merges the best features of two other tunneling protocols. In this paper, we will focus on l2tp layer 2 tunneling protocol which is basically introduce to deploy the gateway and host mode. Like pptp, l2tp requires that the isps routerssupport the protocol. Virtual private networks washington university in st. The layer 2 tunneling protocol l2tp is a standard protocol for tunneling l2 traffic over an ip network. This means you can tunnel l2 protocols like ethernet, framerelay, atm, hdlc, ppp, etc. It really is a layer 5 protocol because it uses the session layer in the osi model. Cisco ios and ios xe software layer 2 tunneling protocol. In this protocol, ip packets of data are encapsulated and transmitted to the vpn server. Introduction the layer two tunneling protocol l2tp provides a dynamic mechanism for tunneling layer 2 l2 circuits across a packetoriented data network e.
The truth is, l2tp is a tunneling protocol and doesnt provide any form of encryption by itself. Layer 2 tunneling protocol l2tp is a hybrid of pptp and layer 2 forwarding l2f. A tunnel is not encrypted by default, it relies on the tcpip protocol chosen to determine the level of security. Ssl vpn secure sockets layer virtual private network. In contrast, a tunneling protocol encapsulates a packet of the same or lower layer. L2tp is one of the most widely used protocol to create a vpn connection between your device and a remote vpn server. What does layer 2 tunneling protocol actually mean. In computer networking, layer 2 tunneling protocol l2tp is a tunneling protocol used to support virtual private networks vpns. The layer 2 tunneling protocol l2tp allows the transmission of frames between two nodes. In computer networking, layer 2 tunneling protocol l2tp is a tunneling protocol used to support virtual private networks vpns or as part of the delivery of services by isps. Pptp creates an encrypted tunnel between the vpn server and the customers computer via tcp port 1723 as well as general routing encapsulation, also called gre. Definition of layer 2 tunneling protocol in the dictionary. Insofar as vpns are concerned, the definition in 2. Signaling of modemonhold status in layer 2 tunneling protocol l2tp.
Layer 2 forwarding protocol l2f da cisco e o pointtopoint tunnelling protocol pptp da microsoft. For example, a network layer 3 packet encapsulates a transport layer 4 packet, and a data link layer 2 packet encapsulates a network layer 3 packet. Find out inside pcmags comprehensive tech and computerrelated encyclopedia. Socksv5, pointtopoint tunneling protocol pptp, layer 2 transport protocol l2tp, and internet protocol security ipsec. Its assumed that all the configuration issues are preconfigured often by manual process.
Gtp version 2 is different to version 1 only in gtpc. L2tp stands for layer 2 tunneling protocol, and its like the name implies a tunneling protocol that was designed to support vpn connections. Layer 2 transport protocol how is layer 2 transport. Rfc 2661 layer two tunneling protocol l2tp ietf tools. Layer two forwarding l2f is a cisco tunneling protocol that uses virtual dialup networks for secure data packet transport. L2tp facilitates the tunneling of ppp packets across an intervening network in a way that is as transparent as possible to both endusers and applications. Packets sent from the lac to the lns requires tunneling with the l2tp protocol as defined in this document. Short for layer two 2 tunneling protocol, an extension to the ppp protocol that enables isps to operate virtual private networks vpns. In such a configuration, the l2 termination point and ppp session endpoint reside on the same. L2tpv3 stands for layer 2 tunneling protocol version 3. L2tp vpn everything about layer 2 tunneling protocol. Information and translations of layer 2 tunneling protocol in the most comprehensive dictionary definitions resource on the web. The differences between pptp, l2tpipsec, sstp and openvpn.
L2tp, as originally defined in rfc 2661, is a standard method for tunneling pointtopoint protocol ppp rfc1661 sessions. Versions 1 and 2 are each effectively two protocols, one for control called gtpc and one for user data tunneling called gtpu. L2tp is similar to the data link layer protocol in the osi reference model, but it is actually a session layer protocol. It does not include any encryption and relies on other methods to provide data security and privacy, such as ipsec. Pptp creates clientinitiated tunnels by encapsulating packets into ip datagrams for transmission over the internet or other tcpipbased networks.
