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【速搜问答】MAC地址是什么

问答 admin 1年前 (2020-09-05) 267次浏览 已收录 0个评论

汉英对照:
Chinese-English Translation:

MAC地址也叫物理地址、硬件地址,由网络设备制造商生产时烧录在网卡的EPROM(一种闪存芯片,通常可以通过程序擦写)。IP地址与MAC地址在计算机里都是以二进制表示的,IP地址是32位的,而MAC地址则是48位的。

MAC address, also known as physical address and hardware address, is burned into EPROM of network card (a kind of flash memory chip, which can be erased by program) when it is produced by network equipment manufacturer. IP address and MAC address in the computer are represented in binary, IP address is 32-bit, and MAC address is 48 bit.

MAC 地址(英语:Media Access Control Address),直译为媒体存取控制位址,也称为局域网地址(LAN Address),MAC 位址,以太网地址(Ethernet Address)或物理地址(Physical Address),它是一个用来确认网络设备位置的位址。在 OSI 模型中,第三层网络层负责 IP 地址,第二层数据链路层则负责 MAC 位址。MAC 地址用于在网络中唯一标示一个网卡,一台设备若有一或多个网卡,则每个网卡都需要并会有一个唯一的 MAC 地址。

MAC address (English: media access control address), literal translation of media access control address, also known as LAN address, MAC address, Ethernet address or physical address, it is an address used to confirm the location of network equipment. In OSI model, the third layer of network layer is responsible for IP address, and the second layer of data link layer is responsible for MAC address. MAC address is used to uniquely identify a network card in the network. If a device has one or more network cards, each network card needs and will have a unique MAC address.

MAC 地址也叫物理地址、硬件地址,由网络设备制造商生产时烧录在网卡(Network lnterface Card)的 EPROM(一种闪存芯片,通常可以通过程序擦写)。IP 地址与 MAC 地址在计算机里都是以二进制表示的,IP 地址是 32 位的,而 MAC 地址则是 48 位的。

MAC address is also called physical address and hardware address. It is produced by network equipment manufacturer and recorded in EPROM of network interface card (a kind of flash memory chip, which can be erased by program). IP address and MAC address in the computer are represented in binary, IP address is 32-bit, and MAC address is 48 bit.

MAC 地址的长度为 48 位(6 个字节),通常表示为 12 个 16 进制数,如:00-16-EA-AE-3C-40 就是一个 MAC 地址,其中前 6 位 16 进制数 00-16-EA 代表网络硬件制造商的编号,它由 IEEE(电气与电子工程师协会)分配,而后 6 位 16 进制数 AE-3C-40 代表该制造商所制造的某个网络产品(如网卡)的系列号。只要不更改自己的 MAC 地址,MAC 地址在世界是唯一的。形象地说,MAC 地址就如同身份证上的身份证号码,具有唯一性。

The length of MAC address is 48 bits (6 bytes), which is usually expressed as 12 hexadecimal numbers. For example, 00-16-ea-ae-3c-40 is a MAC address. The first six hexadecimal numbers 00-16-ea represent the network hardware manufacturer’s number, which is assigned by IEEE (Institute of electrical and Electronic Engineers), and the last six hexadecimal numbers ae-3c-40 Represents the serial number of a network product (such as a network card) manufactured by the manufacturer. As long as you don’t change your Mac address, MAC address is unique in the world. Figuratively speaking, the MAC address is just like the ID card number on the ID card, with uniqueness.

结构

structure

网络中每台设备都有一个唯一的网络标识,这个地址叫 MAC 地址或网卡地址,由网络设备制造商生产时写在硬件内部。MAC 地址则是 48 位的(6 个字节),通常表示为 12 个 16 进制数,每 2 个 16 进制数之间用冒号隔开,如 08:00:20:0A:8C:6D 就是一个 MAC 地址。具体如下图所示,其前 3 字节表示 OUI(Organizationally Unique Identifier),是 IEEE 的注册管理机构给不同厂家分配的代码,区分不同的厂家。后 3 字节由厂家自行分配。

Each device in the network has a unique network identification, which is called MAC address or network card address. It is written in the hardware when the network equipment manufacturer produces it. MAC address is 48 bits (6 bytes), which is usually expressed as 12 hexadecimal numbers. Each two hexadecimal numbers are separated by colons. For example, 08:00:20:0a: 8C: 6D is a MAC address. As shown in the figure below, the first three bytes indicate oui (organizationally unique identifier), which is the code assigned to different manufacturers by the registration management organization of IEEE to distinguish different manufacturers. The last 3 bytes are allocated by the manufacturer.

