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What is the difference between TUN and TAP?
1 Answer. TAP is basically at Ethernet level (layer 2) and acts like a switch where as TUN works at network level (layer 3) and routes packets on the VPN. TAP is bridging whereas TUN is routing.
What is TUN interface in Linux?
Tun/tap interfaces are a feature offered by Linux (and probably by other UNIX-like operating systems) that can do userspace networking, that is, allow userspace programs to see raw network traffic (at the ethernet or IP level) and do whatever they like with it.
What is TAP network interface?
Tap interfaces are special software entities which tell the Linux bridge to forward Ethernet frames as it is. In other words, the virtual machines connected to tap interfaces will be able to receive raw Ethernet frames.
What is tun0 Openvpn?
Your “clear” unencrypted traffic goes to tun0, where openvpn encapsulates and encrypts it, and sends it out of eth0 to the remote gateway, where it is decrypted. So if you block eth0, then you will prevent the encrypted packets being sent to the remote gateway. tun0 provides a routing path.
How to create a tap interface in Tun?
The above command creates a new TAP interface called tap0 and then shows some information about the device. You will probably notice that after creation the tap0 device reports that it is in the down state. This is by design and it will come up only when something binds it (see here). The output of the show command will look something like this:
How to tell if a tap device is tun or tap device?
Basically, it can either take the value IFF_TUN to indicate a TUN device (no ethernet headers in the packets), or IFF_TAP to indicate a TAP device (with ethernet headers in packets). Additionally, another flag IFF_NO_PI can be ORed with the base value. IFF_NO_PI tells the kernel to not provide packet information.
How is TUN / TAP interface used in KVM?
When VM0 sends a packet to its eth0, KVM sends it to TAP interface vnet0 so that the bridge will forward it to vnet1. Then KVM receives it and sends it to VM1’s eth0. ip tuntap can be used to manage TUN/TAP interfaces.
Which is an example of a tun interface?
The typical use case of a TUN interface is IP tunneling. For example, OpenVPN receives packets from a TUN interface such as tun0 and encrypts it before sending to the real ethernet interface eth0 . Then the OpenVPN client on the peer receives the packet from eth0 and decrypts it before sending it to tun0.