Sep 24, 2018 The MAC address (short for media access control address) is the worldwide unique hardware address of a single network adapter. The physical address is used to identify a device in computer networks. Since MAC addresses are assigned directly by the hardware manufacturer, they are also referred to as hardware addresses.
The hardware address is also known as the data link layer address or layer 2 address or MAC (Media Access Control) address. From these terms, the term MAC address is commonly used to refer to the hardware address. Unlike the IP address or software address, this address can’t be.
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If the IP address belongs to another subnet, the layer two frames address to the MAC address of the responsible router (usually the default gateway). The router is responsible for switching the packet to the next network node or the destination computer and also sends it on the following network section to a MAC address.
Every network adapter has a Media Access Control address (usuallyshortened to MAC address). A MAC address is a six-byte identifyingnumber permanently embedded in the firmware of the adapter,and is readable by the network and the operating system of the deviceon which the adapter is installed. All Ethernet cards andmodems have a MAC address. The address must follow the standards setby the Institute of Electrical and Electronics Engineers(IEEE), which sets computer networking standards. The MACaddress is a six-pair set of hexadecimal numbers, forexample, a1-c2-e3-44-5f-6d.
The purpose of the MAC address is to uniquely identify every node(e.g., workstations and printers) on a network. Every adapter has aunique MAC address. Even two identical models from the samemanufacturer will have distinct MAC addresses.
Note: You may also hear people refer to the MACaddress as the physical address, the hardware address, or the adapteraddress.
To find the MAC address for smartphones and other mobile devices,see ARCHIVED: At IU, how do I register my smartphone or mobile device on thenetwork?
To find the MAC address for desktop and other devices, see theappropriate document below:
How would you communicate with a device when you don’t have the IP?
You might be in a situation where you don’t have the IP address of a device in a local network, but all you have is records of the MAC or hardware address.
Or your computer is unable to display its IP due to various reasons, and you are getting a “No Valid IP Address” error.
Finding the IP from a known MAC address should be the task of a ReverseARP application, the counterpart of ARP.
But RARP is an obsolete protocol with many disadvantages, so it was quickly replaced by other protocols like BOOTP and DHCP, which deal directly with IP addresses.
In this article, we’ll show you how to find IPs and device vendors using MAC addresses with different methods for free.
Understanding ARP
ARP (Address Resolution Protocol) is the protocol in charge of finding MAC addresses with IPs in local network segments. Bulk mail software for mac.
It operates with frames on the data link layer.
As you might already know, devices in the data link layer depend on MAC addresses for their communication.
Their frames encapsulate packets that contain IP address information.
A device must know the destination MAC address to communicate locally through media types like Ethernet or Wifi, in layer 2 of the OSI model.
Understanding how ARP works can help you find IPs and MAC addresses quickly.
The following message flow diagram can help you understand the concept:
The local computer sends a ping (ICMP echo request) to a destination IP address (remote computer) within the same segment. Unfortunately, the local computer does not know the MAC address… it only knows the IP address.
The destination hardware address is unknown, so the ICMP echo request is put on hold. The local computer only knows its source/destination IP and its source MAC addresses. ARP uses two types of messages, ARP Request and Reply.
The local computer sends an ARP REQUEST message to find the owner of the IP address in question.
This message is sent to all devices within the same segment or LAN through a broadcast MAC (FF:FF:FF:FF:FF:FF) as the destination.
Because the remote computer is part of the same network segment, it receives the broadcast message sent by the local computer. All other computers in the LAN also receive the broadcast but they know that the destination IP is not theirs, so they discard the packet. Only the remote computer with destination IP, responds to the ARP REQUEST with an ARP REPLY, which contains the target MAC address.
The local computer receives the ARP REPLY with the MAC address. It then resumes the ICMP echo request, and finally, the remote computer responds with an ICMP echo reply.
Finding IPs with ARP
You can use ARP to obtain an IP from a known MAC address.
But first, it is important to update your local ARP table in order to get information from all devices in the network.
Send a ping (ICMP echo reply) to the entire LAN, to get all the MAC entries on the table.
To ping the entire LAN, you can send a broadcast to your network.
Open the Command Prompt in Windows or terminal in macOS and type.
ping 192.168.0.255
My subnet is 192.168.0.0/24 (mask of 255.255.255.0), so the broadcast address is 192.168.0.255 which can be calculated or found with a “Print Route” command in Windows or a “netstat -nr” in macOS. Or can also be obtained with a subnet calculator.
For Windows:
Step 1.
Open the CMD (Command Prompt)
Go to the “Start” menu and select “Run” or press (Windows key + R) to open the Run application
In the “Open” textbox type “cmd” and press “Ok”.
This will open the command-line interface in Windows.
Step 2.
Enter the “arp” command.
The arp command without any additional arguments will give you a list of options that you can use.
