21-04-2021

Get Ip For Mac

Ping A Mac Address To Get Ip

An IP address is like an identity on the Internet. All computing devices connected to the Internet have an IP address. Sometimes, that address is static -- that means the address remains the same and the device will always have that address when connected to the Internet. Other addresses are dynamic, which means the device could potentially have a different IP address each time it connects to the Internet. Once connected, the IP address will remain constant but if the device disconnects and reconnects it may have another address.

As you can see, the 'sh arp' or 'sh ip arp' commands also give you the MAC addresses, so essentially the 'sh mac add' is only to get the port in which the device is connected. It helps to Ping the subnet's. CC Get MAC Address is a handy tool for finding MAC address and computer name from IP address. You can use it to find MAC address, computer name and IP address of a computer on LAN even out of your LAN range. Network administrator can use this handy tool to lookup mac address of each computer on the LAN. Can find out who change his IP or mac address for spoofing.

Why would you change your IP address? Sometimes your computer's IP address may have a conflict, either due to another device having the same address or your address format doesn't let you access the Internet. But there are a few reasons people want to change their computers' IP addresses that are on shaky ground from an ethical standpoint. Some services will block devices that have IP addresses from certain regions. The service might be a game, music service, video service or general Web site. If the system detects that you are from a region outside of its area of service, you won't be able to access it. Changing your IP address to one that appears to be from another region can grant you access.

Another reason people choose to change IP addresses has to do with getting blocked or banned from a service. A relatively easy way to ban a user is to block that user's IP address. But if you change your IP address it's like you're wearing a disguise.

Perhaps you want to protect your privacy while browsing sites and services. Changing your IP address and using a Web proxy can help protect your identity, which can come in handy if you're worried that someone might be snooping on you. People who live in regions that have oppressive or restrictive governments may use Web proxies to access information and communication systems that they otherwise wouldn't be able to reach.

If all you need is a new IP address because you're having network issues, follow these steps:

Close out of any applications that are connected to the Web.
Click on the Apple menu and choose System Preferences.
Go to the View menu and choose Network.
Go to the Show menu and choose Active Network Ports.
Click to deselect the checkbox for the port you use to connect to the Internet.
Click Apply Now, reselect the port checkbox and click Apply Now again.
Open a Web browser and try to connect to a Web page.
If this doesn't work, power cycling your modem (turning it off, waiting a few seconds and turning it back on) may help.

Keep in mind that this method will only reset your Mac's IP address to a new one within the same region. This method won't let you skirt laws and policies to let you view content that is off limits to you normally. To do that, you would need to use a Web proxy service. Such services may not be entirely reliable since many governments and companies frown upon them.

To learn more about operating systems and related topics, take a look at the links below.

Sources

Pure Darwin (Aug. 9, 2011) http://www.puredarwin.org/developers/xnu
Singh, Armit. 'What is Mac OS X?' OS X Books. December 2003. (Aug. 4, 2011) http://osxbook.com/book/bonus/ancient/whatismacosx/arch_xnu.html
Kibsgaard, Bjornar. 'History of Mac OS X.' 2011. (Aug. 4, 2011) http://www.all-about-apple.com/history-of-mac-os.html
CERN. 'Tim Berners-Lee's original World Wide Web browser.' 2008. (Aug. 4, 2011) http://info.cern.ch/NextBrowser.html
Computer Hope. 'Apple OS History.' (Aug. 5, 2011) http://www.computerhope.com/history/macos.htm
Apple. 'Mac 101.' 2011. (Aug. 4, 2011) http://www.apple.com/support/mac101/work/
Apple. 'OS X Lion.' 2011. (Aug. 4, 2011) http://www.apple.com/macosx/
Apple. 'Mac OS: How to release and renew a DHCP lease.' Feb. 15, 2011. (Aug. 11, 2011) http://support.apple.com/kb/TS1920

Learning has never been so easy!

As a Network Administrator/Engineer you may be asked to find MAC addresses and/or IP Addresses, hopefully this can make your job a little bit easier. These commands work on most Cisco Switches and Routers but sometimes the commands can vary from device to device.

5 Steps total

Step 1: Connect to your Cisco Devices

Connect to the Switch/Router by using a console cable or a terminal emulator like Putty or Secure CRT. If you are successful it should look something like this.

Step 2: Find The MAC Addresses

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 look like the picture. It's worth noting that on some Cisco devices the command 'show mac-address-table' also works.

Step 3: Find the IP Address

On the layer 3 device ( L3 switch or router) in my case I am using a router, enter the username and password if needed. Next enter 'enable' mode on the router by typing enable. Next type 'show ip arp' if done correctly you should get an output similar to the picture.

Step 4: Filtering the results on a Router

In the example I have provided there were only 9 IP addresses. However in the real world there could be dozens or even hundreds of IP addresses. To help filter the results on a router type 'show ip arp ?' You will see gigabitethernet' as an option this will let you filter results by interface or sub-interfaces. In my exmaple it typed 'sho ip arp gigabitEthernet 0/0.10' and that listed all IP's on my sub-interface.

Step 5: Filtering the results on a Layer 3 Switch

As stated in Step 4, you will likely have more than 9 IP Addresses. This can be made worse in a messy closet with a 48 port switch running the closet and maybe even some layer 2 switches under that. Luckily in addition to being able to filter by interface you can also filter by VLAN. So type in 'show ip arp ?' and you will see 'vlan' as a listed filter. As you can see I typed in 'sho ip arp vlan 20' and it listed only those IP's in vlan 20. In this case it was the vlan interface and a PC.

