MacOS – Change mac id of usb-c to lan adapter

ethernetmacbook promacosthunderboltwindows

I recently got a Macbook pro 13 inch and I bought this docking station for all the ports I need. The issue is that my university network requires registration of mac id to use internet in campus and it's a cumbersome process. I already have a windows laptop that is registered so I wanted to change the mac id to start using my macbook. I followed this article to change my mac id, but I noticed two interfaces en1 and bridge0 have the same mac id, and I can only change mac id for bridge0 interface. Although changing mac id of bridge0 interface changes the mac id displayed in the advanced properties of Thunderbolt Bridge service in Network Preferences I still can't access internet. I am quite new to Mac OS and changing these stuff were quite simple in Windows, is there any way I can achieve what I want??

Update 1

I had a portable Windows installation lying around and I used it to boot into Windows on my macbook and I can change mac id and access internet perfectly on Windows, so it can't be related to any faulty hardware.

Update 2

After again booting into mac os now the interface in properly recognized in Network Preference as USB 10/100/1000 LAN and new interface name en7. I guess I only had to reboot after intallation of drivers but mac os didn't prompt me to do so. I followed the same article I linked before and trying to change mac id results in an error with message:

ifconfig: ioctl (SIOCAIFADDR): Operation not supported on socket

Also, using spoofmac as suggested results in same error as spoof-mac uses the same method to change mac id.

Best Answer

macOS has always been "iffy" when it came to spoofing MAC addresses unlike other OSes so it's not a (faulty) hardware issue. It's more of a "how Apple likes to do things" issue.

My advice is the following (in order):

Get that MAC address registered with the university.
Use SpoofMAC to, well, spoof your MAC address.

Yes, I think you should just bite the bullet and register your MAC with the university. Yes, it's a PITA, but the downside is simply too costly for the time you're attempting to save. If they happen to catch you (and they can), you're going to face disciplinary action because in the end, you agreed to their terms of service whether you remember agreeing to them or not.

That said, there are genuine uses for spoofing your MAC address and to do so on a Mac, you can use SpoofMAC. It's available via GitHub (see link above) or via Homebrew.

Once you have it installed, you simiply execute the following command with the actual MAC address and your network device as needed:

% spoof-mac.py set 00:00:00:00:00:00 en0

They also conveniently provide instructions for launching this at startup.

Related Solutions

MacOS – How to add external Interface to the OS X with a valid IP

In System Preferences -> Network click on the + to add a new interface, in the popup choose Ethernet. This will not create an additional en1 or en2 interface, but add an additional address to your en0 interface.

MacOS – Changing the range of addresses served to clients connected via Internet Sharing

This is specifically for Ethernet > Ethernet Sharing connections, rather than WiFi (it might work for WiFi but I haven't tested) - I thought the answer would best belong here, for Google.

Tested as working up to El Capitan 10.11.5

Apparently since Yosemite, adding just the SharingNetworkNumberStart key is no longer sufficient.
Also, System Prefs caches the NAT file located at /Library/Preferences/SystemConfiguration/com.apple.nat & will just overwrite your settings again, if you do things in the wrong order.
Actual addresses are, of course, your choice.

Switch off internet Sharing.
Close System Prefs

In Terminal type these 3 commands

sudo defaults write /Library/Preferences/SystemConfiguration/com.apple.nat NAT -dict-add SharingNetworkNumberStart 192.168.0.0
sudo defaults write /Library/Preferences/SystemConfiguration/com.apple.nat NAT -dict-add SharingNetworkNumberEnd 192.168.0.20
sudo defaults write /Library/Preferences/SystemConfiguration/com.apple.nat NAT -dict-add SharingNetworkMask 255.255.255.0

Open System Prefs > Network
Select what is to be your shared port & set as follows

Configure IPv4: Manually
IP Address: 192.168.0.1
Subnet Mask: 255.255.255.0
Router: 192.168.0.1
Then in Advanced... > DNS add the same Router Address as DNS server, in this case 192.168.0.1

OK, Apply.
Switch on Internet Sharing

Test your Bridge address in Terminal with ifconfig -a & check the line inet 192.168.0.1 netmask 0xffffff00 broadcast 192.168.0.255 is what you expected.

Info worked from Mac OS Hints: Change the default subnet for Internet Sharing