L2tpv2 tunneling of ppp feature overview and configuration. In a remote access environment, l2tp allows either tunneling of remote access client ppp frames via a nas to a vpn gatewayconcentrator or. Aug 26, 2012 l2tp layer 2 tunneling protocol its another tunneling protocol that supports vpns. Rfc 3931 layer two tunneling protocol version 3 l2tpv3. It was introduced in 1995, and though newer protocols have since usurped its place as the greatest, many people and businesses still make use of pptp. L2f functionality is similar to the pointtopoint tunneling protocol pptp, which was developed by the microsoftled pptp forum. Apr 01, 2020 the layer 2 tunneling protocol l2tp launched in 1999 is an update on the point to point tunneling protocol pptp. A user datagram protocol udp port is used for l2tp. Defines l2tp avp attributes 53 modem onhold capable and 54 modem onhold status. Layer 2 tunneling protocol version 3 thelayer2tunnelingprotocolversion3featureexpandsciscossupportoflayer2vpns. Layer 2 tunneling protocol wikipedia, a enciclopedia livre. It uses the same authentication mechanisms as pptp but its tunneling protocol is advanced as it relies on ipsec for encryption. A link control protocol lcp for establishing, configuring, and testing the datalink connection.
Tunneling protocol article about tunneling protocol by. A user datagram protocol udp port is used for l2tp communication. Dec 03, 2018 pptp incorporates factors of the even older pointtopoint protocol, or ppp. Aug 18, 2011 layer 2 tunneling protocol l2tp is a computer networking protocol used by internet service providers isps to enable virtual private network vpn operations. Working groups are typically created to address a specific problem or to produce one or more specific deliverables a guideline, standards specification, etc. L2tpv3 is defined as layer 2 tunneling protocol version 3 frequently. Translation memories are created by human, but computer aligned, which might cause mistakes. It is a combination of the two protocols, the pptp of microsoft and the layer 2 forward l2f of cisco. Abstract this document describes the layer two tunneling protocol l2tp. Layer 2 tunneling protocol overview techlibrary juniper.
The difference between pptp and l2tp is that the second one provides not only data confidentiality but also data integrity. The radius feature overview and configuration guide. How pointtopoint tunneling protocol pptp works the. L2tpv2 layer 2 tunneling protocol l2tpv2 enables encapsulated layer 2 frames to be carried across the network. Layer two tunneling protocol article about layer two. Microsoft publishes open specifications documentation this documentation for protocols, file formats, data portability, computer languages, and standards support. Within the discussion of content networking, we will. Layer two tunneling protocol commonly used are pptp, l2f, l2tp. A company no longer needs to lease its own lines for. In version 0, the signalling protocol the protocol which sets up the tunnels by activating the pdp context is combined with the tunneling protocol on one port. Rfc 2661 l2tp august 1999 l2tp access concentrator lac a node that acts as one side of an l2tp tunnel endpoint and is a peer to the l2tp network server lns. Ipsec, vpn, and firewall concepts computer science.
Layer 2 tunneling protocol l2tp is an advanced networking protocol that is used to support vpn services. L2tp is an open standard with mutlivendor interoperability and acceptance. Aug 25, 2017 the layer 2 tunneling protocol l2tp allows the transmission of frames between two nodes. Level data link control, l2tp layer 2 tunneling protocol, and pppoe pointtopoint protocol over ethernet provide such protocols. Layer 2 protocols 3 31 layer 2 protocols 3 pptp point to point tunneling protocol pptp ppp ip encapsulation for tcpip, ipx, and netbeui no encryption, but extended with rc4, pap, chap, and eap singlefactor authentication. Its ability to carry almost any l2 data format over ip or other l3 networks makes it. Some protocols are faster than the competition while others prioritize security. An ietf standard protocol for creating virtual private networks. Like pptp, it uses a single pointtopoint connection per session.1086 1272 275 1569 877 192 1267 1546 742 342 150 487 264 243 1073 426 1155 1545 983 705 1102 320 957 758 1227 15 293 1160 1288 1100 1425 841 1043 599 1491 194 267 713 953 382 274