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Creation-Date: 2011-05-19T22:19:04+08:00

====== TUN&TAP ======
Created Thursday 19 May 2011
http://en.wikipedia.org/wiki/TUN/TAP
From Wikipedia, the free encyclopedia

In computer networking, TUN and TAP are virtual network kernel devices. They are network devices that are supported entirely in software, which is different from ordinary network devices that are backed up by hardware network adapters.

TAP (as in network tap) simulates an Ethernet device and it operates with layer 2 packets such as Ethernet frames. TUN (as in network TUNnel) simulates a network layer device and it operates with layer 3 packets such as IP packets. TAP is used to create a network bridge, while TUN is used with routing.

Packets sent by an operating system via a TUN/TAP device are delivered to a user-space program that attaches itself to the device. A user-space program may also pass packets into a TUN/TAP device. In this case TUN/TAP device delivers (or "injects") these packets to the operating system network stack thus emulating their reception from an external source.

TUN/TAP is used for:

    virtual private networks
        OpenVPN, Ethernet/IP over TCP/UDP; encrypted, compressed
        tinc (protocol) [1], Ethernet/IPv4/IPv6 over TCP/UDP; encrypted, compressed
        VTun [2], Ethernet/IP/serial/Unix pipe over TCP; encrypted, compressed, traffic shaping
        OpenSSH
        ICMPTX [3], IP over ICMP (ping)
        NSTX [4], iodine [5], IP over DNS
        HTun [6], IP over HTTP
        coLinux, Ethernet/IP over TCP/UDP
        Hamachi
        NeoRouter
        VPN-X Java TAP Wrapper, VPN-X can be a P2P VPN, can be a SSL VPN
    virtual machine networking
        Bochs
        coLinux
        Hercules (S/390 emulator)
        QEMU/Kvm
        User-mode Linux
        VirtualBox

TUN/TAP drivers are available on at least the following platforms:

    FreeBSD
    Linux, starting around version 2.1.60
    Mac OS X
    NetBSD
    OpenBSD
    Solaris Operating System
    Microsoft Windows 2000/XP/Vista
    QNX, only tap driver

[edit] External links

    http://vtun.sourceforge.net/
    http://www.kernel.org/pub/linux/kernel/people/marcelo/linux-2.4/Documentation/networking/tuntap.txt
    http://tuntaposx.sourceforge.net/ - tun/tap driver for Mac OS X
    http://www.whiteboard.ne.jp/~admin2/tuntap/ - modified tun driver with tap support for Solaris
    http://backreference.org/2010/03/26/tuntap-interface-tutorial/ Tun/Tap Tutorial