What's the Chinese name of MAC?

Measurement and Control (measurement and control)

Media access control

Media access control

Media access control sublayer protocol

It defines the transmission mode of data packets on the medium. In a link sharing the same bandwidth, access to the connection medium is "first come, first served". Physical addressing is defined here, as well as logical topology (the path of signals through the physical topology). Line control, error notification (uncorrected), frame transmission sequence and optional flow control are also implemented in this sublayer.

Note: This protocol is located in the lower half of the data link layer of OSI seven-layer protocol, and is mainly responsible for controlling and connecting the physical media of the physical layer. When sending data, MAC protocol can judge whether the data can be sent in advance. If it can be sent, it will add some control information to the data and finally send the data and control information to the physical layer in a specified format. When receiving data, MAC protocol first judges whether there is transmission error in the input information. If there is no error, it removes the control information and sends it to LLC layer.

Application: MAC protocol is widely used in both traditional wired local area network (LAN) and popular wireless local area network (WLAN). In the traditional LAN, the physical layer of various transmission media corresponds to the corresponding MAC layer. At present, the commonly used network adopts the MAC layer standard of IEEE 802.3 and adopts CSMA/CD access control mode. In WLAN, the standard of MAC is IEEE 802. 1 1, and the working mode adopts DCF (distributed control) and PCF (central control).

McIntosh raincoat

Original English meaning: Macintosh

English explanation: Macintosh computer

Chinese mainland once used the translated name "Macintosh", but it has been rare recently. The Macintosh Users Association in Chinese mainland also changed the computer name to "Macintosh". Mainland residents sometimes call Macintosh "Mac".

Membrane attack complex

Immunology refers to the membrane attack complex produced after complement activation.

MAC: In the hygienic standard, it refers to the maximum allowable concentration.

MAC has always been used in the formulation of health standards.

The concept of MAC refers to the upper limit that should not be exceeded in many representative tests.

It is the value that harmful substances in the air of workers' workplaces must not exceed the standard.

Matching detection method adopts fixed-point sampling method to measure instantaneous concentration (such as syringe, gas sampling tube or gas detection tube, etc.). ) or short-term average concentration, and most tests belong to the latter.

Mac operating system

Mac system is a dedicated MAC system, and it can't be installed on ordinary pc in general.

Apple not only produces most of the hardware of MAC, but also develops its own operating system. Next, let's look at its operating system.

MAC's current operating system has reached OS 10, and its code name is MAC OS X (the Roman numeral for x is 10), which is the biggest change since the birth of MAC computer 15. The new system is very reliable, and many of its functions and services reflect Apple's philosophy.

In addition, the computer viruses that are raging now are almost all aimed at Windows. Because the architecture of MAC is different from that of Windows, it is rarely attacked by viruses. The interface of MAC OSX operating system is very unique, which highlights vivid icons and man-machine dialogue (man-machine dialogue interface was first created by Apple, and was later favored by Microsoft Windows and widely used in Windows). Apple can produce computers according to its own technical standards and independently develop the corresponding operating system, which shows that its technology and strength are extraordinary. For example, Apple, like a combination of Dell and Microsoft, is "both talented and beautiful" in software and hardware.

mac address

MAC (Media Access Control) MAC address is a MAC address burned in a network interface card (NIC), also known as a hardware address. It consists of 48 bits (6 bytes) and 16 bits. 0-23 digits are assigned by the manufacturer, which is called organization unique. The 40th bit is the multicast address flag bit. The physical address of the network card is usually the EPROM (a flash memory chip that can be erased by program) burned into the network card by the network card manufacturer, which stores the address that truly identifies the computer that sent the data and the host that received the data when transmitting the data.

In other words, in the process of physical transmission at the bottom of the network, the host is identified by its physical address, which is generally unique in the world. For example, the physical address of a famous Ethernet card is a 48-bit integer, such as 44-45-53-54-00-00, which is stored in the host interface in a machine-readable manner. Ethernet Address Management Organization (IEEE) divides Ethernet addresses, that is, different combinations of 48 bits, into several independent and continuous address groups, and the manufacturer of Ethernet cards buys one of them, and gives the Ethernet cards unique addresses one by one during the specific production.

