Reliable method to get machine s MAC address in C

Question

I need a way to get a machine s MAC address  regardless of the OS it is running  by using C   The application will need to work on XP Vista Win7 32bit and 64bit  as well as on those OSs but with a foreign language default  Also  many of the C  commands and OS queries don t work across all the OSs  Do you have any ideas  I have been scraping the output of ipconfig  all but this is terribly unreliable as the output format differs on every machine

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string mac       foreach  NetworkInterface nic in NetworkInterface GetAllNetworkInterfaces                                   if  nic OperationalStatus    OperationalStatus Up  amp  amp    nic Description Contains  Virtual    amp  amp   nic Description Contains  Pseudo                                           if  nic GetPhysicalAddress   ToString                                                        mac   nic GetPhysicalAddress   ToString                                                          MessageBox Show mac

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ipconfig exe is implemented using various DLLs including iphlpapi dll     Googling for iphlpapi reveals a corresponding Win32 API documented in MSDN

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Changed blak3r his code a bit  In case you have two adapters with the same speed  Sort by MAC  so you always get the same value   public string GetMacAddress         const int MIN MAC ADDR LENGTH   12      string macAddress   string Empty      Dictionary lt string  long gt  macPlusSpeed   new Dictionary lt string  long gt         try               foreach NetworkInterface nic in NetworkInterface GetAllNetworkInterfaces                          System Diagnostics Debug WriteLine  Found MAC Address      nic GetPhysicalAddress       Type      nic NetworkInterfaceType                string tempMac   nic GetPhysicalAddress   ToString                 if  string IsNullOrEmpty tempMac   amp  amp  tempMac Length  gt   MIN MAC ADDR LENGTH                  macPlusSpeed Add tempMac  nic Speed                      macAddress   macPlusSpeed OrderByDescending row   gt  row Value  ThenBy row   gt  row Key  FirstOrDefault   Key            catch        System Diagnostics Debug WriteLine  Fastest MAC address      macAddress        return macAddress

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Try this             lt summary gt          returns the first MAC address from where is executed           lt  summary gt           lt param name  flagUpOnly  gt if sets returns only the nic on Up status lt  param gt           lt returns gt  lt  returns gt      public static string   getOperationalMacAddresses Boolean flagUpOnly                string   macAddresses   new string NetworkInterface GetAllNetworkInterfaces   Count              int i   0          foreach  NetworkInterface nic in NetworkInterface GetAllNetworkInterfaces                          if  nic OperationalStatus    OperationalStatus Up     flagUpOnly                                macAddresses i     ByteToHex nic GetPhysicalAddress   GetAddressBytes                       break                  i                                    return macAddresses

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Cleaner solution  var macAddr                  from nic in NetworkInterface GetAllNetworkInterfaces           where nic OperationalStatus    OperationalStatus Up         select nic GetPhysicalAddress   ToString         FirstOrDefault      Or   String firstMacAddress   NetworkInterface      GetAllNetworkInterfaces        Where  nic   gt  nic OperationalStatus    OperationalStatus Up  amp  amp  nic NetworkInterfaceType    NetworkInterfaceType Loopback        Select  nic   gt  nic GetPhysicalAddress   ToString          FirstOrDefault

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WMI is the best solution if the machine you are connecting to is a windows machine  but if you are looking at a linux  mac  or other type of network adapter  then you will need to use something else   Here are some options    Use the DOS command nbtstat -a    Create a process  call this command  parse the output  First Ping the IP to make sure your NIC caches the command in it s ARP table  then use the DOS command arp -a    Parse the output of the process like in option 1  Use a dreaded unmanaged call to sendarp in the iphlpapi dll   Heres a sample of item  3   This seems to be the best option if WMI isn t a viable solution   using System Runtime InteropServices       DllImport  iphlpapi dll   ExactSpelling   true           public static extern int SendARP int DestIP  int SrcIP  byte   pMacAddr  ref uint PhyAddrLen       private string GetMacUsingARP string IPAddr        IPAddress IP   IPAddress Parse IPAddr       byte   macAddr   new byte 6       uint macAddrLen    uint macAddr Length       if  SendARP  int IP Address  0  macAddr  ref macAddrLen     0          throw new Exception  ARP command failed         string   str   new string  int macAddrLen       for  int i   0  i  lt  macAddrLen  i            str i    macAddr i  ToString  x2         return string Join      str       To give credit where it is due  this is the basis for that code  http   www pinvoke net default aspx iphlpapi sendarp

