mac address oui assignment

OUI Lookup Tool

The Wireshark OUI lookup tool provides an easy way to look up OUIs and other MAC address prefixes. It uses the Wireshark manufacturer database , which is a list of OUIs and MAC addresses compiled from a number of sources.

Directions : Type or paste in a list of OUIs, MAC addresses, or descriptions below. OUIs and MAC addresses may be colon-, hyphen-, or period-separated.

Examples : 0000.0c 08:00:20 00-00-0C-CC-CC-CC 00d9.d110.21f9 missouri

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MAC Address Lookup

Sample MAC Address 40-A8-F0-4F-50-9E or OUI 40-A8-F0

MAC Lookup - Find MAC Address / OUI / Vendor Details

MAC (Address) Lookup is a powerful tool that enables users to identify the manufacturer or vendor of a network device by analyzing its MAC. You can also do a MAC Vendor lookup or OUI (Organizational Unique Identifier) lookup with this tool

The MAC lookup tool is extremely simple to use. Its intuitive UI and minimalist approach lends itself to ease of use..

How to Do a MAC Address / Vendor / OUI Lookup With Our Tool?

Follow the given steps to find the OUI and other relevant details from a MAC address.

• Access the MAC Address Lookup tool.
• Input the MAC Address (like 40-A8-F0-4F-50-9E) or OUI (like, 40-A8-F0) into the designated field to check its mac address details or vendor / OUI details. Make sure that each MAC address is on a new line (max 10 entries at once).
• Click the search button to get your results.

You will see a detailed output sheet. This is the information provided by it.

An Explanation of the Results

After doing an OUI lookup, you will see the following information.

• Address Prefix. This is the OUI number
• Vendor/Company. This is the name of the company that issued the NIC.
• Start address. This shows the beginning of the range of serial numbers that the vendor can issue.
• End address. This shows the end of the range of serial numbers that the vendor can issue.
• Company address. This shows the real address of the vendor that issued the NIC.

Below these results will be another menu that provides extra details. They are categorized into three sections, namely: Vendor Details, Block Details, and MAC history. Here is what each section shows.

Vendor Details

• Address Prefix. This is the first three octets (Or six characters) of the MAC address. This is specific for each company.
• Vendor/Company. This shows the name of the company to whom the address prefix is assigned.
• Company Address. The address of the company.
• Is Private? Shows whether the address prefix is private or public
• Country Code. Shows the country code to which the company belongs.

Block Details

A MAC address block is the specific range of addresses that are assigned to a manufacturer. This part of the results shows the block details.

• Is Registered? Shows whether the block is registered or not.
• Start Address. Show the starting address of the block.
• Assignment Block Size. Shows classification of the block size. MA-L is a large block reserved for enterprises.
• Date Created. Shows the date on which the block was registered
• Block Size. This shows the total number of MAC addresses available in that block. MA-L means that 16,777,216 addresses are available.
• End Address. Shows the last address on the block.
• Date Updated. Shows the date on which the block’s registration was changed or updated.

MAC History

The MAC history shows the visual timeline of when the MAC address block was registered and updated. 

The changes are clearly labeled. For example, if the company address changes, the new address will be given. If the vendor name changes, it will be mentioned. 

Due to the focus on vendor information, a MAC address lookup is also known as a MAC vendor lookup or MAC address vendor lookup.

How Does Our MAC Vendor Lookup Work?

Our MAC Vendor Lookup tool utilizes a vast public database (courtesy of the IEEE) to retrieve information about a MAC address, including the original manufacturer, prefix, postfix, and country of origin.

The vendor number (OUI) in a MAC address is assigned by the IEEE . The IEEE maintains a public database that lists the details of all the MAC address blocks they have sold/leased to companies.

Our MAC Vendor lookup tool accesses this database and finds the MAC address block, which contains the inputted MAC address. Then, it pulls the relevant details from the database and outputs them to the user in a clear and straightforward format.

When you are doing a “Search by Vendor,” the tool simply checks the name of the company you inputted and pulls the address blocks associated with that MAC vendor.

What is a MAC Address?

MAC stands for Media Access Layer. A MAC address is a unique identifier for network interface cards (NICs) in a device. The most common NICs are for WiFi routers, Ethernet, and Bluetooth devices.

MAC address consists of 12 hexadecimal characters. It is used for secure network communication.

As you know, devices on the internet have a public IP address. However, one access point with one public IP can have multiple devices connected to it. MAC addresses are used to identify the specific device behind a public IP that needs to be communicated with.

What is OUI in a MAC Address?

The first six characters in the MAC address are called OUI or organizationally unique identifiers. They identify the organization that created the NIC. The last six digits are specific to the NIC itself and act as its serial number.

What is the Vendor Number in a MAC Address?

The vendor number is just another name for the OUI number. The IEEE assigns specific ranges of vendor numbers to each company. To use the OUI numbers a company needs to purchase them from IEEE. It is possible for a company to be assigned multiple OUIs if they purchase more blocks from IEEE.

What are the Features of our MAC Address Lookup Tool?

Our OUI lookup tool is chock full of useful features that enhance its usability and function. All of the features are listed below.

• Detailed results. Users see a detailed output.
• Multiple MAC Address Lookup. It is possible to look up multiple MAC addresses simultaneously.
• Copy Results Quickly. Users can use the copy shortcut button to quickly save their results in a different file.
• Download Results Instantly. The download button lets you save the file on your device in either JSON or CSV format. This is great for programmers and system admins who need to feed the results into some software.
• Multiple Language Support. Users can view their results in three different languages: English, Dutch, and Russian.
• Free to Use. The MAC address lookup tool is completely free to use. It does not have any requirements to register and pay before use.
• Accurate and Up-to-Date Database
• User-Friendly Interface
• Fast Response Time
• Multiple Input Formats
• API Availability
• Privacy and Security
• Mobile Friendly
• No Subscription Fees

Frequently Asked Questions (FAQs)

What information can i get using the mac lookup tool.

A MAC address lookup can provide details about the manufacturer or vendor of a MAC address. This comprises information such as the company name, address, etc.

Is our tool for looking up MAC addresses free to use?

You can access it for free whenever you need to look up a MAC address. There’s no need for a premium subscription to use any of the features.

Is it legal to use a MAC address finder?

Yes, using a MAC address finder is legal. It can be used for network troubleshooting, inventory management, network security, and other practical applications.

Can I identify the device by MAC address online?

You can look up MAC addresses for devices on any network as long as you can access the device's MAC address and our MAC address finder.

Can the MAC address be represented in binary format?

Typically, MAC addresses are represented in binary format. A MAC address has 48 bits (6 bytes) and is typically expressed as six pairs of hexadecimal integers separated by colons or hyphens. Each hexadecimal digit corresponds to 4 bits, giving a MAC address of 12 hexadecimal characters.

A MAC address such as "00:1A:2B:3C:4D:5E" can be represented in binary as follows: 00000000:00011010:00101011:00111100:01001101:01011110

Each pair of hexadecimal numerals corresponds to an 8-bit binary value in this representation. The binary format is beneficial for low-level network operations and calculations involving MAC addresses.

Instructions/Notes

Click to learn more about MAC Address & OUI 

Every device that communicates on a network is assigned a unique 6-byte (48-bit) Media Access Control (MAC) address by the manufacturer. This address, also called a hardware address or physical address, is baked onto the ROM firmware (sometimes referred to as the burned in address) of the network card, router, firewall, network switch, wireless access point, and other networking devices manufactured.

Manufacturers are all assigned a unique set of 3-byte codes called the Organizationally Unique Identifier (OUI ). The 3-byte code (sometimes referred to as a vendor code) becomes the first three bytes (aka octets) of the 6-byte MAC address. The last three bytes is a unique value that the manufacturers assigns themselves (e.g., the serial number). No two network devices/cards in the world should have the same MAC address. If there happens to be two network devices/cards with the same 6-byte MAC address and they happen to be on the same network, reliable network communication cannot take place.

Where to Find Your MAC Address

Mac address example.