MAC 地址最高字节(MSB)的低第二位(LSb)表示这个 MAC 地址是全局的还是本地的,即 U/L(Universal/Local)位,如果为 0,表示是全局地址。所有的 OUI 这一位都是 0。

The lower second bit (LSB) of the highest byte (MSB) of MAC address indicates whether the MAC address is global or local, that is, U / L (Universal / local) bit. If it is 0, it means global address. All oui bits are 0.

MAC 地址最高字节(MSB)的低第一位(LSb),表示这个 MAC 地址是单播还是多播。0 表示单播。

The lower first bit (LSB) of the highest byte (MSB) of the MAC address indicates whether the MAC address is unicast or multicast. 0 means unicast.

工作过程

working process

网络上的数据包从初始点开始 ,经过一个个中间节点最终到达目标节点 ,数据包是如何从初始节点开始识别一个个中间节点最终找到目标节点的呢? 实际上初始节点是根据目标节点的地址 ,将目标节点的 IP 地址映射到中间节点的 MAC 地址,找到第一个中间节点。从第一个中间节点出发,根据目标节点的 IP 地址映射到第二个中间节点的 MAC 地址,从而找到第二个中间节点……,以此类推,直到当找到最后一个中间节点后,从最后一个中间节点出发,根据目标节点的地址映射到目的节点的 MAC 地址,从而将数据包传送给目标主机。所以数据包的传送过程就是:不断地将目标节点的地址映射到一个个中间节点的 MAC 地址,再从一个个中间节点出发,直到找到最终的目标节点。

The data packet on the network starts from the initial point, passes through the intermediate nodes and finally reaches the target node. How does the data packet identify each intermediate node from the initial node and finally find the target node? In fact, the initial node maps the IP address of the target node to the MAC address of the intermediate node according to the address of the target node to find the first intermediate node. Starting from the first intermediate node, the IP address of the target node is mapped to the MAC address of the second intermediate node to find the second intermediate node And so on, until the last intermediate node is found, starting from the last intermediate node, mapping the destination node’s MAC address according to the target node’s address, so as to transmit the data packet to the target host. So the process of data packet transmission is: constantly mapping the address of the target node to the MAC address of each intermediate node, and then starting from each intermediate node until the final target node is found.

数据包传送的关键是将目标节点的 IP 地址映射到中间节点的 MAC 地址。IP 地址与 MAC 地址的映射要通过 ARP 地址解析协议来完成,它可将网络中的 IP 地址映射到主机的 MAC 地址,如交换机可以根据网络中的 IP 地址来找到本地主机的 MAC 地址。具体过程是:当交换机接收到来自网上一个数据包时,会根据该数据包的目标 IP 地址,查看交换机内部是否有跟该 IP 地址对应的 MAC 地址 ,如果有上次保留下来的对应的 MAC 地址,就会将该数据包 转发到对应 MAC 地址的主机上去。如果在交换机内部没有与目标)地址对应的 MAC 地址,则交换机会根据 ARP 协议将目标 IP 地址按照“表”中的对应关系映射成 MAC 地址 ,数据包就被转送到对应的 MAC 地址的主机上。

The key of packet transmission is to map the IP address of the target node to the MAC address of the intermediate node. The mapping between IP address and MAC address is accomplished by ARP address resolution protocol, which can map IP address in network to MAC address of host. For example, switch can find MAC address of local host according to IP address in network. The specific process is: when the switch receives a packet from the network, it will check whether there is a MAC address corresponding to the IP address in the switch according to the destination IP address of the packet. If there is the corresponding MAC address reserved last time, the packet will be transferred to the host with the corresponding MAC address. If there is no MAC address corresponding to the target address in the switch, the switch will map the target IP address into the MAC address according to the corresponding relationship in the “table” according to the ARP protocol, and the data packet will be transferred to the host with the corresponding MAC address.

作用

effect

IP 地址是基于逻辑的,比较灵活,不受硬件的限制,也容易记忆。而 MAC 地址在一定程度上与硬件一致,是基于物理的,能够标识具体的网络节点。这两种地址各有优点,使用时也因条件不同而采取不同的地址。

IP address is based on logic, more flexible, not limited by hardware, but also easy to remember. The MAC address is consistent with the hardware to a certain extent. It is based on the physical and can identify the specific network node. These two kinds of addresses have their own advantages, and different addresses are adopted due to different conditions.

