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On Ubuntu 14.04 LTS

Using Google'd instructions, i.e. from:

  1. https://www.maketecheasier.com/change-mac-address-windows-ubuntu/
  2. How do I change / spoof my MAC address and easily switch between multiple ones?
  3. How to change the MAC address of pc?

I was able to change (spoof, clone, mask) my MAC address to connect to the internet successfully using these instructions, both using the method to change it through the terminal and through the Edit Connections UI. One reason one might wish to do this is for personal privacy.

However, currently when I use either method to clone my MAC Address, I can no longer connect to any WiFi networks successfully. I have been able to find no reason why this would be the case and completely lost as to discover the reason why this is happening with Ubuntu for me.

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Drawninpictures
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    Are you spoofing the MAC of your ethernet or your wireless? Because you say that "you are able to connect to the internet successfully". Do you see wireless networks? Do you get any error messages, or what happens? Cheers, Al – heynnema Oct 17 '16 at 15:14
  • I'm spoofing the wireless MAC. I am able to connect to the net but after spoofing cannot connect anymore. No error messages, and I do see all wireless networks. Not much happens really when I try to connect, it just attempts to connect for what appears the max duration timeout and then Ubuntu says "disconnected from network." I then erase the spoof mac address field, connect to the wireless network and can connect instantly and everything works fine. – Drawninpictures Oct 22 '16 at 13:28
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    Have you selected the original MAC address into the Device field using the popup? Try entering the original MAC address into the Cloned Mac Address field, and see if it connects then. Report back. Cheers, Al – heynnema Oct 22 '16 at 13:45
  • Hey thanks for getting back. So I copied the original MAC address into the Cloned address field and connected quickly without any problem. I then changed one character, a D to a C, and tried to reconnect but was not able to. Same thing happened, attempted to connect for a long duration and then gave the message "disconnected from network." – Drawninpictures Oct 22 '16 at 23:41
  • So we have a clue! There must be something about creating a valid MAC address. Lets go Google it! Keep me posted. Quick hit at http://sqa.fyicenter.com/Online_Test_Tools/MAC_Address_Format_Validator.php and http://serverfault.com/questions/40712/what-range-of-mac-addresses-can-i-safely-use-for-my-virtual-machines Cheers, Al – heynnema Oct 22 '16 at 23:44

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After determining that we could use the computer's original MAC address to spoof itself, and that changing just one character could break it, a Google search for "valid MAC address" turned up a wealth of information.

There are actually 4 sets of Locally Administered Address Ranges that can be used on your network without fear of conflict, assuming no one else has assigned these on your network:

x2-xx-xx-xx-xx-xx
x6-xx-xx-xx-xx-xx
xA-xx-xx-xx-xx-xx
xE-xx-xx-xx-xx-xx

Replacing x with any hex value.

Useful translation of the wikipedia version: "Universally administered and locally administered addresses are distinguished by setting the second least significant bit of the most significant byte of the address. If the bit is 0, the address is universally administered. If it is 1, the address is locally administered. In the example address 02-00-00-00-00-01 the most significant byte is 02h. The binary is 00000010 and the second least significant bit is 1. Therefore, it is a locally administered address.[3] The bit is 0 in all OUIs." – Adam Brand

In universally administered MAC addresses, the three most significant bytes are preassigned to specific companies/vendors.

A MAC address validator can be found at http://sqa.fyicenter.com/Online_Test_Tools/MAC_Address_Format_Validator.php.

heynnema
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    I don't see how that is at all helpful. The only reason to use one of these addresses is to make sure that it does not conflict with a "real" address on the network, but the odds of that happening are very low, and you already established it isn't the specific address he is trying to use, but any address other than the preprogrammed one. – psusi Oct 23 '16 at 01:08
  • @psusi That's not correct. We first solved the OPs original wireless connectivity problem by assigning a known working MAC address into the Clone field in his network configuration. Then we determined how to break it. And that clue lead us to determine that there was a specific format required. We determined that arbitrary MAC addresses that the OP was assigning may not work because they conflict with known preassigned addresses, and that there is a standard range of MAC addresses that could/should be used for local networks. – heynnema Oct 23 '16 at 01:18
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    You misunderstand... there is no specific address required... the addresses you reference are ones that are allocated for you to use so that you can be sure that if you pick one at random, it can not possibly conflict with other factory assigned addresses. A common use of cloning is to use the same MAC address as a previously existing system, provided that it is no longer also connected to the network. The OP already had previously had no trouble using whatever MAC address he wanted. Both of these show that it is not required that you use a locally administered address. – psusi Oct 23 '16 at 02:59
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    So then, why couldn't the OP make a wireless connection using the original MAC of his choice? And why, after using the original MAC address as his clone address, having it work, then changing a D to a C cause it to stop working? – heynnema Oct 23 '16 at 04:01
  • Some drivers refuse to use any address other than the one assigned by the factory. Also some access points have security restrictions to only allow certain MAC addresses. – psusi Oct 23 '16 at 20:22
  • Thank you heynnema for looking into it, but this solution does not work. I did previously go down that path of Googling for valid MAC addresses, but even while doing that knew that it would most likely not solve my problem because I was previously able to enter a random MAC address into the Cloned field and connect w/o issue. Thank you also psusi for the input. Unfortunately I am still without a solution and out of ideas for path of investigation to resolve this. If it was a driver issue, it must be a driver that Ubuntu updated since it previously worked. Also, I've tried this on 20+ networks – Drawninpictures Oct 25 '16 at 05:57
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    I'm sorry we couldn't get it resolved. So, are you saying, that 02-00-00-00-00-01 doesn't work either? Cheers, Al – heynnema Oct 25 '16 at 13:16
  • My comments here seem to have been removed or never posted? Yes it does not work... – Drawninpictures Jan 19 '17 at 08:46