00-0F-66-D0-69-13 (can also be written as 000F.66D0.7654 or as 00:0F:66:D0:69:13)

In this example, the first 3-byte code (00-0F-66) is the OUI and identifies Linksys/Cisco as the manufacturer. The last three-byte code (D0:69:13) identifies the unique unit Linksys/Cisco manufactured.

With this arrangement, MAC address will uniquely identify a specific network device/card in the world. The first three bytes identifies the manufacturer and the last three bytes identifies the specific device unit and potentially identify the customer it is registered with.

Result & Lookup History (10 Maximum)

Manufacturer's oui list.

Computer Networking: Collection Of Three Books

IANA OUI Ethernet Numbers

Registries included below

IANA Unicast 48-bit MAC Addresses

Iana multicast 48-bit mac addresses, iana 64-bit mac addresses, the cfxxxx series, snap protocol numbers, iana link layer discovery protocol (lldp) tlv subtypes, iana mac address block.

Contact Information

MAC address vendor/manufacturer lookup tool

Mac address, general info.

A media access control address is a unique 48-bit identifier assigned to a network interface controller. It is used on data link layer (layer 2 of OSI model) of computer networking as a network address. MAC addresses are assigned by device manufacturers and usually includes manufacturer's 24-bit OUI (Organizationally Unique Identifier). Now they refers as EUI-48 identifiers.

Address details

48-bit address MAC address starts with 24-bit OUI, 28-bit OUI-28/MA-M or 36-bit OUI-36/MA-S identification numbers. IEEE 802 standard format for printing Extended Unique Identifiers (EUI-48) is six groups of two hexadecimal digits separated by hyphens.

Institute of Electrical and Electronics Engineers (IEEE)

Location: piscataway, new jersey, united states of america.

IEEE is the world's largest technical professional organization dedicated to advancing technology for the benefit of humanity. IEEE Registration Authority deals with assigning unique identifiers to manufacturers. Obtaining registered identifiers is payable and cost depends on below block size:

• MAC Address Block Large (MA-L)
• MAC Address Block Medium (MA-M)
• MAC Address Block Small (MA-S)

Trivia Facts

Here are some interesting trivia facts about mac address lookup, vendor identification.

MAC address lookup can reveal the manufacturer or vendor of a network interface card (NIC) based on its MAC address. The first six characters of a MAC address, known as the OUI (Organizationally Unique Identifier), are assigned to specific manufacturers by the IEEE (Institute of Electrical and Electronics Engineers).

MAC addresses are intended to be globally unique identifiers for network interfaces. However, in practice, there have been instances of MAC address collisions, where two network interfaces have the same MAC address. Such occurrences are rare but can potentially cause network connectivity issues.

Permanent vs. Changeable

MAC addresses are typically hardcoded into network interface hardware and are considered permanent. However, some network interfaces, particularly in consumer devices like smartphones and laptops, allow users to change their MAC addresses through software settings. This process is known as MAC address spoofing.

Layer 2 Addressing

MAC addresses are used at the Data Link layer (Layer 2) of the OSI model for addressing devices within the same local network segment. They are crucial for facilitating communication between devices on the same network, such as Ethernet LANs.

ARP Protocol

Address Resolution Protocol (ARP) is used in IPv4 networks to map IP addresses to MAC addresses. When a device needs to communicate with another device on the same network, it uses ARP to determine the MAC address corresponding to the destination IP address.

MAC Address Filtering

MAC address lookup is often used in network security for MAC address filtering. Network administrators can configure routers and switches to only allow specific MAC addresses to access the network, thereby enhancing security by restricting access to authorized devices.

MAC Address Privacy Concerns

While MAC addresses are essential for network communication, they can also raise privacy concerns. Persistent tracking of MAC addresses in public Wi-Fi networks or other contexts can be used for surveillance or targeted advertising purposes, leading to debates around user privacy and data protection.

These trivia bits provide insights into the role, characteristics, and implications of MAC address lookup in networking and security contexts. Fascinating, isn’t it?

IEEE.org  |  IEEE Xplore Digital Library  |  IEEE Standards  |  IEEE Spectrum  |  More Sites

Guidelines for Use of Extended Unique Identifier (EUI), Organizationally Unique Identifier (OUI), and Company ID (CID)

• April 01, 2022 20:28

This tutorial covers organizational identifiers assigned by the IEEE Registration Authority (IEEE RA) and extended identifiers based on them. It covers identifier formats, assignment, guidelines, and policies relevant to assignees as well as to standards developers. The tutorial includes information relevant to organizational identifiers, such as Organizationally Unique Identifier (OUI) and Company ID (CID), and to extended identifiers such as the Extended Unique Identifier (EUI) and Extended Local Identifier (ELI).

Status and History

This tutorial supersedes the following three IEEE RA tutorial documents:

• Guidelines for Use Organizationally Unique Identifier (OUI) and Company ID (CID)
• Guidelines for 48-Bit Global Identifier (EUI-48)
• Guidelines for 64-bit Global Identifier (EUI-64)

IEEE-Administered organizational identifiers: OUI and CID

Extended identifiers, extended unique identifiers, extended local identifier (eli), ieee ra assignment of identifiers, eui structure and representation, eui bit ordering, unassigned and null eui values, appropriate eui use, maintaining longevity of eui-48 and eui-64, non-overlapping assignments, ieee ra policies to reduce the volume of unused eui-48s, mapping an eui-48 to an eui-64, other worldwide identifiers based on eui, context dependent identifiers, restrictions on the use of context dependent identifiers.

Deprecated and Obsolete Identifiers.

The IEEE Registration Authority (IEEE RA) assigns globally unique identifiers to organizations. Two types of identifier– the 24-bit Organizationally Unique Identifier (OUI) and the 24-bit Company ID (CID)– are related to each other in that they come from the same 24-bit space but fall in different subspaces, as distinguished by a particular bit known as the X bit, as shown in Table 1. The X bit location is shown in Figure 1. Each assigned OUI and CID and is unique with respect to all assigned OUIs and CIDs 1

An OUI or a CID may be used for identification of a company, organization, entity, manufacturer, vendor, etc. The IEEE Registration Authority also recognizes and assigns a 36-bit OUI-36 as a globally unique identifier of an organization. The first 24 bits of the assigned OUI-36 do not duplicate any OUI or CID assignment.

The OUI is a 24-bit (three octet) sequence. The structure of an OUI is shown in Figure 1. Octet 0 is the initial (most significant) octet. The least and second least significant bits of Octet 0 are designated the M bit and X bit, respectively. In the OUI, both the M and X bit have the value 0. NOTE – Approximately 18 organizational identifiers assigned to early Ethernet implementers (some of the BlockID assignments made prior to approval of IEEE Std 802.3-1985) have the X bit equal to 1. The BlockID, like the OUI that replaced it, was a 24-bit number that served as the base for a block of 2 24 48-bit MAC addresses. The BlockID assignments are recorded in the MA-L (OUI)registry.

The OUI can be represented as a base-16 number of six hexadecimal digits. Alternatively, it can be represented as octets separated by hyphens; the IEEE RA refers to this as the hexadecimal (hex) representation. Table 2 displays an example of the OUI with the base-16 form “ACDE48” and the hex representation “AC-DE-48” 2 . The last row of Table 2 represents the 24-bit binary OUI sequence.

The OUI-36 is a 36-bit (four-and-one-half-octet) sequence. Octet 0 is the initial (most significant) octet. The least and second least significant bits of Octet 0 are designated the M bit and X bit, respectively. In the OUI-36, both the M and X bit have the value 0.

An OUI-36 assignment may be used where a 36-bit organization identifier or 36-bit protocol identifier is needed. For example, some protocols specify 36-bit identifiers to identify either an organization or objects specified by that organization. The assignee of an OUI may create an OUI-36 by adding 12 bits to the end of the assigned OUI. If the assignee of an OUI-36 needs a unique 24-bit organization identifier, a CID assignment is recommended.

