• Show Mac Address For Ip
• Find Ip Address Mac Address Cisco Switch
• Find Ip Address Using Mac Address

On the layer 2 device (switch) enter the username and password if needed. Next enter 'enable' mode on the switch by typing enable. Next type the command 'show mac address-table'. If successful it should.

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• I have the IP address and I and trying to find the mac address or interface that connected to the server. Could you tell me the command or the way to find the Switch port or mac address if you only have ip address. Regards Star 0 Helpful Reply. Patrick Harrold. Beginner In response to Star.
• In System Preferences, click View menu and select Network In the Network window that just opened, click the Wi-Fi, Ethernet, or Airport icon on left. Now click Advanced on bottom right. From the upper menu, click Hardware, and look for MAC Address field.
• A media access control address (MAC address), unique identifier for your device connecting to a network, sometimes called physicall address. An Internet Protocol address (IP Address), is a unique string of numbers separated by periods that identifies each computer over a network. You will need to know how to obtain your MAC address to register a device on the wired network at FIT Residence.

How to find an IP address when you have the MAC address of the device.

4 Steps total

Step 1: Open the command prompt

Click the Windows 'Start' button and select 'Run.' In the textbox, type 'cmd' and click the 'Ok' button. This opens a DOS prompt.

Step 2: Familiarize yourself with arp

Type 'arp' in the command prompt. This gives you a list of options to use with the arp command.

Step 3: List all MAC addresses

Type 'arp -a' in the command prompt. This lists a number of MAC addresses with the associated IP addresses. Since you have the MAC address, scroll down the list to find the associated IP address. The MAC address is shown in the 'Physical Address' column with the IP address in the 'Internet Address' column. An example of a table record is in Step 4.

Step 4: Evaluate results

The following is an example of ARP output. The first column is the IP address. The second column is the MAC address, and the third is the type of IP assigned--static or dynamic.

Internet address Physical Address Type

192.168.0.1 01-a3-56-b5-ff-22 static

References

• How to Use a MAC Address to Find an IP Address

16 Comments

• Datil
  Krizz Jan 21, 2013 at 10:36pm

  You've forgotten about one little thing: arp keeps mac<>ip association of recently contacted peers, so it's quite often not to find the mac<>ip association we're looking for, of machine that exists in the network. Prior to using arp -a it's wise to ping the host first.

• Habanero
  Twon of An Jan 21, 2013 at 11:24pm

  Used in conjunction with ping (thanks Krizz), this is a good basic walk through. I can't go wrong with these steps!

• Cayenne
  Syldra Jan 22, 2013 at 03:17pm

  I'm sorry but.. if the thing is to find the IP address from the MAC, how will you ping the host first ?

• Serrano
  Enzeder Jan 22, 2013 at 04:37pm

  I thought the aim of this exercise was to FIND an IP address. Doesn't using PING imply you already know the IP (or hostname) which makes ARP redundant? How do you PING a MAC?

  Assuming no IP or hostname info, I have used a portscanner (like LanSpy or Zenmap) to get MAC > IP info. Currently my preferred method if the device isn't listed in Spiceworks :-)

  There was a time when I was a baby admin and I didn't want to raise alarms by installing a scanner that I wrote a batch file (yes, that long ago) that PINGed every IP on a subnet, then immediately ran ARP redirecting output to a text file. But that depends on the device in question being set to respond to PING requests.

• Pimiento
  christian.mcghee Dec 23, 2013 at 03:47am

  This does not work for any host on the other side of a router. Any hosts on the other side of the router will show the routers MAC address.

• Serrano
  @Greg Mar 11, 2014 at 03:11pm

  I realize this is an old topic, but someone like myself may be looking for an answer. I became admin of a network with little over 200 devices, which none of the cabling was mapped. I was told I was responsible for the cabling, so I began looking for a way other than toning out all the cables. I was fortunate to have Cisco switches and Windows Server 2008. I was able to use the Cisco Network Assistant to grab MAC addresses and the port number, then in DHCP on the Server 2008 I could find the MAC and corresponding IP. Furthermore I could also get the computer name from DHCP and correlate that to which user was on the machine using PDQ inventory to see who was logged in to the machine. Most of this of course depends on the devices being in use. I've been able to create an accurate map of about 90% of my network without touching the cables.

• Pimiento
  christopherblouch Jun 4, 2014 at 05:08pm

  I am interested in this thread, hopefully someone can help. There are 4 types of arp message: arp request, arp reply, rarp request, rarp reply. So, that being said, is it possible to manually send a rarp request? Sort of a arp based ping?There is arping, but we need rarping.. if it exists. Of course, I understand that I can't arp outside my default gateway, but if there is a rarp request, how is it used inside the local network? Thanks to whatever guru can explain what we're missing.

• Serrano
  Maxwell Brotherwood Jul 18, 2014 at 10:07am

  Great for finding an IP if you have the MAC address.

