James Marsh (James.Marsh at sandtechnology dot com) writes:

In my search for an ironclad method of finding the MAC address of the ethernet card of a system, I attempted the NetBIOS method as described in the FAQ, but found this to be unacceptable as some of our customers reportedly didn’t use [NetBIOS]. I passed over the RPC method, and found a solution in a page maintained by Stas Khirman and Raz Galili.... They describe a method of using the internal SNMP calls in Windows (NT, 95, and 2000 have worked for me) that are used by netstat and other windows utilities, but unfortunately provide no code example for finding the MAC code.

[Below is] a small program I’ve written up, so that hopefully other people won’t have to go through the same learning curve I did with SNMP. I will also attach a file, snmpapi.cpp, that was written by Stas Khirman and distributed on his web page.


snmpmac.cpp

#include <snmp.h>
#include <conio.h>
#include <stdio.h>

typedef BOOL(WINAPI * pSnmpExtensionInit) (
        IN DWORD dwTimeZeroReference,
        OUT HANDLE * hPollForTrapEvent,
        OUT AsnObjectIdentifier * supportedView);

typedef BOOL(WINAPI * pSnmpExtensionTrap) (
        OUT AsnObjectIdentifier * enterprise,
        OUT AsnInteger * genericTrap,
        OUT AsnInteger * specificTrap,
        OUT AsnTimeticks * timeStamp,
        OUT RFC1157VarBindList * variableBindings);

typedef BOOL(WINAPI * pSnmpExtensionQuery) (
        IN BYTE requestType,
        IN OUT RFC1157VarBindList * variableBindings,
        OUT AsnInteger * errorStatus,
        OUT AsnInteger * errorIndex);

typedef BOOL(WINAPI * pSnmpExtensionInitEx) (
        OUT AsnObjectIdentifier * supportedView);
    
void main()
{
    WSADATA WinsockData;
    if (WSAStartup(MAKEWORD(2, 0), &WinsockData) != 0) {
        fprintf(stderr, "This program requires Winsock 2.x!\n");
        return;
    }

    HINSTANCE m_hInst;
    pSnmpExtensionInit m_Init;
    pSnmpExtensionInitEx m_InitEx;
    pSnmpExtensionQuery m_Query;
    pSnmpExtensionTrap m_Trap;
    HANDLE PollForTrapEvent;
    AsnObjectIdentifier SupportedView;
    UINT OID_ifEntryType[] = {
        1, 3, 6, 1, 2, 1, 2, 2, 1, 3
    };
    UINT OID_ifEntryNum[] = {
        1, 3, 6, 1, 2, 1, 2, 1
    };
    UINT OID_ipMACEntAddr[] = {
        1, 3, 6, 1, 2, 1, 2, 2, 1, 6
    };                          //, 1 ,6 };
    AsnObjectIdentifier MIB_ifMACEntAddr =
        { sizeof(OID_ipMACEntAddr) / sizeof(UINT), OID_ipMACEntAddr };
    AsnObjectIdentifier MIB_ifEntryType = {
        sizeof(OID_ifEntryType) / sizeof(UINT), OID_ifEntryType
    };
    AsnObjectIdentifier MIB_ifEntryNum = {
        sizeof(OID_ifEntryNum) / sizeof(UINT), OID_ifEntryNum
    };
    RFC1157VarBindList varBindList;
    RFC1157VarBind varBind[2];
    AsnInteger errorStatus;
    AsnInteger errorIndex;
    AsnObjectIdentifier MIB_NULL = {
        0, 0
    };
    int ret;
    int dtmp;
    int i = 0, j = 0;
    BOOL found = FALSE;
    char TempEthernet[13];
    m_Init = NULL;
    m_InitEx = NULL;
    m_Query = NULL;
    m_Trap = NULL;

    /* Load the SNMP dll and get the addresses of the functions
       necessary */
    m_hInst = LoadLibrary("inetmib1.dll");
    if (m_hInst < (HINSTANCE) HINSTANCE_ERROR) {
        m_hInst = NULL;
        return;
    }
    m_Init =
        (pSnmpExtensionInit) GetProcAddress(m_hInst, "SnmpExtensionInit");
    m_InitEx =
        (pSnmpExtensionInitEx) GetProcAddress(m_hInst,
                                              "SnmpExtensionInitEx");
    m_Query =
        (pSnmpExtensionQuery) GetProcAddress(m_hInst,
                                             "SnmpExtensionQuery");
    m_Trap =
        (pSnmpExtensionTrap) GetProcAddress(m_hInst, "SnmpExtensionTrap");
    m_Init(GetTickCount(), &PollForTrapEvent, &SupportedView);

