what is linux tap-Linux Operation and Maintenance-php.cn

In Linux, TAP's full name is "Tunneling traffic access point". It is a virtual network card technology used on Linux, which can provide secure network connections for applications. A virtual network can be implemented using the TAP network interface. This virtual network can provide an environment similar to a real network for applications to be tested in the software without establishing actual network conditions.

what is linux tap

#The operating environment of this tutorial: linux7.3 system, Dell G3 computer.

What is linux tap

The detailed explanation of the TAP network interface in Linux is a very important part of Linux network management. It can be used Establish virtual networks, simulate networks, manage network traffic, and implement secure network functions, etc. This article will introduce the basic principles of the TAP network interface, how to use it for network management, the difference from Ethernet, and its more application scenarios.

TAP, Tunneling traffic access point, is a virtual network card technology used on Linux, which can provide secure network connections for applications. The design of TAP is that it is a virtual network card. Like a real Ethernet card, it can be mapped to the network and can then send and receive network data packets. The TAP network interface can be used to establish virtual networks, simulate networks, manage network traffic, and implement secure network functions.

Linux can realize direct data packet transmission between two or even multiple computers through the TAP network interface, and can also achieve network isolation through multiple routers to safely transmit data. Using the TAP network interface, users can not only provide network services to users according to certain rules, but also manage network traffic through control to ensure network security.

Using the TAP network interface, a virtual network can be implemented. This virtual network can provide an environment similar to a real network for applications to be tested in the software without establishing actual network conditions. The TAP network interface also helps manage network traffic, filtering useless data packets from the network, protecting network security, and reducing dependence on network speed and network quality.

Compared with Ethernet technology, TAP technology is more suitable for establishing virtual networks on Linux systems, such as network security, network isolation, and the use of network agents. TAP can also be used in conjunction with Ethernet to utilize dual functions of network resources.

As can be seen from the above introduction, the TAP network interface is widely used in Linux network management. It can be used to establish virtual networks, simulate networks, manage network traffic, and implement secure network functions.

In short, the TAP network interface is a very commonly used network technology on Linux systems. It can not only be used to connect different computers, but also can be used to establish virtual networks to achieve network security and network isolation. Utilize network resources more efficiently.

The difference between tap and tun:

tap is located at the second layer (data link layer) of the network OSI model, and tun is located at the third layer of the network. Here is a brief explanation of tap.

Tap practice on Linux host

If you want to use the Linux command line to operate a tap, first Linux must have the tun module (Linux uses the tun module Implemented tun and tap).

The checking method is as follows:

# 如果使用命令 modinfo tun，有输出的话，就说明具有tun模块
[root@public ~]# modinfo tun
filename:       /lib/modules/3.10.0-693.11.1.el7.x86_64/kernel/drivers/net/tun.ko.xz
alias:          devname:net/tun
alias:          char-major-10-200
license:        GPL
author:         (C) 1999-2004 Max Krasnyansky <maxk@qualcomm.com>
description:    Universal TUN/TAP device driver
rhelversion:    7.4
srcversion:     4E9F57A6269CFD0F4BE4021
depends:
intree:         Y
vermagic:       3.10.0-693.11.1.el7.x86_64 SMP mod_unload modversions
signer:         CentOS Linux kernel signing key
sig_key:        61:B8:E8:7B:84:11:84:F6:2F:80:D6:07:79:AB:69:2A:49:D8:3B:AF
sig_hashalgo:   sha256
[root@public ~]#

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When the Linux version has the tun module, you have to check whether it has been loaded. The checking method is as follows:

# 使用该命令检查后，无回显，表示当前未加载该模块
[root@public ~]# lsmod | grep tun
[root@public ~]#
# 使用该命令加载该模块
[root@public ~]# modprobe tun
[root@public ~]#
[root@public ~]# lsmod | grep tun
tun                    31621  0

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After loading the module, also It is necessary to check whether Linux has a command line tool tunctl for operating tun/tap.

# 可以使用yum直接安装，如果yum源中没有的话，可以去阿里源的网站中下载rpm包然后安装。
[root@public ~]# yum -y install tunctl

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After having the tun module and tunctl, you can create a tap device, command:

[root@public ~]# tunctl -t tap_test
Set &#39;tap_test&#39; persistent and owned by uid 0
[root@public ~]# ip link list
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 1000
    link/ether fa:16:3e:08:0b:39 brd ff:ff:ff:ff:ff:ff
3: tap_test: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT qlen 1000
    link/ether ce:cc:18:91:1e:ba brd ff:ff:ff:ff:ff:ff
[root@public ~]#

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Add IP address:

[root@public ~]# ip addr add local 192.168.10.100/24 dev tap_test
[root@public ~]# ip a s
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether fa:16:3e:08:0b:39 brd ff:ff:ff:ff:ff:ff
    inet 192.168.10.93/24 brd 192.168.10.255 scope global noprefixroute dynamic eth0
       valid_lft 75733sec preferred_lft 75733sec
    inet6 fe80::f816:3eff:fe08:b39/64 scope link
       valid_lft forever preferred_lft forever
3: tap_test: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000
    link/ether ce:cc:18:91:1e:ba brd ff:ff:ff:ff:ff:ff
    inet 192.168.10.100/24 scope global tap_test
       valid_lft forever preferred_lft forever
[root@public ~]#

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