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This method will determine the MAC address of the Network Interface used to connect to the specified url and port  All the answers here are not capable of achieving this goal  I wrote this answer years ago  in 2014    So I decided to give it a little  quot face lift quot    Please look at the updates section          lt summary gt          Get the MAC of the Netowrk Interface used to connect to the specified url           lt  summary gt           lt param name  quot allowedURL quot  gt URL to connect to  lt  param gt           lt param name  quot port quot  gt The port to use  Default is 80  lt  param gt           lt returns gt  lt  returns gt      private static PhysicalAddress GetCurrentMAC string allowedURL  int port   80                  create tcp client         var client   new TcpClient               start connection         client Client Connect new IPEndPoint Dns GetHostAddresses allowedURL  0   port               wai while connection is established         while  client Connected                        Thread Sleep 500                        get the ip address from the connected endpoint         var ipAddress     IPEndPoint client Client LocalEndPoint  Address             if the ip is ipv4 mapped to ipv6 then convert to ipv4         if ipAddress IsIPv4MappedToIPv6              ipAddress   ipAddress MapToIPv4                     Debug WriteLine ipAddress              disconnect the client and free the socket         client Client Disconnect false                      this will dispose the client and close the connection if needed         client Close             var allNetworkInterfaces   NetworkInterface GetAllNetworkInterfaces               return early if no network interfaces found         if   allNetworkInterfaces  Length  gt  0               return null           foreach var networkInterface in allNetworkInterfaces                          get the unicast address of the network interface             var unicastAddresses   networkInterface GetIPProperties   UnicastAddresses                            skip if no unicast address found             if   unicastAddresses  Count  gt  0                   continue                 compare the unicast addresses to see                if any match the ip address used to connect over the network             for var i   0  i  lt  unicastAddresses Count  i                                  var unicastAddress   unicastAddresses i                      this is unlikely but if it is null just skip                 if unicastAddress Address    null                      continue                                   var ipAddressToCompare   unicastAddress Address                   Debug WriteLine ipAddressToCompare                      if the ip is ipv4 mapped to ipv6 then convert to ipv4                 if ipAddressToCompare IsIPv4MappedToIPv6                      ipAddressToCompare   ipAddressToCompare MapToIPv4                     Debug WriteLine ipAddressToCompare                      skip if the ip does not match                 if  ipAddressToCompare Equals ipAddress                       continue                     return the mac address if the ip matches                 return networkInterface GetPhysicalAddress                                                      not found so return null         return null         To call it you need to pass a URL to connect to like this  var mac   GetCurrentMAC  quot www google com quot     You can also specify a port number   If not specified default is 80  UPDATES  2020  Added comments to explain the code  Corrected to be used with newer operating systems that use IPV4 mapped to IPV6   like windows 10    Reduced nesting  Upgraded the code use  quot var quot

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public static PhysicalAddress GetMacAddress         var myInterfaceAddress   NetworkInterface GetAllNetworkInterfaces            Where n   gt  n OperationalStatus    OperationalStatus Up  amp  amp  n NetworkInterfaceType    NetworkInterfaceType Loopback           OrderByDescending n   gt  n NetworkInterfaceType    NetworkInterfaceType Ethernet           Select n   gt  n GetPhysicalAddress             FirstOrDefault         return myInterfaceAddress

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Really hate to dig up this old post but I feel the question deserves another answer specific to windows 8-10    Using NetworkInformation from the Windows Networking Connectivity namespace  you can get the Id of the network adapter windows is using   Then you can get the interface MAC Address from the previously mentioned GetAllNetworkInterfaces     This will not work in Windows Store Apps as NetworkInterface in System Net NetworkInformation does not expose GetAllNetworkInterfaces   string GetMacAddress         var connectionProfile   NetworkInformation GetInternetConnectionProfile        if  connectionProfile    null  return          var inUseId   connectionProfile NetworkAdapter NetworkAdapterId ToString  B   ToUpperInvariant        if string IsNullOrWhiteSpace inUseId   return          var mac   NetworkInterface GetAllNetworkInterfaces            Where n   gt  inUseId    n Id           Select n   gt  n GetPhysicalAddress   GetAddressBytes   Select b  gt b ToString  X2              Select macBytes   gt  string Join      macBytes            FirstOrDefault         return mac

