A MAC address, sometimes referred to as a hardware address or physical address, is an ID code that’s assigned to a network adapter or any device with built-in networking capability (say, a printer). While an IP address can potentially be assigned to any device, a MAC address is “burned in” to a given device from the factory. Since ethernet uses MAC addresses, the sender needs to get the MAC address of the next hop. There is a special protocol ARP (address resolution protocol) that is used for that. Once the sender has retrieved the MAC address of the next hop, he writes that target MAC address into the packet and sends the packet.
Address Resolution Protocol (ARP) is a procedure for mapping a dynamic Internet Protocol address (IP address) to a permanent physical machine address in a local area network (LAN). Quicken 2017 for mac. The physical machine address is also known as a Media Access Control or MAC address.
The job of the ARP is essentially to translate 32-bit addresses to 48-bit addresses and vice-versa. This is necessary because in IP Version 4 (IPv4), the most common level of Internet Protocol (IP) in use today, an IP address is 32-bits long, but MAC addresses are 48-bits long.
ARP works between network layers 2 and 3 of the Open Systems Interconnection model (OSI model). The MAC address exists on layer 2 of the OSI model, the network layer, while the IP address exists on layer 3, the data link layer.
Recording interface for mac. ARP can also be used for IP over other LAN technologies, such as token ring, fiber distributed data interface (FDDI) and IP over ATM.
In IPv6, which uses 128-bit addresses, ARP has been replaced by the Neighbor Discovery protocol.
How ARP works
When a new computer joins a LAN, it is assigned a unique IP address to use for identification and communication. When an incoming packet destined for a host machine on a particular LAN arrives at a gateway, the gateway asks the ARP program to find a MAC address that matches the IP address. A table called the ARP cache maintains a record of each IP address and its corresponding MAC address.
All operating systems in an IPv4 Ethernet network keep an ARP cache. Every time a host requests a MAC address in order to send a packet to another host in the LAN, it checks its ARP cache to see if the IP to MAC address translation already exists. If it does, then a new ARP request is unnecessary. If the translation does not already exist, then the request for network addresses is sent and ARP is performed.
ARP broadcasts a request packet to all the machines on the LAN and asks if any of the machines know they are using that particular IP address. When a machine recognizes the IP address as its own, it sends a reply so ARP can update the cache for future reference and proceed with the communication.
![Address Address](/uploads/1/3/3/2/133280739/555485819.jpg)
Host machines that don't know their own IP address can use the Reverse ARP (RARP) protocol for discovery.
An ARP cache size is limited and is periodically cleansed of all entries to free up space; in fact, addresses tend to stay in the cache for only a few minutes. Frequent updates allow other devices in the network to see when a physical host changes their requested IP address. In the cleaning process, unused entries are deleted as well as any unsuccessful attempts to communicate with computers that are not currently powered on.
Proxy ARP
Proxy ARP enables a network proxy to answer ARP queries for IP addresses that are outside the network. This allows packets to be successfully transferred from one subnetwork to another.
When an ARP inquiry packet is broadcast, the routing table is examined to find which device on the LAN can reach the destination fastest. This device, which is often a router, becomes a gateway for forwarding packets outside the network to their intended destinations.
ARP spoofing and ARP cache poisoning
Mac Address Stand For
Any LAN that uses ARP must be wary of ARP spoofing, also referred to as ARP poison routing or ARP cache poisoning. ARP spoofing is a device attack in which a hacker broadcasts false ARP messages over a LAN in order to link an attacker's MAC address with the IP address of a legitimate computer or server within the network. Once a link has been established, the target computer can send frames meant for the original destination to the hacker's computer first as well as any data meant for the legitimate IP address.
ARP spoofing can have serious impacts on enterprises. When used in their simplest form, ARP spoofing attacks can steal sensitive information. However, the attacks can also go beyond this and facilitate other malicious attacks, including:
History and future of ARP
ARP was first proposed and discussed in Request for Comments (RFC) 826, published in November of 1982 by David C. Plummer. The problem of address resolution was immediately evident in the early days of the IP protocol suite, because Ethernet quickly became the preferred LAN technology and Ethernet cables required 48-bit addresses.
In IPv6, network nodes use a protocol called Neighbor Discovery (ND) to acquire configuration information. Neighbor Discovery operates in the Link Layer (Layer 2) of the OSI model and uses Internet Control Message Protocol (ICMP) version 6 to discover neighboring nodes.