The OUI-36 can be represented as a base-16 number of nine hexadecimal digits. Alternatively, it can be represented as octets separated by hyphens, using the IEEE RA hexadecimal (hex) representation. Table 3 displays an example of the OUI-36 with the base-16 form “ACDE48234” and the hex representation “AC-DE-48-23-4”. The last row of Table 3 represents the 36-bit binary OUI-36 sequence.

An OUI-36 is created by the IEEE RA by concatenating 12 bits to a 24-bit IEEE-reserved base OUI, concatenating these 12 bits after the least significant bit of Octet 2, as shown in Figure 1. The base OUI will not be assigned to another organization or otherwise be used as an OUI. An assignee of an OUI36 shall not truncate the OUI-36 to use as an OUI because the IEEE RA will use the base OUI to assign OUI-36 values to multiple organizations.

No presumptions should be made regarding the base OUI. For example, it should not be presumed that multiple OUI-36 assignments to a single organization will share a common base OUI.

The CID is a 24-bit (three-octet) sequence. The structure of a CID is shown in Figure 2 below. Octet 0 is the initial (most significant) octet. The four least significant bits of Octet 0 are designated the M bit, X bit, Y bit, and Z bit, respectively, beginning with the least significant bit. In the CID, the M, X, Y, and Z bits have the values 0, 1, 0, and 1, respectively.

The CID can be represented as a base-16 number of six hexadecimal digits. Alternatively, it can be represented by octets separated by hyphens, in the IEEE RA hexadecimal (hex) representation. Table 4 displays an example of the CID with the base-16 form “AADE48” and the hex representation “AA-DE-48” 3 . The last row of Table 4 represents the 24-bit binary CID sequence.

In addition to serving as a globally unique organization identifier, an OUI, OUI36, or CID may also be used as the basis of extended identifiers, including protocol identifiers and context dependent identifiers, by concatenating additional differentiating bits. These extended identifiers might be globally unique (e.g., EUI-48 and EUI-64) or only unique within the context in which they are used. Details are provided below.

An Extended Unique Identifier (EUI) is either a 48-bit Extended Unique Identifier (EUI-48) or a 64-bit Extended Unique Identifier (EUI-64). With some exceptions, particularly with regard to protocol identifiers, each EUI is intended to be globally unique and bound to a hardware device instance or other object that requires unique identification. EUI-48 and EUI-64 identifiers are most commonly used as globally unique network addresses (sometimes called MAC addresses), as specified in various standards. For example, an EUI48 is commonly used as the address of a hardware interface according to IEEE Std 802, historically using the name “MAC-48”. As another example, an EUI64 may serve as the identifier of a clock, per IEEE Std 1588. IEEE Std 802 also specifies EUI-64 use for 64-bit globally unique network addresses. Further detail regarding EUI-48 and EUI-64 is provided below.

When an EUI is used as a MAC address (for example, an IEEE 802 network address), the two least significant bits of the initial octet (Octet 0) are used for special purposes. The least significant bit of Octet 0 (the I/G bit) indicates either an individual address (I/G=0) or group address (I/G=1), and the second least significant bit of Octet 0 (the U/L bit) indicates universal (U/L=0) or local (U/L=1) administration of the address. A universally administered address is intended to be a globally unique address.

In an EUI created by extending an OUI, the OUI is the initial (most significant) three octets. In an EUI created by extending an OUI-36, the OUI-36 is the initial (most significant) four and a half octets.

Since OUI and OUI-36 assignments made by the IEEE RA have the X bit equal to 0, an EUI created as an extended identifier from an assigned OUI or OUI-36 has U/L=0 and, when used as a MAC address, is thus a universally administered address.

Since all OUI and OUI-36 assignments made by the IEEE RA have the M bit equal to 0, an EUI created as an extended identifier from an assigned OUI or OUI-36 has I/G=0 and, when used as a MAC address, is thus an individual address.

The assignee of an OUI or OUI-36 is exclusively authorized to assign group MAC addresses, with I/G=1, by extending a modified version of the assigned OUI or OUI-36 in which the M bit is set to 1. Such addresses are not EUIs and do not globally identify hardware instances, even though U/L=0.

An Extended Local Identifier (ELI) is created by concatenation from a CID, which comprises the initial three (most significant) octets. The ELI-48 is a 48-bit ELI and the ELI-64 is a 64-bit ELI.

Since CID assignments made by the IEEE RA have the X bit equal to 1, an ELI created as an extended identifier from an assigned CID has U/L=1 and is thus, when used as a MAC address, a local address. Local addresses are not globally unique, and a network administrator is responsible for assuring that any local addresses assigned are unique within the span of use. (Uniqueness of local addresses typically does not need to extend beyond a router.) IEEE Std 802 (beginning with the amendment IEEE Std 802c-2017) specifies the Structured Local Address Plan (SLAP), which describes the use of ELIs in one quadrant of local MAC address space, based on the specified values of the CID Y bit and Z bit. In other quadrants of local MAC address space, the SLAP describes the use of Standard Assigned Identifiers (SAIs) and Administratively Assigned Identifiers (AAIs) not based on a CID.

Since all CID assignments made by the IEEE RA have the M bit equal to 0, an ELI created as an extended identifier from an assigned CID has I/G=0 and is thus, when used as a MAC address, an individual address. The assignee of a CID may assign local group MAC addresses by extending a modified version of the assigned CID by setting the M bit to 1 (so that I/G=1). The resulting extended identifier is an ELI.

An assigned EUI block can be viewed as a sequence of numbers extended from a base number (e.g., OUI) by concatenation of an extension identifier. It can also be described as a contiguous range of EUI-48 or EUI-64.

EUI blocks are assigned by the IEEE RA in three different sizes. The MA-L assignment block provides both 2 24 EUI-48 identifiers and 2 40 EUI-64 identifiers. The MA-M assignment block provides both 2 20 EUI-48 identifiers and 2 36 EUI-64 identifiers. The MA-S assignment block provides both 2 12 EUI-48 identifiers and 2 28 EUI-64 identifiers.

The MA-L assignment includes the assignment of the OUI that is the base for the assigned EUI-48 and EUI-64 extended identifier blocks. An MA-L is equivalent to an OUI assignment made prior to January 1, 2014, which also included assignment of both an OUI and the associated blocks of EUI-48 and EUI-64 identifiers.

The MA-S assignment includes the assignment of the OUI-36 that is the base for the assigned EUI-48 and EUI-64 extended identifier blocks. The MA-S does not include assignment of a 24-bit OUI. The 24 initial bits of the assigned MAS block is an OUI assigned to the IEEE RA.

NOTE – The MA-S assignment became available January 1, 2014. The MA-S assignment replaced both the Individual Address Block (IAB) and the OUI-36 assignments offered by the IEEE RA prior to January 1, 2014. The IAB came only with a block of 4096 EUI-48 identifiers and did not provide any other identifiers, e.g., EUI-64 identifiers; see the sub-section “IAB-Based Identifiers” later in this tutorial.

The MA-M does not include assignment of an OUI. The assignee of the MA-M may create an OUI-36 as the first 36 bits of an address in the MA-M assignment block. If the assignee of an MA-M needs a unique 24-bit organization identifier, a CID assignment is recommended. The first 24-bits of the assigned MA-M block are an OUI assigned to IEEE that will not be reassigned.

NOTE – The MA-M assignment became available January 1, 2014 in response to customer requests for an intermediate block of identifiers.

The CID assignment is of a single unique 24-bit identifier usable to identify a company, organization etc. The CID assignment does not include any EUI-48 or EUI-64 assignments, and a CID shall not be used to create an EUI-48 or EUI-64. A CID could be complementary to an MA-M or MA-S assignment for an entity seeking a unique 24-bit identifier, because those assignments do not include an OUI.

The OUI, OUI-36, CID, EUI-48 and EUI-64 assignments available from the IEEE RA are summarized in Table 5.

The assignee of the IEEE identifier is responsible for administering the extension identifiers within its assigned block. The IEEE RA has no control over the assignments of the extension identifiers and assumes no liability for  assignments of duplicate extension identifiers by an organization using an IEEE-assigned identifier (e.g., duplicate context dependent identifiers, EUI-48, or EUI-64 values).