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foreach  NetworkInterface nic in NetworkInterface GetAllNetworkInterfaces           if  nic OperationalStatus    OperationalStatus Up                     PhysicalAddress Mac   nic GetPhysicalAddress

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You could go for the NIC ID    foreach  NetworkInterface nic in NetworkInterface GetAllNetworkInterfaces           if  nic OperationalStatus    OperationalStatus Up            if  nic Id     yay                It s not the MAC address  but it is a unique identifier  if that s what you re looking for

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We use WMI to get the mac address of the interface with the lowest metric  e g  the interface windows will prefer to use  like this   public static string GetMACAddress         ManagementObjectSearcher searcher   new ManagementObjectSearcher  SELECT   FROM Win32 NetworkAdapterConfiguration where IPEnabled true        IEnumerable lt ManagementObject gt  objects   searcher Get   Cast lt ManagementObject gt         string mac    from o in objects orderby o  IPConnectionMetric   select o  MACAddress   ToString    FirstOrDefault        return mac      Or in Silverlight  needs elevated trust    public static string GetMACAddress         string mac   null      if   Application Current IsRunningOutOfBrowser   amp  amp   Application Current HasElevatedPermissions   amp  amp   AutomationFactory IsAvailable                 dynamic sWbemLocator   AutomationFactory CreateObject  WbemScripting SWBemLocator            dynamic sWbemServices   sWbemLocator ConnectServer               sWbemServices Security  ImpersonationLevel   3    impersonate          string query    SELECT   FROM Win32 NetworkAdapterConfiguration where IPEnabled true           dynamic results   sWbemServices ExecQuery query            int mtu   int MaxValue          foreach  dynamic result in results                        if  result IPConnectionMetric  lt  mtu                                mtu   result IPConnectionMetric                  mac   result MACAddress                                    return mac

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The MACAddress property of the Win32 NetworkAdapterConfiguration WMI class can provide you with an adapter s MAC address   System Management Namespace   MACAddress      Data type  string     Access type  Read-only      Media Access Control  MAC  address of the network adapter  A MAC address is assigned by the manufacturer to uniquely identify the network adapter       Example   00 80 C7 8F 6C 96    If you re not familiar with the WMI API  Windows Management Instrumentation   there s a good overview here for  NET apps   WMI is available across all version of windows with the  Net runtime   Here s a code example   System Management ManagementClass mc   default System Management ManagementClass   ManagementObject mo   default ManagementObject   mc   new ManagementClass  Win32 NetworkAdapterConfiguration     ManagementObjectCollection moc   mc GetInstances        foreach  var mo in moc            if  mo Item  IPEnabled      true                  Adapter Items Add  MAC     mo Item  MacAddress   ToString

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Here s some C  code which returns the MAC address of the first operational network interface  Assuming the NetworkInterface assembly is implemented in the runtime  i e  Mono  used on other operating systems then this would work on other operating systems   New version  returns the NIC with the fastest speed that also has a valid MAC address        lt summary gt      Finds the MAC address of the NIC with maximum speed       lt  summary gt       lt returns gt The MAC address  lt  returns gt  private string GetMacAddress         const int MIN MAC ADDR LENGTH   12      string macAddress   string Empty      long maxSpeed   -1       foreach  NetworkInterface nic in NetworkInterface GetAllNetworkInterfaces                  log Debug               Found MAC Address      nic GetPhysicalAddress                   Type      nic NetworkInterfaceType            string tempMac   nic GetPhysicalAddress   ToString            if  nic Speed  gt  maxSpeed  amp  amp               string IsNullOrEmpty tempMac   amp  amp              tempMac Length  gt   MIN MAC ADDR LENGTH                        log Debug  New Max Speed       nic Speed      MAC      tempMac               maxSpeed   nic Speed              macAddress   tempMac                       return macAddress      Original Version  just returns the first one        lt summary gt      Finds the MAC address of the first operation NIC found       lt  summary gt       lt returns gt The MAC address  lt  returns gt  private string GetMacAddress         string macAddresses   string Empty       foreach  NetworkInterface nic in NetworkInterface GetAllNetworkInterfaces                  if  nic OperationalStatus    OperationalStatus Up                        macAddresses    nic GetPhysicalAddress   ToString                break                       return macAddresses      The only thing I don t like about this approach is if you have like a Nortel Packet Miniport or some type of VPN connection it has the potential of being chosen  As far as I can tell  there is no way to distinguish an actual physical device s MAC from some type of virtual network interface

