Tunneling protocol
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| The five layer TCP/IP model |
| 5. Application layer |
|
DHCP • DNS • FTP • HTTP • IMAP4 • IRC • NNTP • XMPP • MIME • POP3 • SIP • SMTP • SNMP • SSH • TELNET • BGP • RPC • RTP • RTCP • TLS/SSL • SDP • SOAP • L2TP • PPTP • … |
| 4. Transport layer |
| 3. Network layer |
| 2. Data link layer |
|
ATM • DTM • Ethernet • FDDI • Frame Relay • GPRS • PPP • ARP • RARP • … |
| 1. Physical layer |
|
Ethernet physical layer • ISDN • Modems • PLC • SONET/SDH • G.709 • Wi-Fi • … |
A tunneling protocol is a network protocol which encapsulates one protocol or session inside a higher layer protocol or a protocol at the same layer. Tunneling may be used to transport a data link layer protocol over a transport layer protocol, as if it were a higher layer protocol. Tunneling may be used to provide various types of VPN functionality such as private addressing.
Examples of tunneling protocols include:
Datagram-based:
- 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 TCP)
- 6to4 (IPv6 over IPv4 as protocol 41)
- Teredo (IPv6 over UDP over IPv4)
- Anything In Anything (AYIYA; e.g. IPv6 over UDP over IPv4, IPv4 over IPv6, IPv6 over TCP IPv4, etc.)
Stream-based:
Contents |
[edit] SSH tunneling
SSH is frequently used to tunnel insecure traffic over the Internet in a secure way. For example, Windows machines can share files using the SMB protocol, which is not encrypted. If you were to mount a Windows filesystem remotely through the Internet, someone snooping on the connection could see your files.
So to mount an SMB file system securely, one can establish an SSH tunnel that routes all SMB traffic to the fileserver inside an SSH-encrypted connection. Even though the SMB traffic itself is insecure, because it travels within an encrypted connection it becomes secure.
[edit] Tunneling to bypass firewalls
Tunneling can also be used to bypass a system firewall. In this case, firewall-blocked data is encapsulated inside a commonly allowed protocol such as HTTP. One example of this type of use is HTTP-Tunnel.
[edit] See also
[edit] References
This article was originally based on material from the Free On-line Dictionary of Computing, which is licensed under the GFDL.