The assignments of the IEEE-administered identifiers in Table 5 are typically public and available from the IEEE RA, so that an interested user can identify the registered owner of an EUI-48, EUI-64, OUI, OUI-36, or CID 4 . However, for assignees electing to use the private listing option, the IEEE assignment, but not identity of the assignee, is publicly available.

Table 6 illustrates the structure of the EUI-48 and its relationship to the assignments made by the IEEE RA.

An EUI-48 is a string of six octets, labeled in Table 6 from Octet 0 (initial and most significant) through Octet 5 (final and least significant). Table 6 includes, in the final two rows, an example EUI-48 with the base-16 form “ACDE48234567” and the hex representation “AC-DE-48-23-45-67”. Note than an EUI-48 can be represented in the IEEE RA hexadecimal (hex) form with the octets separated by hyphens, or as a pure base-16 numerical representation without hyphens. It may also be represented as a binary number or sequence, as illustrated.

Table 6 illustrates examples of how EUI-48 might have arisen following: an MA-L assignment with the OUI AC-DE-48, and an entity assignment of the extension identifier of 23-45-67; an MA-M assignment with the base AC-DE48-2, and an entity assignment of the extension identifier of 3-45-67; and an MA-S assignment with the OUI-36 AC-DE-48-23-4, and an entity assignment of the extension identifier of 5-67.

EUI-64 is represented similarly, as a string of eight octets, from Octet 0 (initial and most significant) through Octet 7 (final and least significant). This is shown in Table 7, using the example EUI-64 with the base-16 form “ACDE48234567019F” and the hex representation “AC-DE-48-23-45-67-01- 9F”.

While the order of the EUI octets, and the bits within the octets, is specific and fixed, the sequence of their transmission can vary based on the protocol. Typically, octet-based transmissions transmit in ascending order of octet identifiers, beginning with octet 0. Some block codes encode multiple octets. Bit-serial encodings of data may differ in the ordering of bit transmissions within octets. Likewise, the order of address storage in memory can vary depending on the protocol. Further information on bit transmission order is available in relevant standards, such as IEEE Std 802.

Given the possible confusion of bit ordering and byte positioning, applications and protocols must unambiguously specify a mapping of the identifier value (expressed as hexadecimal digits) to the applicable register or byte and bit sequence. To ensure clarity, each mapping should be self-contained. If it is deemed necessary to cross-reference other documents, the specific document and page number shall be cross-referenced, so that unfamiliar readers can easily find the source.

To avoid changes in existing standards, a working group may alternatively provide tutorials on any uses of identifiers in its standards, to be posted on the IEEE RA web site.

If a standard, or its cross-referenced portions of other standards, does not conform to these documentation policies, the IEEE Registration Authority Committee (RAC) can recommend the standard not be approved.

Many applications have found it useful to define a distinct null identifier, most often indicating the absence of a valid EUI-48 or EUI-64 value. As an example, a null value might be the power-on state for an integrated circuit register, until the hardware or firmware initializes the register with a valid EUI. Similarly, where the EUI of another device or object is placed in a protocol field, a null value may be used until the valid EUI value to be placed in the protocol field is learned. A management information base parameter also may face a similar initial-value issue making use of a null value convenient.

The all-zeros EUI-48 value (00-00-00-00-00-00) and EUI-64 value (00-00-00-00-00-00-00-00), though assigned to an organization, have not been and will not be used by that assignee as an EUI. (They can be considered as assigned to the IEEE Registration Authority.) The all-ones 48-bit value (FF-FF-FF-FF-FFFF) and 64-bit value (FF-FF-FF-FF-FF-FF-FF-FF) are IEEE 802 multicast (group) MAC addresses indicating all stations on a network. These all-ones values are not valid EUIs.

The recommended null values are FF-FF-FF-FF-FF-FF and FF-FF-FF-FF-FF-FFFF-FF, as defaults for unknown EUI-48 and EUI-64 values, respectively. Values based on a zero-valued OUI, such as 00-00-00-00-00-00 and 00-00-00-00-00-00-00-00, shall not be used as identifiers.

EUIs are intended to be used in applications that require fixed-size globally unique identifiers.

Except in certain cases, such as protocol identifiers, an assignee associates an EUI-48 or EUI-64 with a single identifiable object (e.g., a network interface). Depending on the functions supported by a device, it may use more than one identifier. For example, a smart phone could have an EUI-48 used as the 802.11/Wi-Fi® MAC address and a second identifier for the Bluetooth® interface. An Ethernet connected device could have an EUI-48 MAC address Guidelines for Use of EUI, OUI, and CID 2017-08-03 12 and an EUI-64 that uniquely identifies an 802.1AS clock (i.e., a “clockIdentity”.)

The EUI-64 is used instead of EUI-48 to avoid excess consumption of OUI values within high-volume, particularly non-networking, applications. Given the minimal probability of consuming all EUI-64 identifiers, the IEEE RA places minimal restrictions on their use within standards. Unless mandated by backward-compatibility constraints, the use of EUI-64 is preferred to the use of EUI-48. However, for backward compatibility, this transition may be difficult for some IEEE 802-related applications (e.g., new networks that need to bridge to 48-bit IEEE 802 networks). Therefore, selective use of 48-bit identifiers within 802-related systems will be considered by the IEEE Registration Authority Committee. See  Maintaining Longevity of EUI-48 and EUI-64” below for further details.

The terms EUI-48 and EUI-64 are trademarked by IEEE. Organizations are allowed limited use of these terms for commercial purposes. Where such use is an identification of features or capabilities specified within a standard or for claiming compliance to an IEEE standard, use without explicit approval of IEEE is acceptable, but other use of the terms must be reviewed and approved by the IEEE RAC.

When an EUI is used within the context of an IEEE standard or draft standard, the draft shall be reviewed by the IEEE RAC for correctness and clarity. When an EUI is referenced within non-IEEE standards, the standard developers should contact the IEEE RAC for review of proper usage.

The total number of EUI-48 identifiers available, while large, is NOT inexhaustible. The IEEE RAC has the duty to promote the continued availability of the EUI-48 capability in conjunction with IEEE standards and non-IEEE standards, for the benefit of the world-wide community using those standards.

Initially, EUI-48 identifiers were intended only to identify items of real physical equipment, parts of such equipment, or functions that apply to many instances of physical equipment.

The use of 48-bit identifiers was later extended so that they may serve as protocol identifiers. With this use, they identify protocol designs and design revisions of protocols operating between instances of physical equipment. Compared to quantity of items of physical equipment, far fewer identifiers for such protocols are expected to be needed.

With the exception of such protocol identifiers, EUI-48 identifiers are still intended to identify items of real physical equipment or parts of such equipment, such as separable subsystems or individually addressable network ports. The expected use should not exceed one EUI-48 identifier per hardware subsystem, or at most a very low number of EUI-48 identifiers per physical instance of such equipment (e.g., groups of ports as in IEEE Std 802.1AX, for link aggregation). Allocation of a single EUI-48 identifier to identify or permit addressing of a fixed and permanent function associated with a real item of physical equipment occurs for the lifetime of that equipment or an indefinite period of use.

Any specifications in standards, or assignee implementations or assignee administration of a EUI block, that call for subdivision of the available number space, for block allocation to product types or block allocation to physical equipment without an identifiable physical instance per EUI-48 identifier, or for encoding functional capabilities within significant bits or bit patterns of the identifier, have the potential to rapidly exhaust the address space. To reduce the prospect of exhaustion, new applications and proposed extensions to current applications with significant volume expectations are STRONGLY encouraged to make use of EUI-64, rather than EUI-48, to identify hardware instances. New applications specified in standards that require an address format matching the existing base of EUI-48 equipment will be reviewed by the IEEE RAC and such exceptions will only be approved on a case-by-case basis. Non-standard uses of EUI-48 are not supported.