大多数接入 Internet 的方式是把主机通过局域网组织在一起,然后再通过交换机或路由器等设备和 Internet 相连接。这样一来就出现了如何区分具体用户,防止 IP 地址被盗用的问题。由于 IP 地址只是逻辑上的标识,任何人都能随意修改,因此不能用来具体标识一个用户。而 MAC 地址则不然,它是固化在网卡里面的。从理论上讲,除非盗来硬件即网卡,否则一般是不能被冒名顶替的。基于 MAC 地址的这种特点,因此局域网采用了用 MAC 地址来标识具体用户的方法。

Most of the ways to access the Internet are to organize the hosts together through LAN, and then connect to the Internet through switches or routers. In this way, how to distinguish specific users and prevent IP address from being stolen. Because IP address is only a logical identification, anyone can modify it at will, so it can’t be used to identify a user. But MAC address is not, it is solidified in the network card. Theoretically speaking, unless the hardware is stolen, that is, the network card, it can not be replaced by an impostor. Based on this characteristic of MAC address, LAN uses MAC address to identify specific users.

在具体的通信过程中,通过交换机内部的交换表把 MAC 地址和 IP 地址一一对应。当有发送给本地局域网内一台主机的数据包时,交换机首先将数据包接收下来,然后把数据包中的 IP 地址按照交换表中的对应关系映射成 MAC 地址,然后将数据包转发到对应的 MAC 地址的主机上去。这样一来,即使某台主机盗用了这个 IP 地址,但由于此主机没有对应的 MAC 地址,因此也不能收到数据包,发送过程和接收过程类似。

In the specific communication process, the MAC address and IP address are corresponding one by one through the exchange table inside the switch. When there is a packet sent to a host in the local area network, the switch first receives the packet, then maps the IP address in the packet into the MAC address according to the corresponding relationship in the exchange table, and then forwards the packet to the host with the corresponding MAC address. In this way, even if a host steals the IP address, it cannot receive packets because it has no corresponding MAC address. The sending process is similar to the receiving process.

所以,无论是局域网,还是广域网中的计算机之间进行通信时,最终都表现为将数据包从某种形式的链路上的一个初始节点出发,从一个节点传递到另一个节点,最终传送到目的节点。数据包在这些节点之间的传递都是由 ARP(Address Resolution Protocol:地址解析协议)负责将 IP 地址映射到 MAC 地址上来完成的。

Therefore, whether it is LAN or WAN computer communication, the final performance is to start from an initial node on a certain form of link, from one node to another node, and finally to the destination node. ARP (address resolution protocol) is responsible for mapping IP address to MAC address.

身份证就是用来证明一个人的身份。平日身份证的作用并不是很大,但是到了有的关键时刻,必须有身份证来说明一个人的一切。那么,IP 地址与 MAC 地址绑定,就如同在日常生活中一个人与身份证的关系。因为,IP 地址可以随意的,但 MAC 地址是唯一说明 IP 地址身份的。例如,为防止 IP 地址被盗用,通常交换机的端口绑定(端口的 MAC 表使用静态表项),可以在每个交换机端口只连接一台主机的情况下防止修改 MAC 地址的盗用,如果是三层设备还可以提供交换机端口、IP 地址和 MAC 地址三者的绑定。

ID card is used to prove a person’s identity. On weekdays, the role of ID card is not very big, but at some critical moment, it is necessary to have an ID card to explain everything of a person. Then, the binding of IP address and MAC address is just like the relationship between a person and ID card in daily life. Because, the IP address can be arbitrary, but MAC address is the only IP address to indicate the identity. For example, in order to prevent the IP address from being embezzled, the port binding of the switch (Port MAC table uses static table entry) can prevent the modification of MAC address embezzlement when each switch port is connected to only one host. If it is a layer-3 device, it can also provide the binding of switch port, IP address and MAC address.

获取方法

Acquisition method

在命令提示符下输入命令“ipconfig /all”回车之后就会显示当前计算机的一些网络信息,其中“Physical Address”字样的这一项就是当前计算机中网卡的 MAC 地址。当然,如果计算机中安装有多个网卡,则会有多个“Physical Address”字样。

After entering the command “ipconfig / all” at the command prompt, some network information of the current computer will be displayed, in which the item of “physical address” is the MAC address of the network card in the current computer. Of course, if there are multiple network cards installed in the computer, there will be multiple “physical address” words.


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