Step 3.
Use the arp with additional arguments to find the IP within the same network segment.
With the command “arp -a” you can see the ARP table and its entries recently populated by your computer with the broadcast ping.
Step 4.
Reading the output.
The information displayed in the arp-a is basically the ARP table on your computer.
It shows a list with IP addresses, their corresponding physical address (or MAC), and the type of allocation (dynamic or static).
Let’s say you have the MAC address 60-30-d4-76-b8-c8 (which is a macOS device) and you want to know the IP.
From the results shown above, you can map the MAC address to the IP address in the same line.
The IP Address is 192.168.0.102 (which is in the same network segment) belongs to 60-30-d4-76-b8-c8.
You can forget about those 224.0.0.x and 239.0.0.x addresses, as they are multicast IPs.
For macOS:
Step 1:
Open the Terminal App. go to Applications > Utilities > Terminal or Launchpad > Other > Terminal.
Step 2:
Enter the “arp” command with an “-a” flag.
Once you enter the command “arp -a” you’ll receive a list with all ARP entries to the ARP Table in your computer.
The output will show a line with the IP address followed by the MAC address, the interface, and the allocation type (dynamic/static).
Finding IPs with the DHCP Server
The Dynamic Host Configuration Protocol (DHCP) is the network protocol used by TCP/IP to dynamically allocate IP addresses and other characteristics to devices in a network.
The DHCP works with a client/server mode.
The DHCP server is the device in charge of assigning IP addresses in a network, and the client is usually your computer.
For home networks or LANs, the DHCP Server is typically a router or gateway.
Akai professional mpc studio drum machine. If you have access to the DHCP Server, you can view all relationships with IPs, MACs, interfaces, name of the device, and lease time in your LAN.
Step 1.
Log into the DHCP Server. In this example, the DHCP server is the home gateway.
If you don’t know the IP address of your DHCP Server/ Gateway, you can run an ipconfig (in Windows) or ifconfig (in macOS/Linux).
This particular DHCP Server/Gateway has a web interface.
Step 2.
Enter the IP address on the search bar of the web browser, and input the right credentials.
Step 3.
Find the DHCP Clients List.
In this TP-Link router, the DHCP Server functionality comes as an additional feature.
Go to DHCP > DHCP Clients List. From this list, you can see the mapping between MAC addresses and their assigned IPs.
Using Sniffers
If you couldn’t find the IP in the ARP list or unfortunately don’t have access to the DHCP Server, as a last resort, you can use a sniffer.
Packet sniffers or network analyzers like Nmap (or Zenmap which is the GUI version) are designed for network security.
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They can help identify attacks and vulnerabilities in the network.
With Nmap, you can actively scan your entire network and find IPs, ports, protocols, MACs, etc.
If you are trying to find the IP from a known MAC with a sniffer like Nmap, look for the MAC address within the scan results.
How to find the Device and IP with a Sniffer?
Step 1.
Keep records of your network IP address information.
In this case, my network IP is 192.168.0.0/24. If you don’t know it, a quick “ipconfig” in Windows cmd or an “ifconfig” in macOS or Linux terminal can show you the local IP and mask.
If you can’t subnet, go online to a subnet calculator and find your network IP.
Step 2.
Download and open Nmap.
Download Nmap from this official link https://nmap.org/download.html and follow its straightforward installation process.
Step 3.
Open Nmap (or Zenmap) and use the command “sudo nmap -sn (network IP)” to scan the entire network (without port scan).
The command will list machines that respond to the Ping and will include their MAC address along with the vendor.
Don’t forget the “sudo” command.
Without it, you will not see MAC addresses.
Finding out the device vendor from a MAC address
Ok, so now you were able to find out the IP address using “arp -a” command or through the DHCP Server.
But what if you want to know more details about that particular device?
What vendor is it?
Your network segment or LAN might be full of different devices, from computers, firewalls, routers, mobiles, printers, TVs, etc.
And MAC addresses contain key information for knowing more details about each network device.
First, it is essential to understand the format of the MAC address.
Traditional MAC addresses are 48 bits represented in 12-digit hexadecimal numbers (or six octets).
The first half of the six octets represent the Organizational Unique Identifier (OUI) and the other half is the Network Interface Controller (NIC) which is unique for every device in the world.
There is not much we can do about the NIC, other than communicating with it.
Free mac apps downloads. But the OUI can give us useful information about the vendor if you didn’t use Nmap, which can also give you the hardware vendor.
Mac Address Hardware Or Software Reviews
A free online OUI lookup tool like Wireshark OUI Lookup can help you with this.
Just enter the MAC address on the OUI search, and the tool will look at the first three octets and correlate with its manufacturing database.
Final Words
Although the RARP (the counterpart of ARP) was specifically designed to find IPs from MAC addresses, it was quickly discontinued because it had many drawbacks.