![Mac Mac](/uploads/1/3/3/2/133280739/925896387.jpg)
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Acronym | Definition |
---|---|
MAC | Media Access Control |
MAC | Macintosh (slang for Apple computer) |
MAC | Mandatory Access Control |
MAC | Medium Access Control |
MAC | Mid-American Conference |
MAC | Multiple Access |
MAC | Message Authentication Code |
MAC | Media Access Controller |
MAC | MPEG (Moving Picture Experts Group) Audio Collection |
MAC | Macro (File Name Extension) |
MAC | Medicare Administrative Contractor |
MAC | Mid-Atlantic Center for the Arts (tours & events; Cape May, NJ) |
MAC | Macau (ISO Country code) |
MAC | Macedonian (linguistics) |
MAC | Macaroni |
MAC | Mainland Affairs Council (Taiwan) |
MAC | Macomb (Amtrak station code; Macomb, IL) |
MAC | Metropolitan Airports Commission |
MAC | Military Affairs Council |
MAC | Milk and Cookies |
MAC | Mark McGwire (baseball player) |
MAC | Musical Arts Center |
MAC | Management Advisory Committee |
MAC | Make-Up Art Cosmetics, Inc |
MAC | Maximum Allowable Cost |
MAC | Mountain Athletic Conference (Pennsylvania high school athletics) |
MAC | Municipal Advisory Council |
MAC | Mining Association of Canada (l'Association Minière du Canada) |
MAC | McMaster University (Hamilton, Ontario, Canada) |
MAC | Mycobacterium Avium Complex (medicine) |
MAC | Moves, Adds, and Changes |
MAC | Marine Aquarium Council |
MAC | MacPaint (File Name Extension) |
MAC | Membrane Attack Complex |
MAC | Mobile Adult Content (conference) |
MAC | Media, Arts and Culture |
MAC | Marubeni America Corporation (Marubeni Corporation) |
MAC | Milwaukee Athletic Club (Milwaukee, WI) |
MAC | Immaculata |
MAC | Material Adverse Change |
MAC | Media Air Cleaner |
MAC | Mineral Area College (Park Hills, MO) |
MAC | Martial Arts Club (various organizations) |
MAC | Mount Aloysius College (Cresson, PA) |
MAC | Modal Assurance Criterion |
MAC | Managed Account (finance) |
MAC | Marketing Association of Columbia (Columbia University; New York) |
MAC | Monetary Affairs Committee (East African Community) |
MAC | Multnomah Arts Center (Portland, OR) |
MAC | Master of Accountancy |
MAC | Multnomah Athletic Club (Portland, OR) |
MAC | Military Airlift Command (US Air Force) |
MAC | Minimum Alveolar Concentration (measure of potency for anesthetics) |
MAC | Mass Attenuation Coefficient |
MAC | Morgan Advanced Ceramics (Morgan Crucible Company; UK) |
MAC | Monitored Anesthesia Care |
MAC | Mathematics and Computation (MIT Artificial Intelligence Lab project) |
MAC | Model Aircraft Club (various locations) |
MAC | Mouse Activated Computer |
MAC | Multi Access Computer |
MAC | Membership Advisory Committee |
MAC | Multiply Accumulate |
MAC | Macintosh |
MAC | Machine Access Code |
MAC | Multiple Advanced Computers |
MAC | Microsoft Approved Course |
MAC | Management Adhoc Committee |
MAC | Multiple Analogue Component |
MAC | Memory Access Control |
MAC | Mid-America Council (Boy Scouts of America; various locations) |
MAC | Mid-Atlantic Conference (various organizations) |
MAC | Missouri Arts Council (St Louis, MO) |
MAC | Master of Arts in Counseling |
MAC | Marine Amphibious Corps (est. 1942) |
MAC | Medium Access Controller |
MAC | Memory Access Controller |
MAC | Migration Authorisation Code (UK DSL) |
MAC | Mineralogical Association of Canada (Association Minéralogique du Canada) |
MAC | Maximum Allowable Concentration |
MAC | Main Automation Contractor |
MAC | Mid-America Chapter (various organizations) |
MAC | Municipal Athletic Complex (various locations) |
MAC | Move, Add, Change |
MAC | Multiplier/Accumulator |
MAC | Maximum Acceptable Concentration |
MAC | Military Assistance Command |
MAC | Medical Associates Clinic (various locations) |
MAC | Model Articulation Controller |
MAC | Mildura Arts Centre (Australia) |
MAC | Munich Airport Center |
MAC | Management Advisory Council (FAA) |
MAC | Marginal Abatement Cost (curve; metric of costs of complying with Kyoto Protocol for reducing greenhouse gases) |