  My instance where I found this useful was after updating the firmware on a switch remotely via TFTP, the IP of the switch would change (making pinging redundant, obviously). Trying a network scan over Spiceworks or rescanning the single device would not update the IP and I needed an alternate way to find it.

  This method worked perfectly. Thank you. Hopefully this helps those trying to understand the purpose of this practice and how it was in-fact useful.

• Pimiento
  robertrobinson2 Aug 4, 2014 at 04:30pm

  I understand the issues in attempting to use a MAC address to locate a device from outside of its local network.
  What puzzles me is how Honeywell Total Connect does this with their WiFi connected thermostats. The hardware configuration is: a Honeywell WiFi thermostat that is WiFi connected to a Netgear N600 router which uses DHCP to assign an IP adddress. The router is connected to Comcast with a Motorola SB6120 modem. Comcast assigns a system wide (dynamic) IP. There is no static IP.
  On initial setup, a WiFi connection is first established between the thermostat and the router. The thermostat's MAC and CRC and a username and password are entered into the Total Connect software setup. It is then possible to read or set thermostat values using Total Connect Web pages.
  I know how to do this with a static IP or a DNS service that automatically tracks changes in dynamic IP addresses.
  Does anyone understand how this works with Total Connect?

• Tabasco
  Joe979 Sep 4, 2014 at 01:05pm

  This post was extremely helpful, thanks itdownsouth :) I used show interface to find MAC addresses on our switches (reason for this is poor network documentation and mis-labeled switchports and wall jacks..). I took the MAC addresses that I could not locate the hosts or ip addresses for, ran arp -a to list the address<>mac list, then one by one, nbtstat -A for each IP address I matched a MAC to from the unlabeled ports. Tedious, but found 5 or 6 now (seeing hexadecimal thoughts now though..).

• Tabasco
  Joe979 Sep 4, 2014 at 01:12pm

  By the way, the reason this is working great for me is the lack of routers -- all switches, so if you have only one subnet like we do, this will do -- otherwise, you will probably need to login to the router or switch on the other side of the router to find MAC address tables on the other networks. You may not be able to see them all on the local host, as far as arp -a on the local host, but looking up the arp or hosts tables on switches and routers could be a possible solution for those with multiple subnets.

• Jalapeno
  Jay196 Oct 21, 2014 at 03:28pm

  Use SuperScan to do a bulk ping of the entire network range. SuperScan 3 (I recommend) is a free tool by McAfee.

  Then use arp -a | Find '5c-d9-98' to get for example all ping nodes with a manufacturer of Asus.

• Datil
  WealthyEmu Mar 25, 2015 at 07:55pm

  There's also this:

  http://www.advanced-ip-scanner.com/

  It should be able to find most devices on the network. You can specify the range to scan and scan across subnets. I won't try to share all the features because quite frankly I don't know them all.

• Pimiento
  amiruli Jul 4, 2015 at 10:18am

  If you want you can ping the broadcast address to ping everyone on the network then do arp -a

• Pimiento
  chrisdahlkvist Nov 23, 2015 at 09:56am

  @RobertRobinson I'm the lead designer and project manager on the Honeywell systems.

  I can tell you exactly how I designed it. It's actually quite simple. Nothing is sent back to the unit. The unit is allowed access to the Internet via your setup and the router. As long as the unit has permission to make an outbound connection it will work. What happens is the unit makes a report to the server. If it needs to make a request then it gives the server a unique key. The server puts any needed data in an xml (readable) and the thermostat (or quite a few other devices) hits that URL a few seconds later (the device told the server where it would pick up that info).

  All your device needs is a simple read-only connection to the outside world. No need to download anything.
  It's a VERY simple process that I developed back in 1992 when the Interwebs were still pretty new to most people. There were many processes built off of this simple idea (it was pretty cutting edge when I first designed it). Store and forward, offline browsing, push technology, etc. all are based on this simple technology.

  Am I rich? Not even close. I was working on my PhD at the time and was hired by Honeywell to implement my design. I literally gave it away to the general public as is right.

  I hope that clears it up for you. If not, feel free to contact me for more information.

  Chris Dahlkvist
  chris@usarf.org

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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.

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:

1. 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.
2. 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.

1. 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.
2. 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.

Show Mac Address For Ip

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.

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.

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.

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.

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.

RARP was quickly replaced by DHCP and BOOTP.

But ARP is still one of the core functions of the IP layer in the TCP/IP protocol stack.

It finds MAC addresses from known IPs, which is most common in today’s communications.

ARP works under the hood to keep a frequently used list of MACs and IPs.

But you can also use it to see the current mappings with the command arp -a.

Aside from ARP, you can also use DHCP to view IP information. DHCP Servers are usually in charge of IP assignments.

If you have access to the DHCP server, go into the DHCP Client list and identify the IP with the MAC address.

Find Ip Address Mac Address Cisco Switch

Finally, you can use a network sniffer like Nmap, scan your entire network, and find IPs, and MACs.

Find Ip Address Using Mac Address

If you only want to know the vendor, an online OUI lookup like Wireshark can help you find it quickly.