MAC address

MAC address


Media Access Control address (MAC or sometimes called ethernet address) is a unique identifier assigned to network interfaces for communications on the physical network segment. Logically, MAC addresses are used in the Media Access Control protocol sub-layer of the OSI reference model.

MAC addresses are most often assigned by the manufacturer of a network interface card (NIC) and are stored in its hardware, the card's read-only memory, or some other firmware mechanism. If assigned by the manufacturer, a MAC address usually encodes the manufacturer's registered identification number. It may also be known as an Ethernet hardware address (EHA), hardware address, adapter address, or physical address.

MAC addresses are formed according to the rules of one of three numbering name spaces managed by the Institute of Electrical and Electronics Engineers (IEEE): MAC-48, EUI-48, and EUI-64. The IEEE claims trademarks on the names EUI-48 and EUI-64, in which EUI is an acronym for Extended Unique Identifier.

Although intended to be a permanent and globally unique identification, it is possible to change the MAC address on most of today's hardware, an action often referred to as MAC spoofing. Unlike IP address spoofing, where senders spoofing their address in a request direct the receiver into sending the response elsewhere, in MAC address spoofing, the response is received by the spoofing party. However, MAC address spoofing is limited to the local broadcast domain.

A host cannot determine from the MAC address of another host whether that host is on the same link (network segment) as the sending host, or on a network segment bridged to that network segment.

In TCP/IP networks, the MAC address of an interface can be queried knowing the IP address using the Address Resolution Protocol (ARP) for Internet Protocol Version 4 (IPv4) or the Neighbor Discovery Protocol (NDP) for IPv6. On broadcast networks, such as Ethernet, the MAC address uniquely identifies each node on that segment and allows frames to be marked for specific hosts. It thus forms the basis of most of the Link layer (OSI Layer 2) networking upon which upper layer protocols rely to produce complex, functioning networks.

Address Resolution Protocol[]

arp command sends a broadcast to find all MAC hardware on the LAN. For windows the command is arp -a and for Linux the command is arp.





How To Check MAC Address In Windows XP

How To Check MAC Address In Windows XP