MAC | Manufacturing Assistance Center (various locations) |
MAC | MacConkey Agar (microbiological media) |
MAC | Market Access and Compliance (US Department of Commerce) |
MAC | Morrisville Auxiliary Corporation (Morrsiville State College; Morrisville, NY) |
MAC | Mid-America Conference |
MAC | Maryland Athletic Club |
MAC | Multi Activity Court (various locations) |
MAC | Motor Ambulance Convoy |
MAC | Medical Advisory Council |
MAC | Multiple Award Contracts |
MAC | Municipal Assistance Corporation (New York City) |
MAC | Mean Aerodynamic Chord |
MAC | Michigan Association of Counties |
MAC | Membership Advisory Council (various organizations) |
MAC | Multi-Agency Coordinating (various organizations) |
MAC | Midwest Archives Conference |
MAC | Methanosarcina Acetivorans |
MAC | Manhattan Association of Cabarets and Clubs |
MAC | Mine Action Center |
MAC | Multi Asset Class (Oberon Financial Technology, Inc.) |
MAC | Mid-Atlantic Championship |
MAC | Maximum Allowable Charge |
MAC | Maintenance Allocation Chart |
MAC | Memory and Aging Center |
MAC | Mid-Atlantic Crossing |
MAC | Mobile Air Conditioner |
MAC | Magnetic Accelerator Cannon (Babylon 6) |
MAC | Mooney Airplane Company (Texas) |
MAC | Mines Action Canada |
MAC | Military Armament Corporation (produced Mac 10&11 SMGs) |
MAC | Michigan Administrative Code |
MAC | Mitral Annular Calcification (echogardiography) |
MAC | Atlantic Mackerel (FAO fish species code) |
MAC | Maintaining Active Citizens (elderly care; various locations) |
MAC | Machine Aided Cognition |
MAC | Manitoba Arts Council |
MAC | Minnesota Annual Conference |
MAC | Multicultural Advisory Committee |
MAC | Music Appreciation Club (various locations) |
MAC | Methodist Annual Conference |
MAC | Military Aircraft Command |
MAC | Members Advisory Committee (various organizations) |
MAC | Multi Agency Committee (various locations) |
MAC | Mexican-American Commission |
MAC | Midwest Airlines Center (now Frontier Airlines Center; Milwaukee, WI) |
MAC | Master Addictions Counselor |
MAC | Mid America Corvette (company) |
MAC | Multiplexed Analogue Components |
MAC | Medical Alumni Council (various schools) |
MAC | Management Access Conference (annual conference) |
MAC | Muslim Association of Canada (Ottawa, Canada) |
MAC | Monitoring Advisory Committee (various locations) |
MAC | Maintaining Arc Consistency (constraint programming AI research) |
MAC | Mary Andrews College (Australia) |
MAC | Michigan Apple Committee |
MAC | Montgomery Aquatic Center (Rockville, MD) |
MAC | Midtown Athletic Club (various locations) |
MAC | Machine Address Code |
MAC | Marketing Advisory Committee |
MAC | Mission Assurance Category |
MAC | Massachusetts Animal Coalition |
MAC | Management Accounting Committee (various organizations) |
MAC | Months After Contract |
MAC | Manufacturing Alliance of Connecticut |
MAC | Mid-Arm Muscle Circumference |
MAC | Mapping and Analysis Center (FEMA) |
MAC | Maintenance Advisory Committee (various organizations) |
MAC | Minnesota Autosports Club (est. 1970) |
MAC | Metropolitan Arts Commission |
MAC | Ministry of Agriculture and Cooperatives |
MAC | Monitoring and Analysis Coordinator (US FEMA) |
MAC | Moore Action Collectibles (toy company) |
MAC | Mikuni American Corporation (Northridge, CA) |
MAC | Michigan Aerospace Corporation (Ann Arbor, Michigan) |
MAC | Monitored Anaesthesia Care |
MAC | Mine-Awareness Campaign |
MAC | Mothers Against Canada (South Park) |
MAC | Money Access Center |
MAC | Maximum Amount Contributable (US IRS) |
MAC | Microbiota-Accessible Carbohydrate (biological molecules) |
MAC | Mothers Against Circumcision |
MAC | Mississippi Association of Cooperatives |
MAC | Multi Axis Controller |
MAC | Minister’s Approval Certificate (UK) |
MAC | Multipole Acoustic Log (energy production) |
MAC | Mixed Armistice Commission |
MAC | Multiservice Access Concentrator (ADC Kentrox) |
MAC | Minimum Annual Commitment |
