TUN/TAP

In computer networking, TUN and TAP are virtual network kernel interfaces. Being network devices supported entirely in software, they differ from ordinary network devices which are backed up by hardware network adapters.

This article is about the network tunnel driver. For the software unit testing protocol known as TAP, see Test Anything Protocol.

The Universal TUN/TAP Driver originated in 2000 as a merger of the corresponding drivers in Solaris, Linux and BSD.[1] The driver continues to be maintained as part of the Linux[2] and FreeBSD[3][4] kernels.

Design
TUN and TAP in the network stack

Though for similar tunneling purposes, only one at a time can be used because TUN and TAP apply to different layers of the network stack. TUN, namely network TUNnel, simulates a network layer device and operates in layer 3 carrying IP packets. TAP, namely network TAP (Terminal Access Point), simulates a link layer device and operates in layer 2 carrying Ethernet frames. TUN is used with routing. TAP is used for creating a network bridge.[2]

Packets sent by an operating system via a TUN/TAP device are delivered to a user-space program which attaches itself to the device. A user-space program may also pass packets into a TUN/TAP device. In this case the TUN/TAP device delivers (or "injects") these packets to the operating-system network stack thus emulating their reception from an external source.[2]

Applications
Virtual private networks
Virtual-machine networking
Connecting real machines with network simulation
NAT

Platforms

Platforms with TUN/TAP drivers include:

See also

References
  1. "Universal TUN/TAP driver". VTun project on SourceForge. Retrieved 2019-07-12.
  2. "Universal TUN/TAP device driver". GitHub mirror of Linux kernel. Retrieved 2019-07-12.
  3. "TUN(4) manual page". FreeBSD. Retrieved 2019-07-12.
  4. "TAP(4) manual page". FreeBSD. Retrieved 2019-07-12.
  5. "ns3::TapBridge Class Reference". nsnam.org. Retrieved 2019-03-28.
  6. Back to My Mac uses an IPv6 tunnel on device utun0.
  7. "de.schaeuffelhut.android.openvpn". F-Droid. 2013-01-10. Retrieved 2019-03-28.


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