View source for TUN/TAP

{{Short description|Kernel virtual network devices}}
{{about|the network tunnel driver|the software unit testing protocol known as TAP|Test Anything Protocol}}
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{{More citations needed|date=January 2009}}
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In [[computer network]]ing, '''TUN''' and '''TAP''' are [[kernel (operating system)|kernel]] [[Network virtualization|virtual network]] devices. Being network devices supported entirely in software, they differ from ordinary network devices which are backed by physical [[network interface controller|network adapters]].

The '''Universal TUN/TAP Driver''' originated in 2000 as a merger of the corresponding drivers in Solaris, Linux and BSD.<ref>{{cite web
 |url=http://vtun.sourceforge.net/tun/index.html
 |title=Universal TUN/TAP driver
 |website=[[VTun]] project on [[SourceForge]]
 |access-date=2019-07-12 }}
</ref> The driver continues to be maintained as part of the Linux<ref name="tuntap-linux-docs">{{cite web
 |url=https://www.kernel.org/doc/Documentation/networking/tuntap.txt
 |title=Universal TUN/TAP device driver
 |website=[[Linux kernel]]
 |access-date=2020-08-17}}
</ref> and FreeBSD<ref>{{cite web
 |url=https://www.freebsd.org/cgi/man.cgi?query=tun
 |title=TUN(4) manual page
 |website=[[FreeBSD]]
 |access-date=2019-07-12 }}
</ref><ref>{{cite web
 |url=https://www.freebsd.org/cgi/man.cgi?query=tap&sektion=4
 |title=TAP(4) manual page
 |website=[[FreeBSD]]
 |access-date=2019-07-12 }}
</ref><ref>{{cite news |title=VPNs to bypass Internet Censorship in Saudi Arabia |url=https://vpnquery.com/best-vpn-for-saudi-arabia-check-top-5/ |access-date=12 June 2019}}</ref> kernels.

== Design ==
[[File:Tun-tap-osilayers-diagram.png|thumb|upright=1.8|TUN and TAP in the network stack]]

Though both are for tunneling purposes, TUN and TAP cannot be used together because they transmit and receive packets at different layers of the network stack. TUN, namely [[tunneling protocol|network TUNnel]], simulates a [[network layer]] device and operates in [[OSI model#Layer 3: Network layer|layer 3]] carrying [[Internet Protocol|IP]] packets. TAP, namely [[Network tap|network TAP]], simulates a [[link layer]] device and operates in [[OSI model#Layer 2: Data link layer|layer 2]] carrying [[Ethernet]] frames. TUN is used with [[routing]]. TAP can be used to create a [[user space]] [[network bridge]].<ref name="tuntap-linux-docs"/>

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.<ref name="tuntap-linux-docs"/>

== Applications ==

'''[[Virtual private network]]s'''
* [[OpenVPN]], [[Ethernet]]/IP over [[Transmission Control Protocol|TCP]]/[[User Datagram Protocol|UDP]]; encrypted, compressed
* [[ZeroTier]], [[Ethernet]]/IP over [[Transmission Control Protocol|TCP]]/[[User Datagram Protocol|UDP]]; encrypted, compressed, cryptographic addressing scheme
* [[FreeLAN]], open-source, free, multi-platform IPv4, IPv6 and peer-to-peer VPN software over [[User Datagram Protocol|UDP]]/[[Internet Protocol|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 (protocol)|Tinc]], Ethernet/IPv4/[[IPv6]] over TCP/UDP; encrypted, compressed
* [[VTun]], Ethernet/IP/serial/[[Pipeline (Unix)|Unix pipe]] over TCP; encrypted, compressed, traffic-shaping
* [[OpenSSH]]
* [[Cooperative Linux|coLinux]], [[Ethernet]]/IP over [[Transmission Control Protocol|TCP]]/[[User Datagram Protocol|UDP]]
* [[LogMeIn Hamachi|Hamachi]]
* [[OpenConnect]]
* [[WireGuard]]
* [[Tailscale]]
'''Virtual-machine networking'''
* [[Bochs]]
* [[Cooperative Linux|coLinux]]
* [[Hercules (emulator)|Hercules (S/390 emulator)]]
* [[Open vSwitch]]
* [[QEMU]]/[[Kernel-based Virtual Machine|KVM]]
* [[User-mode Linux]]
* [[VirtualBox]]
'''Connecting real machines with [[network simulation]]'''
* [[ns (simulator)|ns-3]]<ref>{{cite web|url=https://www.nsnam.org/docs/doxygen/classns3_1_1_tap_bridge.html |title=ns3::TapBridge Class Reference |publisher=nsnam.org |accessdate=2019-03-28}}</ref>
* [[GNU Radio]]<ref>{{cite web
 |url=https://wiki.gnuradio.org/index.php/TUNTAP_PDU
 |title= TUNTAP PDU
 |accessdate=2023-02-08}}
</ref>
'''NAT'''
* [http://www.litech.org/tayga/ 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'''))<ref>[[Back to My Mac]] uses an [[IPv6]] tunnel on device utun0.</ref>
* [[NetBSD]]
* [[OpenBSD]]
* [[Android (operating system)|Android]]<ref>{{cite web
| url=https://f-droid.org/wiki/page/de.schaeuffelhut.android.openvpn
| title=de.schaeuffelhut.android.openvpn
| publisher=[[F-Droid]]
| date=2013-01-10
| accessdate=2019-03-28}}</ref>
* [[Solaris (operating system)|Solaris]]
* [[Microsoft Windows|Windows]] 2000/XP/Vista/7/8/8.1/10
* [[QNX]]

== See also ==
* [[Point-to-point (telecommunications)]]
* [[MacVTap]]

== References ==
{{Reflist}}

== External links ==
* [https://backreference.org/2010/03/26/tuntap-interface-tutorial/ Tun/Tap interface tutorial]
* [http://www.pocketnix.org/posts/Linux%20Networking:%20MAC%20VLANs%20and%20Virtual%20Ethernets Linux Networking: MAC VLANs and Virtual Ethernets]

{{VPN}}

[[Category:Internet Protocol based network software]]
[[Category:Virtual private networks]]
[[Category:Linux drivers]]
[[Category:Free system software]]


{{Network-software-stub}}