I hope this guide was helpful for you. If you aren't sure about something or feel like I missed a step, please let me know.

9 Comments

Ping A Mac Address To Get Ip

Anaheim
GDBJNC Apr 27, 2018 at 01:15pm
Great post.
Another way to find that information is to first PING the address of the system you are looking for. Then issue:
show arp | i .
This will then show you the MAC address associated with the IP address.
Then issue:
show mac address-table | i
This will give you the port that the device is currently connected.
Cayenne
Jim6795 Apr 27, 2018 at 01:15pm
Thanks for posting this *after* I finished a 'What's Connected Where' jihad on our network. :^D After beating Google to death over it, hoping for some useful tool, I ended up using exactly the same process (plus the online MAC address lookup to ID the device manufacturer), so I can affirm this works perfectly, if you work it.
As you can see, the 'sh arp' or 'sh ip arp' commands also give you the MAC addresses, so essentially the 'sh mac add' is only to get the port in which the device is connected. It helps to Ping the subnet's broadcast address (e.g. '10.1.1.255') to load the ARP table. (Small tip: When you see a large number of MAC addresses showing up on a single port, there's a switch on that port into which those MAC addresses are connected. If you're all Cisco, 'show cdp neighbor' (or 'sh cdp nei') will get you to the next switch. Also, 'sh ip arp | i 0/24' will show just the MAC address(es) on that port.)
The amazing thing to me is, this far into the 21st Century, this is still the only way I could find to get this information -- i.e. to find out what's connected where. Did I mention it's a *lot* of work?
(ETA: What if you can't get to the Console port? How do you get the IP address of the switch in order to SSH or (if you must) Telnet in?)
Datil
CrimsonKidA Apr 27, 2018 at 02:04pm
Good stuff, thanks for posting this! My go-to Cisco command is: show ip interface brief (show ip int bri). Another thing I've learned that is very helpful (I'm still a noob with Cisco stuff) is tab-completion and using a '?' after the start of a command, such as 'show ?'
Cayenne
Ed Rubin Apr 27, 2018 at 03:09pm
Unfortunately dumping the mac table and working through it is the only way to reliably find stuff and identify its switch port. I've done a similar process with HP switches. One thing that helps a lot is an ip scanner application that does MAC vendor ID lookups for you. This can help with jim6795's problem of identifying an undocumented switch IP since you can look for the the switch maker's vendor ID and then try ssh or telnet, or http/https depending on the product.
Jalapeno
TS79 Apr 27, 2018 at 06:53pm
Spiceworks has the ability to harvest this information using SNMP and will create a map showing which device is on which switchport. It must have the correct MIB installed for your switch and you must configure SNMP. The feature could use some more work but basic components are there.
Jalapeno
SadTech0 Apr 27, 2018 at 08:06pm
Thanks for posting this *after* I finished a 'What's Connected Where' jihad on our network. :^D After beating Google to death over it, hoping for some useful tool, I ended up using exactly the same process (plus the online MAC address lookup to ID the device manufacturer), so I can affirm this works perfectly, if you work it.
As you can see, the 'sh arp' or 'sh ip arp' commands also give you the MAC addresses, so essentially the 'sh mac add' is only to get the port in which the device is connected. It helps to Ping the subnet's broadcast address (e.g. '10.1.1.255') to load the ARP table. (Small tip: When you see a large number of MAC addresses showing up on a single port, there's a switch on that port into which those MAC addresses are connected. If you're all Cisco, 'show cdp neighbor' (or 'sh cdp nei') will get you to the next switch. Also, 'sh ip arp | i 0/24' will show just the MAC address(es) on that port.)
The amazing thing to me is, this far into the 21st Century, this is still the only way I could find to get this information -- i.e. to find out what's connected where. Did I mention it's a *lot* of work?
(ETA: What if you can't get to the Console port? How do you get the IP address of the switch in order to SSH or (if you must) Telnet in?)
Couldn't you just use CDP? #show cdp nei detail will show you the ip of the connected devices.
Thai Pepper
TaylorC Apr 27, 2018 at 08:45pm
Hey everyone thanks for the great feed back, it's really cool having this featured. @SadTech0 if you cant to the console port and you don't know the IP Address you could use a tool like angry IP scanner and find the switch that way. CDP may or may not work depending on your network configuration and/or topology. Barring some major obstruction you should try to console in get the ip and start an inventory. Hope that helps.
Thai Pepper
Todd_in_Nashville Apr 30, 2018 at 12:34pm
Keep in mind, in some security minded environments, CDP may be disable if it's not needed. It's one of those things that give out unnecessary reconnaissance info to the bad guys. If one of your edge routers gets compromised, it can be used to start footprinting your internal network.
Thai Pepper
John3367 Apr 30, 2018 at 08:51pm
Great info..
Another helpful thing you should add!
SHOW INVENTORY ---> To show the SERIAL number of the Cisco device you are on.
**I always use those commands you show to troublshoot. They are very helpful. I usually PING an IP address. then I type a 'show arp' and get its MAC address.. then I will type 'show mac-address table' which will show me which PORT the device is connected to!

Cowfox942