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I really like AVee s solution with the lowest IP connection metric  But if a second nic with the same metric is installed  the MAC comparison could fail     Better you store the description of the interface with the MAC  In later comparisons you can identify the right nic by this string  Here is a sample code      public static string GetMacAndDescription                 ManagementObjectSearcher searcher   new ManagementObjectSearcher  SELECT   FROM Win32 NetworkAdapterConfiguration where IPEnabled true            IEnumerable lt ManagementObject gt  objects   searcher Get   Cast lt ManagementObject gt             string mac    from o in objects orderby o  IPConnectionMetric   select o  MACAddress   ToString    FirstOrDefault            string description    from o in objects orderby o  IPConnectionMetric   select o  Description   ToString    FirstOrDefault            return mac         description             public static string GetMacByDescription  string description                ManagementObjectSearcher searcher   new ManagementObjectSearcher  SELECT   FROM Win32 NetworkAdapterConfiguration where IPEnabled true            IEnumerable lt ManagementObject gt  objects   searcher Get   Cast lt ManagementObject gt             string mac    from o in objects where o  Description   ToString      description select o  MACAddress   ToString    FirstOrDefault            return mac

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let s say I have a TcpConnection using my local ip of 192 168 0 182  Then if I will like to know the mac address of that NIC I will call the meothod as  GetMacAddressUsedByIp  192 168 0 182    public static string GetMacAddressUsedByIp string ipAddress                var ips   new List lt string gt             string output           try                          Start the child process              Process p   new Process                   Redirect the output stream of the child process              p StartInfo UseShellExecute   false               p StartInfo RedirectStandardOutput   true              p StartInfo UseShellExecute   false              p StartInfo CreateNoWindow   true              p StartInfo FileName    ipconfig               p StartInfo Arguments     all               p Start                   Do not wait for the child process to exit before                reading to the end of its redirected stream                 p WaitForExit                   Read the output stream first and then wait              output   p StandardOutput ReadToEnd                p WaitForExit                       catch                       return null                        pattern to get all connections         var pattern       xis      lt Header gt         r  n     r       r n r n      lt content gt                  r n r n                      List lt Match gt  matches   new List lt Match gt              foreach  Match m in Regex Matches output  pattern               matches Add m            var connection   matches Select m   gt  new                       containsIp   m Value Contains ipAddress               containsPhysicalAddress   Regex Match m Value      ix Physical  s Address   Success              content   m Value            Where x   gt  x containsIp  amp  amp  x containsPhysicalAddress           Select m   gt  Regex Match m content      ix   Physical  s address          s     lt Mac gt    s      Groups  Mac   Value  FirstOrDefault             return connection

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IMHO returning first mac address isn t good idea  especially when virtual machines are hosted  Therefore i check send received bytes sum and select most used connection  that is not perfect  but should be correct 9 10 times   public string GetDefaultMacAddress         Dictionary lt string  long gt  macAddresses   new Dictionary lt string  long gt         foreach  NetworkInterface nic in NetworkInterface GetAllNetworkInterfaces                  if  nic OperationalStatus    OperationalStatus Up              macAddresses nic GetPhysicalAddress   ToString      nic GetIPStatistics   BytesSent   nic GetIPStatistics   BytesReceived            long maxValue   0      string mac           foreach KeyValuePair lt string  long gt  pair in macAddresses                if  pair Value  gt  maxValue                        mac   pair Key              maxValue   pair Value                      return mac

[c#] Reliable method to get machine's MAC address in C#

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