A tunneling protocol is a network protocol which encapsulates one protocol or session inside another. Protocol A is encapsulated within protocol B, such that A treats B as though it were a data link layer. Tunneling may be used to transport a network protocol through a network which would not otherwise support it. Tunnelling may also be used to provide various types of VPN functionality such as private addressing. In networking, a communications protocol or network protocol is the specification of a set of rules for a particular type of communication. ... The data link layer is layer two of the seven-layer OSI model. ... A Virtual Private Network, or VPN, is a private communications network usually used within a company, or by several different companies or organizations, communicating over a public network. ...

Examples include:

Datagram-based: A packet is the fundamental unit of information carriage in all modern computer networks. ...

• L2TP (Layer 2 Tunneling Protocol)
• MPLS (Multi-Protocol Label Switching)
• GRE (Generic Routing Encapsulation)
• GTP (GPRS Tunnelling Protocol)
• PPTP (Point-to-Point Tunneling Protocol)
• PPPoE (point-to-point protocol over Ethernet)
• PPPoA (point-to-point protocol over ATM)
• IP in IP Tunneling (RFC 1853)
• IPsec
• IEEE 802.1Q (Ethernet VLANs)
• DLSw (SNA over IP)
• XOT (X.25 datagrams over a TCP)
• 6to4 (IPv6 over IPv4 as protocol 41)
• Teredo (IPv6 over UDP over IPv4)
• AYIYA (Anything In Anything, eg IPv6 over UDP over IPv4, IPv4 over IPv6, IPv6 over TCP IPv4 etc)
• Hamachi (IPv4 over UDP)

Stream-based: In computer networking, the Layer 2 Tunneling Protocol (L2TP) is a tunneling protocol used to support virtual private networks (VPNs). ... The Open Systems Interconnection Reference Model (OSI Model or OSI Reference Model for short) is a layered abstract description for communications and computer network protocol design, developed as part of the Open Systems Interconnect initiative. ... In computer networking and telecommunications, Multiprotocol Label Switching (MPLS) is a data-carrying mechanism, operating at a layer Layer3 below and in parallel to IP. It was designed to provide a unified data-carrying service for both circuit-based clients and packet-switching clients which provide a datagram service model. ... Generic Routing Encapsulation (GRE) is a tunneling protocol designed for encapsulation of arbitrary kinds of network layer packets inside arbitrary kinds of network layer packets. ... GPRS Tunnelling Protocol (or GTP) is a IP based protocol used within GSM and UMTS networks. ... The Point-to-Point Tunneling Protocol (PPTP) is a method for implementing virtual private networks. ... This article incorporates text translated from the corresponding German Wikipedia article as of December 2005 PPPoE, point-to-point protocol over Ethernet, is a network protocol for encapsulating PPP frames in Ethernet frames. ... In computing, the Point-to-Point Protocol, or PPP, is commonly used to establish a direct connection between two nodes. ... Ethernet is a frame-based computer networking technology for local area networks (LANs). ... PPPOA or PPPoA, Point-to-Point Protocol (PPP) over ATM, is a network protocol for encapsulating PPP frames in ATM AAL5. ... Asynchronous Transfer Mode, or ATM for short, is a cell relay network protocol which encodes data traffic into small fixed sized (53 byte; 48 bytes of data and 5 bytes of header information) cells instead of variable sized packets as in packet-switched networks (such as the Internet Protocol or... IPsec (IP security) is a standard for securing Internet Protocol (IP) communications by encrypting and/or authenticating all IP packets. ... IEEE 802. ... Systems Network Architecture (SNA) is IBMs proprietary networking architecture created in 1974. ... The Internet Protocol (IP) is a data-oriented protocol used by source and destination hosts for communicating data across a packet-switched internetwork. ... X.25 is an ITU-T standard protocol suite for WAN networks using the phone or ISDN system as the networking hardware. ... The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite. ... 6to4 (sometimes written 6 to 4) is a system that allows IPv6 packets to be transmitted over an IPv4 network. ... The Teredo Tunneling IPv6 over UDP through NAT protocol defines a method to access the IPv6 Internet from behind a NAT device. ... Anything In Anything (AYIYA) Many users are currently located behind NAT NATs which prohibit the usage of proto-41 IPv6 in IPv4 tunnels [RFC3056] unless they manually reconfigure their NAT setup which in some cases is impossible as the NAT cannot be configured to forward proto-41 [RFC1933] to... Hamachi is a zero-configuration virtual private networking (VPN) freeware application. ... In computing, the term stream is used in a number of ways, in all cases referring to a succession of data elements made available over time. ...

• TLS
• SSH

Secure Sockets Layer (SSL) and Transport Layer Security (TLS), its successor, are cryptographic protocols which provide secure communications on the Internet. ... In computing, Secure shell, or SSH, is both a computer program and an associated network protocol designed for logging into and executing commands on a remote computer. ...

References

Tunnelbroker The Free On-line Dictionary of Computing (FOLDOC) is an on-line, searchable encyclopedic dictionary of computing subjects. ... GNU logo The GNU Free Documentation License (GNU FDL or simply GFDL) is a copyleft license for free content, designed by the Free Software Foundation (FSF) for the GNU project. ... See: Tunnel Broker ...