TUN/TAP

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

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]^[5] kernels.

Design

TUN and TAP in the network stack

Though both are for tunneling purposes, TUN and TAP can't be used together because they transmit and receive packets at 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, simulates a link layer device and operates in layer 2 carrying Ethernet frames. TUN is used with routing. TAP can be used to create a user space 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

OpenVPN, Ethernet/IP over TCP/UDP; encrypted, compressed
ZeroTier, Ethernet/IP over TCP/UDP; encrypted, compressed, cryptographic addressing scheme
FreeLAN, open-source, free, multi-platform IPv4, IPv6 and peer-to-peer VPN software over UDP/IP.
n2n, an open source Layer 2 over Layer 3 VPN application which uses a peer-to-peer architecture for network membership and routing
Tinc, Ethernet/IPv4/IPv6 over TCP/UDP; encrypted, compressed
VTun, Ethernet/IP/serial/Unix pipe over TCP; encrypted, compressed, traffic-shaping
OpenSSH
coLinux, Ethernet/IP over TCP/UDP
Hamachi
OpenConnect
WireGuard
Tailscale

Virtual-machine networking

Connecting real machines with network simulation

ns-3^[6]
GNU Radio^[7]

NAT

TAYGA, a stateless NAT64 implementation for Linux

Platforms

Platforms with TUN/TAP drivers include:

FreeBSD
Linux, starting around version 2.1.60 of the Linux kernel mainline
iOS (tun driver only)
macOS (native support only for TUN (utun))^[8]
NetBSD
OpenBSD
Android^[9]
Solaris
Windows 2000/XP/Vista/7/8/8.1/10
QNX

References

^ "Universal TUN/TAP driver". VTun project on SourceForge. Retrieved 2019-07-12.
^ ^a ^b ^c "Universal TUN/TAP device driver". Linux kernel. Retrieved 2020-08-17.
^ "TUN(4) manual page". FreeBSD. Retrieved 2019-07-12.
^ "TAP(4) manual page". FreeBSD. Retrieved 2019-07-12.
^ "VPNs to bypass Internet Censorship in Saudi Arabia". Retrieved 12 June 2019.
^ "ns3::TapBridge Class Reference". nsnam.org. Retrieved 2019-03-28.
^ "TUNTAP PDU". Retrieved 2023-02-08.
^ Back to My Mac uses an IPv6 tunnel on device utun0.
^ "de.schaeuffelhut.android.openvpn". F-Droid. 2013-01-10. Retrieved 2019-03-28.

External links

This network-related software article is a stub. You can help Wikipedia by expanding it.

[1] "Universal TUN/TAP driver". VTun project on SourceForge. Retrieved 2019-07-12.

[tuntap-linux-docs-2] "Universal TUN/TAP device driver". Linux kernel. Retrieved 2020-08-17.

[3] "TUN(4) manual page". FreeBSD. Retrieved 2019-07-12.

[4] "TAP(4) manual page". FreeBSD. Retrieved 2019-07-12.

[5] "VPNs to bypass Internet Censorship in Saudi Arabia". Retrieved 12 June 2019.

[6] "ns3::TapBridge Class Reference". nsnam.org. Retrieved 2019-03-28.

[7] "TUNTAP PDU". Retrieved 2023-02-08.

[8] Back to My Mac uses an IPv6 tunnel on device utun0.

[9] "de.schaeuffelhut.android.openvpn". F-Droid. 2013-01-10. Retrieved 2019-03-28.

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