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Maintaining and Changing the MAC Address of a Virtual Machine
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When a virtual machine is powered on, VMware Workstation automatically assigns each of its virtual network adapters an Ethernet MAC address. MAC stands for media access control. A MAC address is the unique address assigned to each Ethernet network device.
The software guarantees that virtual machines are assigned unique MAC addresses within a given host system. In most cases, the virtual machine is assigned the same MAC address every time it is powered on, so long as the virtual machine is not moved (the path and filename for the virtual machine's configuration file must remain the same) and no changes are made to certain settings in the configuration file.
In addition, VMware Workstation does its best, but cannot guarantee, to automatically assign unique MAC addresses for virtual machines running on multiple host systems.
Avoiding MAC Changes
To avoid changes in the MAC address automatically assigned to a virtual machine, you must not move the virtual machine's configuration file. Moving it to a different host computer or even moving it to a different location on the same host computer changes the MAC address.
You also need to be sure not to change certain settings in the virtual machine's configuration files. If you never edit the configuration file by hand and do not remove the virtual Ethernet adapter, these settings remain untouched. If you do edit the configuration file by hand, be sure not to remove or change the following options:
ethernet[n].generatedAddress
ethernet[n].addressType
ethernet[n].generatedAddressOffset
uuid.location
uuid.bios
ethernet[n].present
In these options, [n] is the number of the virtual Ethernet adapter, for example ethernet0.
Note: To preserve a virtual Ethernet adapter's MAC address, you also must be careful not to remove the adapter. If you remove the adapter, then recreate it, the adapter may receive a different MAC address.
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Manually Assigning a MAC Address
If you want to guarantee that the same MAC address is assigned to a given virtual machine every time, even if the virtual machine is moved, or if you want to guarantee a unique MAC address for each virtual machine within a networked environment, you can assign the address manually instead of allowing VMware Workstation to assign it automatically.
To assign the same, unique MAC address to any virtual machine manually, use a text editor to remove three lines from the configuration file and add one line. The configuration file has a.vmx extension at the end of the filename. On a Linux host, a virtual machine created with an earlier VMware product may have a configuration file with a .cfg extension.
Remove the three lines that begin with the following from the configuration file:
ethernet[n].generatedAddress
ethernet[n].addressType
ethernet[n].generatedAddressOffset
In these options, [n] is the number of the virtual Ethernet adapter — for example ethernet0.
Add the following line to the configuration file:
ethernet[n].address = 00:50:56:XX:YY:ZZ
In this line, XX must be a valid hexadecimal number between 00h and 3Fh, and YY and ZZ must be valid hexadecimal numbers between 00h and FFh. Because VMware Workstation virtual machines do not support arbitrary MAC addresses, you must use the above format.
So long as you choose a value for XX:YY:ZZ that is unique among your hard-coded addresses (where XX is a valid hexadecimal number between 00h and 3Fh, and YY and ZZ are valid hexadecimal numbers between 00h and FFh), conflicts between the automatically assigned MAC addresses and the manually assigned addresses should never occur.
The ability to switch between different sets of network settings (locations) can be useful in circumstances such as these:
- You use the same type of network (such as Ethernet) at work and at home, but the settings you use at work don't allow your Mac to automatically connect to the same type of network at home.
- Your Mac connects to more than one type of network service (such as both Wi-Fi and Ethernet) at work and at home, but at work you want your Mac to try connecting to the Ethernet network first, and at home you want your Mac to try connecting to the Wi-Fi network first. In other words, you want to set a different service order for each location.
- Your Mac isn't connecting to your network and you want to quickly reset your network settings for testing purposes, without losing your current network settings.
In each of these examples, the Location feature of Network preferences can help.
How to add or remove a network location
- Choose Apple menu () > System Preferences, then click Network.
- The Location pop-up menu shows the name of your currently selected set of network settings. The default location is named Automatic. Choose Edit Locations from this menu.
- Click the Add (+) button below the list of locations, then type a name for the new location, such as Work or Home or Mobile. (To remove a location, use the Remove (–) button below the list.)
- Click Done. The Location menu should now show the name of your new location. Any changes you now make to your Wi-Fi, Ethernet, or other network settings will be saved to that location when you click Apply. The network settings in your previous location remain as you left them, so you can use the Location menu to switch back at any time.
- Click Apply to save your settings and complete the switch from the previous location to the new one. Your Mac then automatically tries to determine the correct settings for each type of network. If you need to change the settings manually, remember to click Apply again after making your changes.
How to switch between network locations
If you have more than one location, you can use either of these methods to switch between them:
- Use the Location pop-up menu in Network preferences, as described above. Remember to click Apply after choosing a location.
- Or choose Apple menu > Location from the menu bar, then choose your location from the submenu.
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How to change the network service order
If you're using network locations because you want each location to prefer a different network service (such as Wi-Fi or Ethernet) when connecting, follow these steps to change the service order (also known as port priority) in each location.
- Choose Apple menu > System Preferences, then click Network.
- Use the Location menu to choose the location you want to modify.
- Click below the list of services, then choose Set Service Order.
- Drag services within the list to change their order. Your Mac will try to connect to the service at the top of the list first, then continue in descending order until a connection is successful.
Virtual private network (VPN) connections can't be reordered, because they always take priority over other connections. - Click OK, then click Apply to make the updated service order active.
How to prevent a network service from being used
By default, the location named Automatic makes all available network services (also known as ports or network interfaces) active, whether or not they are being used to connect to a network. Your Mac automatically searches these services for a network or Internet connection. For example, you might use a Wi-Fi network at home but an Ethernet network at work. Your Mac automatically detects which of these network services to use when it connects.
If you want to make sure that your Mac doesn't use a particular network service, such as Wi-Fi, you can make that service inactive in any of your network locations:
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- Choose Apple menu > System Preferences, then click Network.
- Use the Location menu to choose the location you want to modify.
- Click below of the list of services, then choose Make Service Inactive.
- Click Apply.