I have been asked many times this question, in person as well as over email. Many people are clueless that you can even change MAC address and give open challenges, so forget that they would know why there is a need to change a MAC address.
Some people think that websites on Internet can track users using MAC address and so they must change it! Well, your MAC address wont go further than the first router the IP packet gets to.
If you want to change your MAC address and have a specific one in mind, you can set it with: sudo ifconfig en0 ether aa:bb:cc:dd:ee:ff. This will set your MAC address for en0. If you have a Mac that also has an ethernet port, you may need to use en1. How to Get a Random MAC Address. If you’re going for privacy, randomizing your MAC address is probably the best option.
Its because, MAC address is used as unique identifier at data link layer (OSI layer 2), like for example your local Ethernet, while the IP packet being forwarded over Internet is at network level (OSI layer 3) and uses IP Address as a global unique identifier (which websites can see and track). And when an Ethernet frame reaches a router, the router's MAC address is used to send the frame forward. So, clearly this is not a reason to change MAC address! There are many reasons you would want change MAC address, some legitimate others not so. I am listing some of the legitimate reasons while you wonder what the other reasons might be! • Your ISP uses MAC address to identify or authenticate your Internet connection. So in case your network card goes boom, the new card you replace it with will have different MAC address and so the Internet wont work.
So changing the MAC address to old network adapter is the quickest fix instead of telling your ISP to register your new MAC address which may take lot of time. • If you want to access a network, which limits access based on MAC address, from another machine then you can change MAC address to the one for which you have access. Note that only one computer would be able to access the same network (no two computers can have same MAC address on same network to access it without any problem) • A very important reason is privacy. Your MAC address can be seen by everyone on the local Ethernet network using many simple tools. A hacker on local network thus can track machines (and thus you) on the network.
This is especially a threat when you are on a wireless network and are using a public WiFi network like in coffee shops, hotels or airports. • If your original MAC address is revealed, an hacker can use it to impersonate you! On many networks (wired or wireless) access is restricted based on MAC address to avoid access to unauthorized devices on the network. So, when you go offline, someone can use your machine's MAC address and access the network as 'you'.
• You can get a new IP address lease from DHCP server by changing MAC address. On many networks, DHCP lease is set to last many days or is associated directly with a MAC address such that you get the same IP address all the time. The reasons I listed above are just the ones that came to my mind while writing this post.
There are many more reasons (sometime bizarre) to change MAC address. If you change MAC address for some reason not on the list above, do post it as a comment below. A website cannot know what your MAC address is. It can know your public IP address which normally is dynamic and you will get a new IP every time you connect to internet. The way sites track users is using browser cookies, flash cookies & ETags. So you can just set your browser to clear cookies when it closes. I would recommend you to use Firefox browser with BetterPrivacy addon which can clear flash cookies when browser closes.
Also, make sure you clear your browser cache so that all the ETags are flushed. Best is to create different profiles in Firefox using Profile Manager (start firefox with -p option, google for more details). Every profile created has its own cache, history, cookies etc. So its best to have when you need complete separation. Changed MAC address will stay until you revert to original MAC address.
The changes are made only in software and wont affect any other thing. There is no issue with OS registration, however some software do use MAC address to identify the computer and thus may not work. There are very few software that do use it though. Some internet service providers (ISP) too use it as additional parameter to verify customers. In such case, the internet connection wont work after changing MAC address. You may use this tool in such case to use Internet on another computer by changing its MAC address to the one registered with the ISP. Anonymous Hi,I Have a problem with a small library network(because i forgot the torrent open.and they don't believe me that my purpose wasn't to download The Big Bang Theory but studied)!
Mimecast for mac. Download Mimecast for Mac. For standalone installations, you can download the disk image (DMG file) and have users initiate the installation of Mimecast for Mac.