The IEEE RAC solicits any information about threats to the viability of the unique EUI-48/EUI-64 address space, whether an IEEE proposed standard or another standard or specification. Information should be sent to the IEEE RAC administrator ([email protected]). Furthermore, in carrying out this duty to preserve the longevity of these identifier capabilities, the IEEE RAC will act, via liaison or direct coordination, to prevent potentially abusive uses for the consumption of EUI-48s.

When IEEE 802 began its work in 1980, the target lifetime of EUI-48 identifiers was 100 years. More than a third of the way through that century of lifetime, the use of EUI-48 identifiers continues to grow, with no indication that EUI-48 addresses will be obsolete by 2080. Consequently the IEEE RAC regards the consistent enforcement of these restrictions as a fundamental and realistic basis for ensuring longevity of the EUI-48 identifier.

If an entity, whether an IEEE RA customer or not, has either intentionally or accidentally misused an IEEE RA assignment such that EUI-48/EUI-64 addresses, or any other identifiers that the entity creates from its RA assignment, are allocated outside its assignment(s), then the entity is in violation of IEEE RAC policies. In such cases, the IEEE RAC may recommend the IEEE RA collect additional fees from the entity to remedy any potential duplication and/or discourage future misuse.

Assignees are encouraged to assign only one form of EUI-48 or EUI-64 identifier, regardless of application. In other words, the organization is encouraged to not assign the same identifier to multiple organizations for different end-application uses. The intent of this recommendation is to reduce possible errors introduced by the complexities of managing multiple contextdependent address spaces within  each organization.

For example, EUI-48 values that specify I/O driver software interfaces, language codes, and hardware model numbers should never overlap. Similarly, EUI-64 values that specify I/O driver software interfaces, language codes, hardware model numbers, and hardware instances should never overlap. This no-overlap strategy is expected to reduce unintentional duplication of identifier values, by elimination of subjective application-class judgments, although a few more identifier values may be consumed.

An MA-L assignment includes more than 16 million (2 24 ) unique EUI-48 values. To reduce the occurrences of unused EUI-48s (e.g., when the assignee needs far less than 16 million EUI-48s), the IEEE RAC instituted the following policies for assigning MA-L, MA-M, MA-S, and CID identifiers when the CID was first introduced:

• First-time customers (i.e., assignees) cannot purchase the MA-L. A first-time customer that needs a 24 bit company/organization identifier can purchase a CID, and a first-time customer that needs EUI-48s or EUI-64s (or deprecated identifiers) can purchase an MA-M or MA-S, depending on how many of each particular identifier the customer needs. Exception to this policy must be reviewed by the IEEE RAC.
• The IEEE Registration Authority will accept an additional assignment application upon the certification that at least 95% of the current MA-L or MA-M allocation of EUI-48s is used. The same applies to OUI assignments issued prior to January 2014. An additional assignment may be issued when a significant portion of the existing assignment of EUI-48s has been exhausted. Customers must agree to not produce products using the new assignment of EUI-48s until the previous assignment is fully exhausted. This applies to all registry assignments.
• A customer that has either an MA-L (or, prior to January 1, 2014, an OUI) or CID assignment should not need to purchase a new CID for company identification but is eligible to purchase a new CID for other uses, for example, when a current CID assignment provides insufficient ELI address space.

An IEEE-administered organizational identifier identifies the organization that administers the concatenated extension identifiers to create, for example, EUIs. The IEEE-administered identifier should not be used, in isolation, to identify a division or similar portion of a company or organization. When an assignee feels it necessary to identify such an internal group, the EUI-48 or EUI-64 identifier can be used. (An assignee administration practice that uses some of the extension bits to identify a division or product does not exempt the assignee from the requirement to use the vast majority of the EUI-48 values as described above.) Groups within a standards development organization can similarly be identified by  distinct EUI-48 (or EUI-64) identifiers administered by their sponsoring body.

Mapping an EUI-48 to an EUI-64 is deprecated. The mapping is described here for historical reasons.

Mapping an EUI-48 assigned with an MA-S/OUI-36 or MA-M assignment to an EUI-64 potentially creates a duplicate of an EUI-64 assigned with a different MA-S/OUI-36 or MA-M. The IEEE RA has taken appropriate actions to mitigate creation of duplicates based on this mapping but, to protect the integrity of EUI-64 identifiers, this mapping is deprecated.

Some standards have described how an EUI-48 value could be mapped to an EUI-64, as follows: Let the six octets of the EUI-48 be labeled eui48[0] through eui48[5]. Let the eight octets of the mapped EUI-64 be labeled eui64[0] through eui64[7]. The following mapping has been described:

• eui64[0] = eui48[0]
• eui64[1] = eui48[1]
• eui64[2] = eui48[2]
• eui64[3] = FFhex
• eui64[4] = FEhex or eui64[4] = FFhex
• eui64[5] = eui48[3]
• eui64[6] = eui48[4]
• eui64[7] = eui48[5]

In other words, the EUI-64 value was generated by inserting either the value FF-FEhex or the value FF-FFhex in between eui48[2] and eui48[3].

Some formats of World Wide Names (WWN) are derived from an EUI-48 or EU-64. WWNs are used as disk and endpoint addresses in SCSI and associated protocols. Please refer to latest INCITS SATA and SAS standards for additional details.

IPv6 addressing derived from EUI-64 is defined in IETF RFC 4291, Appendix A. Please see also IETF RFCs 2460, 5952, and 6052.

UUID addressing derived from EUI-64 addresses and OUIs is defined in IETF RFC 4122 in ITU-T X.667.

Just as the OUI is extended to create EUI-48 and EUI-64 identifiers, or a CID can be extended to create a locally administered MAC address, other extended identifiers can be created from an OUI or CID assignment. Such extended identifiers, referred to as context dependent identifiers, are not necessarily globally unique but are intended to only be unique within a well specified context.

A Context Dependent Identifier (CDI) is an extended identifier based on either an OUI, CID, or OUI-36 and typically specified within a standard with additional specification to allow unambiguous interpretation of the identifier and parsing of other data. Some examples include (but are not limited to):

• Defining all fields of the context dependent identifier within a standard. For example, using an OUI or CID to identify a manufacturer of hardware with additional fields identifying the model and revision of the hardware. (The OUI or CID owner typically assigns the values for the additional fields within bounds specified by the standard.) Such an identifier, if properly defined, is unique within the context of the standard.
• Defining vendor-specific extensions to management information within a standard but allowing the assignee of the unique identifier to specify the additional fields. This extended identifier would be unique within the context of the defined management information base.
• A vendor-specific protocol could be identified with an OUI/CID, and a standard defined fixed field to allow identification of multiple protocols from the same vendor; or with the OUI/CID indicating which set of rules to parse the data following the OUI/CID.
• The legacy definition of CDI-32 and CDI-40 (see “Deprecated and Obsolete Identifiers”).

Except where compatibility with legacy definitions of 22-bit company identification is justifiable, the OUI is used as a 24-bit field when creating context dependent identifiers. A CID should serve as an effective alternative to the OUI in such cases. Specifications for context dependent identifiers should allow use of either OUI or CID as the base for the context dependent identifier.

The following cautions are provided for those specifying context dependent identifiers:

• If the context within which the assignment of the extension identifier is required to be unique is not accurately defined, then there is the danger of inadvertent re-use of an existing identifier assignment for a different purpose, leading to ambiguity in the use of the assigned values;
• If the chosen size of the extension identifier is small relative to the actual number of identifier values that will need to be assigned under a single OUI/CID, then the result could be an unacceptable rate of consumption of OUI/CID values, and potential difficulty in the owner of an OUI meeting the Registration Authority's requirement that 95% of the block assignment represented by their existing OUI be consumed before making use of a further assignment.

Consequently, the use of context-dependent identifiers is acceptable, subject to the use meeting all of the following requirements:

• The context within which the context-dependent identifier is used, and within which its identifier values are required to be unique is clearly defined in the relevant standard.
• The size of the chosen extension identifier is large enough to accommodate all conceivable requirements for the allocation of distinct values under a single OUI within the defined context.
• The IEEE RAC has approved the identifier and the definition of the context within which it will be used.
• Draft standards or working group materials that describe a proposed context-dependent identifier and its proposed application should be submitted to the IEEE RAC.