Vividly speaking, the MAC address is just like the ID number on our ID card, which is unique in the world.

How to get the MAC of this machine?

For a few machines, we can get the MAC address as follows: In Windows 98/Me, click Start → Run → Enter winipcfg"→ Enter. You can see the MAC address.

In Windows 2000/XP, click Start → Run → Enter CMD"→ Enter → Enter ipconfig /all"→ Enter. You can see the MAC address.

Method of modifying MAC address of network card

In fact, the function of changing the MAC address of the network card, whether it is 98, 2000 or XP, has been provided, but everyone usually doesn't notice it. Let me tell you how to change it. It's simple. . .

Ok, now let's look at WIN2000. Right-click the icon of My Network Places on the desktop, and then select Properties. There are generally two icons in the Network and Dial-up Connections window, one is the New Connection icon, and the other is the My Connection icon. If you have two network cards on your machine, there are three icons. If you only have a network card, right-click the My Connection icon and select Properties to open the My Connection Properties window. At the top of the diagram, there is a sign "Use when connecting". This is the model of the network card on your machine. There is a "Configure" button below. Click this button to enter the network card properties dialog box. There are five property pages in this dialog box. Click the second "Advanced" page, and there are two items under the "Properties" label: one is "Link speed/duplex mode", which is to set the working speed of the network card. What we need to change is the following "network address". Click this item. There are two radio options under the "Value" logo on the right side of the dialog box, and the default value is "Does not exist". We just need to select the radio above, then enter the MAC address of the network card you want to change in the box on the right, and click OK. After a while, the network card address will be changed, and you don't even have to stop using the network card!

In addition, you can also open the property page of the network card in "Settings Manager" to modify it, and the effect is the same. WINXP is modified in the same way as WIN2000.

The modification under 98 is similar to that under WIN2000 and XP. Right-click the Network Places icon and select Properties to open the Network dialog box. In the Configuration box, double-click the network card you want to modify to open the network card properties dialog box. In the "Advanced" option, click the "Network Address" item under the "Properties" label, select one of the two items on the right, and then enter the MAC address of the network card you want to modify in the box. After clicking OK, you will be prompted to restart. After restarting, your network card address will be successfully modified! !

If you want to restore the MAC address of the network card to its original state, just select the radio on the right side of the "network address" item as "Don't show" below and restart. Under WIN2000 and XP, you can choose "does not exist", and of course you don't need to restart.

Message authentication code

Message authentication code is also called encrypted checksum.

A discriminant function.

The principle of message authentication code is to use public functions and keys to generate a fixed-length value as an authentication identifier, and use this identifier to authenticate the integrity of the message. A small data block with a fixed size, that is, a MAC, is generated by using a key, which is added to a message and then sent. The receiver uses the key shared with the sender for authentication.

MAC: maximum allowable concentration,

The concentration of toxic chemicals should not be exceeded in the workplace, within one working day and at any time.

Mandatory access control

Mandatory access control.

Mandatory access control allows new access control modules to be loaded, thus realizing new security policies, some of which provide protection for very small system subsets and strengthen specific services, while others provide comprehensive label security protection for all subjects and objects. The mandatory part of the definition stems from the fact that control is carried out by administrators and systems, unlike autonomous access control (DAC, standard files in FreeBSD and System V IPC permissions) which is carried out according to users' wishes.

Mandatory access control is an access control implemented by the system independently of the user's behavior, and it also provides the control enjoyed by the objects (data objects) among the subjects (database users). However, the mandatory access control mechanism determines whether to grant or deny users access to resources by comparing the security levels of subjects and objects, thus preventing illegal and unauthorized access to information and ensuring the confidentiality of information. Different from discretionary access control, mandatory access control is managed by security administrators, who set it according to certain rules. Ordinary database users cannot change their security level or the security attributes of objects. Although discretionary access control is also a part of system security policy, it is mainly managed by the owner of the object.

MAC is sometimes used to address people who don't know their names. In scientific terms, it means the maximum air concentration. The abbreviation of Military Airborne Command is also MAC.