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. The driver continues to be maintained as part of the Linux and FreeBSD kernels.
Design
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 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.
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.
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 Bochs coLinux Hercules (S/390 emulator) Open vSwitch QEMU/KVM User-mode Linux VirtualBox Connecting real machines with network simulation ns-3 GNU Radio 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))Back to My Mac uses an IPv6 tunnel on device utun0. NetBSD OpenBSD Android Solaris Windows 2000/XP/Vista/7/8/8.1/10 QNX
See also Point-to-point (telecommunications) MacVTap
References
External links Tun/Tap interface tutorial Linux Networking: MAC VLANs and Virtual Ethernets