Deprecated and Obsolete Identifiers

There is no standard definition of the term ‘deprecated’ across IEEE. When used by the IEEE RA or IEEE RAC, the term ‘deprecated’ means that the item it is describing (e.g., identifier, mapping, requirement, recommendation, process, etc.) shall not be used in any new applications. Legacy uses may be preserved in a revision or amendment if justified (e.g., so that an amendment does not introduce inconsistency into the standard). When terminology evolves, updates to use the current terms and remove deprecated terms should be done as soon as practical. In addition, new equipment and new designs are not to use the deprecated item, except to remain compliant to the relevant standard. Existing equipment and deployed equipment need not be modified to not use the deprecated item.

Several identifiers and terms used in the past, including some that were created from IEEE-administered identifiers (i.e., created by organizations that were assigned IEEE-administered identifiers), are now deprecated or obsolete. These identifiers and terms include the Individual Address Block (IAB), the 22- bit OUI-based identifiers, the MAC-48 identifier, and the EUI-60. These identifiers are briefly described in the following sub-sections.

IAB-Based Identifiers

The 36-bit IAB identifier is no longer assigned. An IAB assignment was a block of 4096 MAC-48 addresses (now called EUI-48). The base 24-bit OUI is assigned to the IEEE RA and an additional 12-bit extension assigned by the IEEE RA produced the first 36 bits for the block of addresses. The 4096 EUI-48 identifiers were then created by the assignee by a further 12-bits concatenated with the 36-bit IAB base number.

The IAB can be used only for the purpose of assigning EUI-48 identifiers; any other identifiers that might be created by the use of the 24-bit OUI value used to create the IAB remain the property of the IEEE RA. In addition, the IAB cannot be used to create any other identifiers using the 36 bits assigned to the assignee (e.g., the assignee cannot create an EUI-64 by appending 28 bits to the IAB identifier it has been assigned).

While the IEEE RA did not guarantee that the 36-bit IAB identifier would always be created from the same OUI, all IAB assignments were in fact created from two particular OUIs: 00-50-C2hex and 40-D8-55hex. The former was used until all the IABs based on it were assigned, after which the latter was used.

The EUI-48 usage of an IAB and MA-S are the same, so an organization that was assigned an IAB may continue to use it as originally intended. Any new requests made to the IEEE RA for an IAB will be fulfilled by assigning an MA-S.

Going forward, the existing IAB public listing will be maintained as a historical registry. Since no new IABs will be assigned, there will be no additions to the IAB registry.

22-Bit OUI-Based Identifiers

Though the OUI has always been specified as a 24-bit value, a variety of alternative, context-dependent identifiers were specified in the past. Some standards specify use of only 22-bits of the OUI (dropping the M and X bits). Such uses are deprecated. All new specifications for use of an OUI, except for networking addressing, shall use all 24-bits of the OUI as assigned by the IEEE RA. This allows use of either an OUI or CID.

The term MAC-48 is now obsolete. The MAC-48 was similar to the EUI-48, i.e., it was a concatenation of a 24-bit OUI assigned by the IEEE RA and a 24-bit extension identifier assigned by the organization with that OUI assignment. However, it was used to address hardware interfaces within existing 802- based networking applications. The term EUI-48 was historically used to identify a design instance, as opposed to a hardware interface; examples include software interface standards (such as VGA), the model number for a product, and the form/function of vendor-specific content. The subtle difference between MAC-48 and EUI-48 was not well understood, so the term EUI-48 is now used for both uses, and the term MAC-48 identifier is now obsolete. (The IEEE RAC is not aware of any cases, but if MAC-48 is used as the name for any 48-bit MAC address, then EUI-48 is not the appropriate replacement term for MAC-48, as EUI-48 only refers to individual, universally/globally unique network addresses.)

The EUI-60 should not be used in future applications. There is no plan to eliminate the use of these EUI-60 values in the foreseeable future. EUI-64 (as opposed to EUI-60) identifiers should be used in future applications, future standards, and revisions and amendments of existing standards requiring the use of unique per-hardware instance identifiers.

CDI-32 and CDI-40

CDI-32 and CDI-40 were historically recommended as context dependent identifiers.

CDI-32 was, historically, a concatenation of an OUI value assigned by the IEEE RA and an 8-bit extension identifier assigned by the organization with that OUI assignment.

CDI-40 was, historically, a concatenation of an OUI value assigned by the IEEE RA and a 16-bit extension identifier assigned by the organization with that OUI assignment.

The IEEE Registration Authority makes a concerted effort to avoid duplicate assignments but does not guarantee that duplicate assignments have not occurred. Global uniqueness also depends on proper use of assignments and absence of faults that might result in duplication.

This example octet string could be in use and is not a reserved value.

The IEEE RA public listing provides separate databases for MA-L, MA-M, and MA-S. If the first 24 bits match an OUI assigned to the IEEE RA, then a search of the first 28 or 36 bits may reveal an MA-M or MA-S assignment. If the OUI-36 is not found in an MA-S search, then a search of the first 24 or 28 bits may reveal an MA-L or MA-M assignment from which the OUI-36 has been created from a member of the assigned block.

Related articles

• MAC address options
• Registration Authority Payments
• MA-S Qty/Price
• Company name not on the Registration Authority public listing
• MA-L Qty/Price

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What are the possible OUIs for the Ethernet MAC address?

I'm setting up a computer lab in which many Raspberry Pis are going to acquire IP addresses via DHCP. I'd like to have the DHCP server to differentiate between Raspberry Pis and other clients.

What are the organizationally unique identifiers (OUIs) for the Ethernet cards on Raspberry Pis with which I might discriminate Raspberry Pis from other DHCP clients?

(I am aware that MAC addresses can be spoofed and am assuming that the DHCP clients are not hostile.)

• ethernet-port

11 Answers 11

"current" data for raspberry pi devices:, ma-l/oui mac address prefixes: 6.

MA-L: Mac Address Block Large (previously named OUI). Number of address 2^24 (~16 Million)

CID prefix: 1

CID: Company Identifier. This prefix will not be used for globally unique applications. Number of address 2^24 (~16 Million)

Sources: https://maclookup.app/vendors/raspberry-pi-trading-ltd https://maclookup.app/vendors/raspberry-pi-foundation https://regauth.standards.ieee.org/standards-ra-web/pub/view.html#registries

FYI, my Pico W has a 28:CD:C1 address.

You can fetch the most up to date MA-L data from the IEEE with this one-liner:

You can fetch the most up to date CID data from the IEEE with this one-liner:

• 1 As of 4 January 2024 both the 28:CD:C1 and D8:3A:DD are now registered to Raspberry Pi Trading Ltd, per the IEEE OUI database. –  devstuff Commented Jan 4 at 17:55
• 1 3A:35:41 is a CID (Company ID) maclookup.app/macaddress/3a3541 –  devstuff Commented Jan 4 at 18:25

The best resource to find the most current OUI assignments is from the MAC Address Block Large (MA-L) Public Listing at the IEEE -- http://standards.ieee.org/develop/regauth/oui/public.html .

A complete list of OUI assignments is compiled daily and is available at http://standards-oui.ieee.org/oui.txt .

According to this list there is a single OUI/MA-L assignment for the Raspberry Pi Foundation:

• 1 I can confirm it's still B8-27-EB on a Raspberry Pi 3 Model B –  Eugen Commented Aug 11, 2017 at 19:40

To elaborate the answer from @cachius: the OUI has changed from

according to http://standards-oui.ieee.org/oui.txt .

The Raspberry Pi 4 Model B already has the new OUI.

