Get LAN Interface

uses WinInet

const
  MAX_PACKET_SIZE = $10000;
  SIO_RCVALL = $98000001;
  WSA_VER = $202;
  MAX_ADAPTER_NAME_LENGTH        = 256;
  MAX_ADAPTER_DESCRIPTION_LENGTH = 128;
  MAX_ADAPTER_ADDRESS_LENGTH     = 8;
  IPHelper = 'iphlpapi.dll';
  ICMP_ECHO             = 8;
  ICMP_ECHOREPLY        = 0;
  // LAN
  MODEM = 1;
  LAN = 2;
  PROXY = 4;
  BUSY = 8;

type
  USHORT = WORD;
  ULONG = DWORD;
  time_t = Longint;

  TIPHeader = packed record
    iph_verlen:   UCHAR;
    iph_tos:      UCHAR;
    iph_length:   USHORT;
    iph_id:       USHORT;
    iph_offset:   USHORT;
    iph_ttl:      UCHAR;
    iph_protocol: UCHAR;
    iph_xsum:     USHORT;
    iph_src:      ULONG;
    iph_dest:     ULONG;
  end;
  PIPHeader = ^TIPHeader;


  TTCPHeader = packed record
    sourcePort: USHORT;
    destinationPort: USHORT;
    sequenceNumber: ULONG;
    acknowledgeNumber: ULONG;
    dataoffset: UCHAR;
    flags: UCHAR;
    windows: USHORT;
    checksum: USHORT;
    urgentPointer: USHORT;
  end;
  PTCPHeader = ^TTCPHeader;


  TUDPHeader = packed record
    sourcePort:       USHORT;
    destinationPort:  USHORT;
    len:              USHORT;
    checksum:         USHORT;
  end;

  PUDPHeader = ^TUDPHeader;
  TICMPHeader = packed record
   IcmpType      : BYTE;
   IcmpCode      : BYTE;
   IcmpChecksum  : WORD;
   IcmpId        : WORD;
   IcmpSeq       : WORD;
   IcmpTimestamp : DWORD;
  end;
  PICMPHeader = ^TICMPHeader;

  IP_ADDRESS_STRING = record
    S: array [0..15] of Char;
  end;
  IP_MASK_STRING = IP_ADDRESS_STRING;
  PIP_MASK_STRING = ^IP_MASK_STRING;

  PIP_ADDR_STRING = ^IP_ADDR_STRING;
  IP_ADDR_STRING = record
    Next: PIP_ADDR_STRING;
    IpAddress: IP_ADDRESS_STRING;
    IpMask: IP_MASK_STRING;
    Context: DWORD;
  end;

  PIP_ADAPTER_INFO = ^IP_ADAPTER_INFO;
  IP_ADAPTER_INFO = record
    Next: PIP_ADAPTER_INFO;
    ComboIndex: DWORD;
    AdapterName: array [0..MAX_ADAPTER_NAME_LENGTH + 3] of Char;
    Description: array [0..MAX_ADAPTER_DESCRIPTION_LENGTH + 3] of Char;
    AddressLength: UINT;
    Address: array [0..MAX_ADAPTER_ADDRESS_LENGTH - 1] of BYTE;
    Index: DWORD;
    Type_: UINT;
    DhcpEnabled: UINT;
    CurrentIpAddress: PIP_ADDR_STRING;
    IpAddressList: IP_ADDR_STRING;
    GatewayList: IP_ADDR_STRING;
    DhcpServer: IP_ADDR_STRING;
    HaveWins: BOOL;
    PrimaryWinsServer: IP_ADDR_STRING;
    SecondaryWinsServer: IP_ADDR_STRING;
    LeaseObtained: time_t;
    LeaseExpires: time_t;
  end;
  
 //
 
 private
    { Private-Deklarationen }
    procedure ReadLanInterfaces;

//

function GetAdaptersInfo(pAdapterInfo: PIP_ADAPTER_INFO;
    var pOutBufLen: ULONG): DWORD; stdcall; external IPHelper;
    
//

procedure TForm1.ReadLanInterfaces;
var
  InterfaceInfo,
  TmpPointer: PIP_ADAPTER_INFO;
  IP: PIP_ADDR_STRING;
  Len: ULONG;
begin
  if GetAdaptersInfo(nil, Len) = ERROR_BUFFER_OVERFLOW then
  begin
    GetMem(InterfaceInfo, Len);
    try
      if GetAdaptersInfo(InterfaceInfo, Len) = ERROR_SUCCESS then
      begin
        TmpPointer := InterfaceInfo;
        repeat
          IP := @TmpPointer.IpAddressList;
          repeat
            ComboBox1.Items.Add(Format('%s - [%s]',
              [IP^.IpAddress.S, TmpPointer.Description]));
            IP := IP.Next;
          until IP = nil;
          TmpPointer := TmpPointer.Next;
        until TmpPointer = nil;
      end;
    finally
      FreeMem(InterfaceInfo);
    end;
  end;
  if ComboBox1.Items.Count = 0 then
  begin
    Exit;
  end
  else
    ComboBox1.ItemIndex := 0;
end;

Beispiel :

procedure TForm1.FormCreate(Sender: TObject);
begin
  ReadLanInterfaces;
end;