MAC | Masonry Advisory Council |
MAC | Message Authenticity Check |
MAC | Mobility Augmentation Company (US Army) |
MAC | Midwest CHP Application Center |
MAC | Mediterranean Air Command (WWII) |
MAC | Midwest Adoption Center (Des Plaines, IL) |
MAC | Maningrida Arts and Culture (Aboriginal arts organisation; Maningrida, Arnhem Land, Northern Territory) |
MAC | Making Arizona Competitive |
MAC | Management and Administrative Computing |
MAC | Munitions Assembly Conveyor |
MAC | Ma’aden Aluminum Company (Ras Az Zawr, Saudi Arabia) |
MAC | Mouse Activated Computer (suggested acronym for Apple Macintosh computer) |
MAC | Multiple-Access Computing |
MAC | Maine Athletic Conference |
MAC | Master of Art Conservation |
MAC | Maintenance Action Code |
MAC | Manchester Athletic Club (Manchester, MA) |
MAC | Multiple Analog Component |
MAC | Multipurpose Activity Center |
MAC | Mississauga Arts Council |
MAC | Mitigation Assistance Clinic (US FEMA) |
MAC | Mobile Action Command (1970s Matchbox Division) |
MAC | Mid-Atlantic Collegiate (umpires) |
MAC | Multiple Access Communications Limited |
MAC | Mobile Attenuation Code (cellular term) |
MAC | Medical Assistance for Children (various organizations) |
MAC | Movimento Anti-Comunista (Portuguese: Anti-Communist Movement) |
MAC | Mean Alveolar Concentration (anesthesiology) |
MAC | Multicultural Awareness Council |
MAC | Museu da Arte Contemporânea (Sao Paulo, Brazil) |
MAC | Mean Aerodynamic Center |
MAC | Medical Affirmative Claims |
MAC | Mobility Augmentation Company |
MAC | Mission Assignment Coordinator |
MAC | Maneuver Area Command |
MAC | Multi Access Controller |
MAC | Multiphase Atmospheric Chemistry |
MAC | Medicaid Authorization Card |
MAC | Multi Aircraft Control (aviation technology) |
MAC | Montana Agricultural College |
MAC | Micromechanics Analysis Code (US NASA software) |
MAC | Middle America Cox (Cox-Internet) |
MAC | Message Authentication Control |
MAC | Maintenance Administration Center |
MAC | Mass Accelerator Cannon (gaming, Halo weaponry) |
MAC | Magazine Association of Canada |
MAC | Municipal Amateur Coordinator |
MAC | Multiplier Accumulator Chip |
MAC | Multiplying Accumulator |
MAC | Manufacturing Advisory Center |
MAC | Management Ad Hoc Committee |
MAC | Major Ambulatory Category |
MAC | Minimal Antibiotic Concentration |
MAC | Multifiber Array Connector |
MAC | Multi-Agency Coordinating Entity |
MAC | Management Action Center |
MAC | Major Area Commander |
MAC | Makiling Airsoft Club (Philippines) |
MAC | Multiple Architecture Computer (Hewlett-Packard) |
MAC | Material Accumulation Costing |
MAC | Materiel Acquisition Command |
MAC | Material Accountability and Control |
MAC | Multi-Sensor Air Campaign |
MAC | Maritime Area Commander |
MAC | Measurement and Analysis Center |
MAC | Maintenance Availability Computer |
MAC | Multiple Access Contract |
MAC | Manitoba Action Centre (Leaf Rapids, Manitoba, Canada) |
MAC | Mechanized Assignment and Control |
MAC | Magnetic Anomaly Concealment |
MAC | Material Accounting Center |
MAC | Chief Machine Accountant (naval rating) |
MAC | Moselle Alpine Club (French automobile club; Moselle, France) |
MAC | Maximum Adjacent Cut (locksmithing) |
MAC | Metal Anneal Chamber |
MAC | Montessori Australia Council (Queensland, Australia) |
MAC | Modular Amplification Card |
MAC | Mortuary Affairs Coordinator |
MAC | Multiple Array Correlation |
MAC | Mobile Attack Cuisine (Fighting Foodons) |
MAC | Modern Arab Contractors |
MAC | Milestone Achievement Certificate (UK) |
MAC | Multi-Static Active Coherent (US Navy) |
MAC | Mainland Aviation College (New Zealand) |
MAC | Men's Advisory Counsel/Committee (prisons) |
MAC | Mustang Athletic Complex |
MAC | MIUW Attack Craft |
MAC | Magnetometer Alignment Coil |
MAC | Manually Activated Call point (fire protection systems) |
MAC | Minneola Alliance Church (Minneola, FL) |
MAC | Maximum Asset Capability (economics) |
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