• Why did it change? –  james-see Commented Nov 19, 2019 at 17:28
• @jamescampbell I don't know. I guess because the company has changed. The first bytes of a mac address are the companiy id. –  Ingo Commented Nov 19, 2019 at 18:13
• 1 @jamescampbell: I don't know precisely why the company changed, but FYI, the original OUI was registered to the Raspberry Pi Foundation - a "registered charity" in the UK. UK laws govern finances of charities, and of course charities are not permitted to make a "profit". Here's a thumbnail sketch of their finances. It seems a reasonable guess that money is behind the decision, more specically how it is accounted for and distributed. –  Seamus Commented Dec 7, 2019 at 19:20
• 2 @james-see: Each prefix allows for 16 million MAC addresses, so if they didn't want to re-use them (since that would make it harder for them to coexist on the same network) they would need a new prefix. As of 2022, 40 million units had been sold, so after 16 million they'd need the first change, after 32 million the next, and so on. With WiFi needing more addresses and Pico-W using more too, they need a lot more prefixes if they want to avoid re-issuing the same addresses. –  Malvineous Commented Jan 13 at 16:55
• 1 Wow. 🤯 @Malvineous thank you! That makes sense! –  james-see Commented Jan 14 at 18:40

According to the wikipedia article you linked,

In MAC addresses, the OUI is combined with a 24-bit number (assigned by the owner or 'assignee' of the OUI) to form the address. The first three octets of the address are the OUI.

So this is pretty straightforward; the first half of a MAC address is the OUI and the second half is arbitrary.

Lo and behold, on the four pis I have here (two B's, one made in China, one B+, and one pi 2), the first three octets are:

Doing a bit of random searching online ("raspberry pi MAC address") also turns up this OUI.

The below script can be used to find any vendor by Mac: Raspberry Pi or otherwise.

Just supply the vendor's name as it's specified in the IEEE's MAC DB:

" http://standards-oui.ieee.org/oui.txt "

in the variable "VENDOR" and of course replace the echo's in the conditional expression with something useful.

In its' present form it's meant to execute locally on a host, but the script could be adapted quite easily I imagine.

It is worth noticing, that the companyname (in the oui.txt) changed with the new Pi4:

• B8-27-EB (hex) Raspberry Pi Foundation
• DC-A6-32 (hex) Raspberry Pi Trading Ltd.

• Thanks for the script! I edited it to still work with the different Raspberry company names that came with the Pi 4. –  Stefan Wegener Commented Oct 7, 2019 at 12:15
• @StefanWegener Sooper-dooper! Thanks for helping keep answers current! –  F1Linux Commented Oct 7, 2019 at 12:18
• For an online search, regauth.standards.ieee.org has the most up-to-date data. Choose the "All MAC" product. –  devstuff Commented Jan 4 at 18:01
• standards.ieee.org/products-programs/regauth offers links to download MAC assignment lists for the large, medium and small ranges. RPi is only in the MA-L list but a general search script would need to download all 3 files. NOTE: the links on the page are currently rendered as http:// but the equivalent https:// links work fine. –  devstuff Commented Jan 4 at 18:15

It is worth noting that the MAC-48 number applies to the Network Interface and not the Host device and thus the B8:27:EB applies only to the wired EtherNet interface on older Raspberry Pi devices that do not have a built-in Broadcomm device providing Wireless networking!

A WiFi USB dongle added to give an RPi wireless-networking where it does not have it natively will have a OUI that is specific (one hopes) to the manufacturer - though there are now utilities to fake the whole MAC number for good (or evil) purposes. This is important should you be trying to find older RPis wirelessly and wondering why you cannot see MACs beginning with that value...

To add to what @Ingo said, they actually have a third OUI now: E4-5F-01

Not sure why that happened either, but I have hardware with a MAC with that OUI.

I'd have commented that, but don't have enough reputation.

• That is not registered to anyone as far as I can see. adminsub.net/mac-address-finder/E45F01 –  david collier Commented Aug 5, 2022 at 10:32
• @davidcollier The tool you used is out of date. This one finds it: maclookup.app/macaddress/E45F01 –  Adam Howell Commented Nov 28, 2022 at 18:13

In my very personal case.

Find Results B8:27:EB Raspberry Pi Foundation

Both the Ethernet and the Wifi on the RPi3 (Raspberry Pi 3) have are prefixed b8:27:eb .

The Raspberry Pi 4 has

according to the Raspberry Pi Forums .

confirming a reception of an rpi in the mac range D8:3A:DD , with 4GB RAM.

cannot upvote yet, otherwise I would have done that instead.

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OUI and MAC address lookup

Mac oui lookup tool.

Unveiling the Power of MAC OUI Lookup Tools: Deciphering the Origins of Networked Devices

In the intricate landscape of networking, the MAC (Media Access Control) address serves as a unique identifier for devices, allowing them to communicate within local networks. At the heart of understanding and unraveling the origins of these identifiers lies the MAC OUI (Organizationally Unique Identifier) Lookup tool. In this comprehensive exploration, we delve into the significance of MAC OUI Lookup tools, how they operate, and the valuable insights they provide about the diverse array of devices that populate our interconnected world.

Understanding MAC Addresses and OUI: Foundation of Device Identification

Before delving into the specifics of MAC OUI Lookup tools, it’s crucial to establish a foundational understanding of MAC addresses and the OUI within them, forming the building blocks of device identification.

• MAC Addresses as Identifiers: MAC addresses, typically 48 bits in length, are assigned to network interface cards (NICs) or network adapters. They play a pivotal role in facilitating communication within local networks.
• Organizationally Unique Identifier (OUI): The first 24 bits (the first three octets) of a MAC address constitute the OUI. This segment is assigned by the IEEE (Institute of Electrical and Electronics Engineers) and uniquely identifies the manufacturer or organization responsible for the device’s network interface.
• Digital Fingerprint: The OUI acts as a digital fingerprint, enabling network administrators, security professionals, and enthusiasts to trace the origins of networked devices back to their manufacturers.

The Significance of MAC OUI Lookup Tools: Decoding Device Origins

MAC OUI Lookup tools stand as powerful instruments for decoding the OUI within MAC addresses, unveiling essential information about the manufacturer or organization behind each networked device. Understanding the significance of MAC OUI Lookup tools provides insights into the origins of devices within interconnected networks.

• Device Identification: MAC OUI Lookup tools enable swift identification of the manufacturer or organization associated with a specific device’s MAC address. This information is particularly valuable for network administrators seeking to understand the composition of their networks.
• Inventory Management: In large-scale networks and enterprise environments, MAC OUI Lookup tools aid in efficient inventory management. They allow administrators to quickly ascertain the manufacturers of devices connected to the network, facilitating asset tracking and organization.
• Security Enhancement: The capability to identify device manufacturers through MAC OUI Lookup contributes to network security. Administrators can swiftly detect unauthorized devices or those from unknown manufacturers, assisting in the detection and mitigation of potential security threats.
• Device Troubleshooting: When troubleshooting network issues, MAC OUI Lookup tools provide an additional layer of information. Knowing the manufacturer of a device can aid in diagnosing problems related to specific hardware models or configurations.
• Compliance and Policies: Organizations often have policies or compliance requirements regarding the types of devices permitted on their networks. MAC OUI Lookup tools support the enforcement of these policies by identifying the manufacturers of connected devices.

How MAC OUI Lookup Tools Work: Navigating Device Identification

MAC OUI Lookup tools operate by deciphering the OUI portion of a MAC address and associating it with the manufacturer or organization responsible for the device’s network interface. The process involves several key steps:

• OUI Extraction: The first 24 bits of a MAC address, representing the OUI, are extracted. This isolates the unique identifier associated with the device’s manufacturer.
• Database Query: The extracted OUI is queried against databases containing mappings between OUIs and manufacturers. These databases are typically maintained and updated by organizations such as the IEEE.
• Manufacturer Identification: The queried OUI is matched to entries in the database, revealing the manufacturer or organization associated with that specific portion of the MAC address.
• Information Display: MAC OUI Lookup tools then display detailed information about the manufacturer, which may include the company name, address, and additional details. This information offers valuable insights into the origins of the networked device.
• User Interface: MAC OUI Lookup tools often provide user-friendly interfaces, allowing users to input or paste MAC addresses for quick identification. Some tools also offer APIs for programmatic access to OUI information.

