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MAC Address Scan

Remote Shutdown needs to know the remote Machines' MAC addresses to be able to provide you with the Wake-on-LAN feature. Media Access Control (MAC) address is a unique identifier assigned to most network adapters and network interface cards (NICs) by the manufacturer for identification and used in the Media Access Control protocol sub-layer.

MAC Address Scan is executed automatically during the Network Scan process or when Machines are being added manually. It is also possible to execute MAC Address Scan for selected Machines manually using the Retrieve MAC Address button from the Network Ribbon Group.

Methods of retrieving MAC address

Remote Shutdown supports four methods of retrieving MAC addresses from remote Machines. The methods to be used should be specified on the MAC Address Scan preference page. Each method has its pros and cons and is described in detail below.

Neighbor Discovery

ARP (Address Resolution Protocol) is used to identify the MAC address associated with a certain IP address. If a machine has a packet bound for another IP on a locally connected Ethernet network, it  sends a broadcast Ethernet frame containing an ARP request to the Ethernet. That packet will be received by all machines with the same Ethernet broadcast address. If a machine receiving the ARP request hosts the requested IP, it will respond with the link layer address, at which it will receive packets for that IP address. Once the requester receives the response packet, it will start associating the MAC address with the respective IP address. That information is stored in the ARP cache, which is available on individual network adapters as well as on IP routers.

Info

The Neighbor Discovery method can retrieve MAC addresses only for the Machines located in the same subnet as the Remote Shutdown hosting Machine.

NetBIOS

NetBIOS (Network Basic Input/Output System) provides services related to the session layer of the OSI model allowing applications on separate computers to communicate over a local area network.

WinAPI

Windows API is Microsoft's core set of application programming interfaces (APIs) available in the Microsoft Windows operating systems.

WMI

Windows Management Instrumentation (WMI) is a set of extensions to the Windows Driver Model that form an operating system interface through which instrumented components provide information and notification. WMI is used to access and manage data on remote computers. Remote connections in WMI are affected by Windows Firewall and Distributed Component Object Model (DCOM) settings. Windows Firewall is enabled by default and set to block any data requests from remote Machines and callbacks resulting from asynchronous calls. The firewall and DCOM settings must be configured to allow such connections. For Windows Vista and later OS, it is also required to configure User Account Control (UAC).

Warning

Changing DCOM settings may allow remote access to the Machine for low-rights users. Refer to the Setting DCOM Security to Allow a User to Access a Computer Remotely document for the instructions on DCOM security configuration.

Methods comparison

Method

Advantages

Disadvantages

Neighbor Discovery

High processing speed. Administrative privileges on remote Machines are not required.

Ability to process Machines only within a local subnet.

NetBIOS

High processing speed. Administrative privileges on remote Machines are not required.

Ability to process Machines only within a single physical network. Requires that the NetBIOS protocol should be enabled.

WinAPI

Ability to process any kind of Machine regardless of its location.

Lower processing speed compared to other methods. Requires administrative privileges on remote Machines.

WMI

Ability to process any kind of Machine regardless of its location.

Requires administrative privileges on remote Machines. Turned off by default on most Machines.