Diversity in MAC OUIs: A Global Tapestry of Manufacturers

The landscape of MAC OUIs is characterized by a rich diversity of manufacturers, each assigned a unique identifier reflecting its role in the realm of networking hardware. Manufacturers span the spectrum from industry giants to specialized players, contributing to the intricate mosaic of networked devices.

• Industry Leaders: Prominent technology companies, including household names such as Apple, Microsoft, and Cisco, each possess distinct MAC OUIs reflecting their significant role in shaping the landscape of networking technology.
• Specialized Manufacturers: Beyond well-known entities, specialized manufacturers catering to specific niches contribute to the diversity of MAC OUIs. These may include manufacturers of industrial IoT devices, medical equipment, or components for specific industries.
• Global Representation: MAC OUIs are assigned globally, representing manufacturers from various countries and regions. This global distribution emphasizes the interconnected nature of the modern world, where devices from diverse origins contribute to the fabric of networks.

Implications for Networked Environments: Enhancing Visibility and Control

The application of MAC OUI Lookup tools within networked environments carries significant implications for visibility, control, and the overall management of interconnected devices.

• Network Visibility: MAC OUI Lookup tools enhance network visibility by providing administrators with detailed insights into the types of devices connected to their networks. This information extends beyond IP addresses, offering a more comprehensive view of the hardware ecosystem.
• Device Classification: Knowing the manufacturer of devices enables administrators to classify and categorize devices based on their hardware origins. This classification aids in creating device inventories and implementing policies based on device types.
• Security Policies: MAC OUI Lookup tools support the implementation of security policies by enabling administrators to identify and manage devices from specific manufacturers. This can be crucial in enforcing access controls and preventing the entry of unauthorized devices.
• Resource Allocation: In environments where resource allocation is critical, such as in enterprise networks, MAC OUI Lookup tools assist in optimizing resource allocation by identifying the types of devices that require specific network resources.
• Forensic Analysis: In the event of security incidents or anomalies, MAC OUI Lookup tools can be valuable for forensic analysis. Identifying the manufacturers of devices involved in security events helps in understanding the nature of incidents and planning appropriate responses.

Privacy Considerations in MAC OUI Lookup: Balancing Information and Anonymity

While MAC OUI Lookup tools provide valuable information about device manufacturers, they also raise privacy considerations. Striking a balance between gaining insights into networked environments and preserving user privacy is essential.

• Anonymous MAC Addresses: Some devices, particularly those designed with privacy in mind, may use randomized or anonymous MAC addresses. MAC OUI Lookup tools should be aware of this practice and its implications for accurate device identification.
• Ethical Use: Users and administrators employing MAC OUI Lookup tools should do so ethically and responsibly. Avoiding the misuse of information and respecting privacy rights is paramount.
• User Consent: In scenarios where MAC addresses are linked to user identities, obtaining user consent for the collection and use of such information is crucial. Transparency in data practices fosters trust in networked environments.

Conclusion: Navigating the World of MAC OUI Lookup Tools

In the dynamic and interconnected world of networking, MAC OUI Lookup tools emerge as indispensable instruments for unraveling the origins of networked devices. From providing real-time insights and enhancing security to aiding in troubleshooting and compliance, these tools contribute significantly to the effective management of networked environments.

As networked ecosystems continue to evolve, fueled by innovation and connectivity, the responsible use of MAC OUI Lookup tools becomes paramount. By understanding the manufacturers behind the devices that populate our networks, administrators, security professionals, and enthusiasts can navigate the complexities of networking with precision, ensuring a resilient and secure digital ecosystem. In conclusion, MAC OUI Lookup tools serve not only as technical utilities but as keys unlocking the doors to the diverse and fascinating world of networked identities within the expansive realm of network communication.

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An In-Depth Guide to Understanding MAC Addresses

• riazul-islam
• September 6, 2024

Table of Contents

Dear reader, addressing schemes form the fundamental basis for communication on computer networks. Of these, Media Access Control (MAC) addresses operate at layer 2, making communication possible between devices on the same local area network (LAN). This guide provides an extensive look at what MAC addresses are and how they work.

What is a MAC Address?

A MAC address uniquely identifies any device or network interface controller (NIC) on an Ethernet LAN. It is a 48-bit hardware address usually represented as 12 hexadecimal characters. For example: 01-23-45-67-89-AB

MAC addresses enable data packets to be transmitted between devices on the same network segment. They operate at the data link layer (layer 2) of the OSI model.

Technical Specifications

The 48 bits that make up a MAC address consist of the following:

• Bits 40-47 – Unique serial number assigned by the manufacturer
• Bits 24-39 – Manufacturer‘s ID assigned by IEEE
• Bits 0-23 – Extension identifier for specific NICs

The large 24-bit block assigned to each manufacturer ensures global uniqueness. There are over 281 trillion possible MAC addresses!

Now the newer EUI-64 specification uses a 64-bit address space allowing for even more addresses.

Allocation and Assignment

The Institute of Electrical and Electronics Engineers (IEEE) is responsible for assigning unique Organizationally Unique Identifiers (OUIs) to companies and organizations.

As of 2022, over 40,000 OUIs have been allocated. Manufacturers embed their OUI into every NIC they produce, appending the serial number to create the complete MAC address.

Packet Forwarding Using MAC Addresses

When any packet is transmitted on an Ethernet LAN, the sender already knows the MAC address of the destination device. This is determined using the Address Resolution Protocol (ARP).

The flow of traffic based on MAC addresses is:

• Source device sends an ARP request asking "Who has this IP address?"
• Destination device replies with its MAC address
• Actual packet transmission starts using source & destination MAC addresses

Switches also maintain MAC address tables to forward frames only to destination ports. This ensures efficient traffic flow.

Security and Privacy Considerations

While MAC addresses enable effective LAN communication, there are certain risks:

• MAC addresses can be spoofed and falsified, allowing attackers to bypass access controls
• MAC addresses linked to personal devices can reveal sensitive location and behavior analytics when snooped

Network administrators often employ MAC address security using DHCP filters, port security and static NAT mapping to minimize attack surfaces.

There is also the ethical dilemma regarding privacy violations from tracking MAC addresses without consent. Users often manually change MAC addresses to prevent this.

I hope this guide gave you a detailed overview explaining what MAC addresses are, how they are assigned, their role in networking, as well as security considerations. Understanding the layer 2 addressing scheme is key to troubleshooting connectivity issues and strengthening network foundations.

Please reach out in case any part of this MAC address reference needs clarification! I would be glad to discuss it further.

• hacking , network

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Standards Group MAC Address

Standard group mac address.

For Standards Development Use Only

A Universally Administered Address Block has been allocated for the assignment of Group MAC Addresses for use in Standards.

The Standard Group MAC Address assignment is a universally administered address block for use in standards by standards developers . If you require MAC Addresses for your products, please refer to the information on purchasing and using an MA-L , MA-M or MA-S assignment to create MAC Addresses for your products.

Registration Fees

Application Information

• Complete and submit the Standard Group MAC Address Application (PDF) . Attach an explanatory statement detailing the intended use of the assignment. Applications expire after 30 days.
• Any questions regarding your application will be sent via email to the REQUESTOR.
• Applications are reviewed within 150 days. Additional clarification may be required by our review committee.
• Once approved, the application will be processed within 7 business days. Assignment details are sent to the REQUESTOR.

Related Standards

All MAC protocol data units contain addressing information that consists of two fields: the destination MAC address and the source MAC address. Both of these address fields are 48-bit fields; the structure and semantics of the address fields are defined in ISO/IEC 10039.

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MAC Address Lookup

Find the vendor name of a device by entering an OUI or a MAC address

snom technology GmbH

OUI : 00:04:13

Vendor name : snom technology GmbH

Aroser Allee 66 Berlin 13407 DE.

Mac Address Block Large (previously named OUI). Number of address 2^24 (~16 Million)

Last updated : 23 August 2023

Initial registration : 09 November 2000