    /* Initialize the variable list to be retrieved by m_Query */
    varBindList.list = varBind;
    varBind[0].name = MIB_NULL;
    varBind[1].name = MIB_NULL;

    /* Copy in the OID to find the number of entries in the
       Inteface table */
    varBindList.len = 1;        /* Only retrieving one item */
    SNMP_oidcpy(&varBind[0].name, &MIB_ifEntryNum);
    ret =
        m_Query(ASN_RFC1157_GETNEXTREQUEST, &varBindList, &errorStatus,
                &errorIndex);
    printf("# of adapters in this system : %i\n",
           varBind[0].value.asnValue.number); varBindList.len = 2;

    /* Copy in the OID of ifType, the type of interface */
    SNMP_oidcpy(&varBind[0].name, &MIB_ifEntryType);

    /* Copy in the OID of ifPhysAddress, the address */
    SNMP_oidcpy(&varBind[1].name, &MIB_ifMACEntAddr);

    do {

        /* Submit the query.  Responses will be loaded into varBindList.
           We can expect this call to succeed a # of times corresponding
           to the # of adapters reported to be in the system */
        ret =
            m_Query(ASN_RFC1157_GETNEXTREQUEST, &varBindList, &errorStatus,
                    &errorIndex); if (!ret) ret = 1;

        else
            /* Confirm that the proper type has been returned */
            ret =
                SNMP_oidncmp(&varBind[0].name, &MIB_ifEntryType,
                             MIB_ifEntryType.idLength); if (!ret) {
            j++;
            dtmp = varBind[0].value.asnValue.number;
            printf("Interface #%i type : %i\n", j, dtmp);

            /* Type 6 describes ethernet interfaces */
            if (dtmp == 6) {

                /* Confirm that we have an address here */
                ret =
                    SNMP_oidncmp(&varBind[1].name, &MIB_ifMACEntAddr,
                                 MIB_ifMACEntAddr.idLength);
                if ((!ret)
                    && (varBind[1].value.asnValue.address.stream != NULL)) {
                    if (
                        (varBind[1].value.asnValue.address.stream[0] ==
                         0x44)
                        && (varBind[1].value.asnValue.address.stream[1] ==
                            0x45)
                        && (varBind[1].value.asnValue.address.stream[2] ==
                            0x53)
                        && (varBind[1].value.asnValue.address.stream[3] ==
                            0x54)
                        && (varBind[1].value.asnValue.address.stream[4] ==
                            0x00)) {

                        /* Ignore all dial-up networking adapters */
                        printf("Interface #%i is a DUN adapter\n", j);
                        continue;
                    }
                    if (
                        (varBind[1].value.asnValue.address.stream[0] ==
                         0x00)
                        && (varBind[1].value.asnValue.address.stream[1] ==
                            0x00)
                        && (varBind[1].value.asnValue.address.stream[2] ==
                            0x00)
                        && (varBind[1].value.asnValue.address.stream[3] ==
                            0x00)
                        && (varBind[1].value.asnValue.address.stream[4] ==
                            0x00)
                        && (varBind[1].value.asnValue.address.stream[5] ==
                            0x00)) {

                        /* Ignore NULL addresses returned by other network
                           interfaces */
                        printf("Interface #%i is a NULL address\n", j);
                        continue;
                    }
                    sprintf(TempEthernet, "%02x%02x%02x%02x%02x%02x",
                            varBind[1].value.asnValue.address.stream[0],
                            varBind[1].value.asnValue.address.stream[1],
                            varBind[1].value.asnValue.address.stream[2],
                            varBind[1].value.asnValue.address.stream[3],
                            varBind[1].value.asnValue.address.stream[4],
                            varBind[1].value.asnValue.address.stream[5]);
                    printf("MAC Address of interface #%i: %s\n", j,
                           TempEthernet);}
            }
        }
    } while (!ret);         /* Stop only on an error.  An error will occur
                               when we go exhaust the list of interfaces to
                               be examined */
    getch();

    /* Free the bindings */
    SNMP_FreeVarBind(&varBind[0]);
    SNMP_FreeVarBind(&varBind[1]);
}



snmpapi.cpp

/******************************************************************
*
*      Copyright (C) Stas Khirman 1998.  All rights reserved.         
*                                                                     
*       This program is distributed WITHOUT ANY WARRANTY
*
*******************************************************************/

/*************************************************
*     
*       Reproduction of SNMP.LIB and SNMPAPI.LIB base
*           functions
*
* Author: Stas Khirman (staskh@rocketmail.com)
*
*
* Free software: no warranty; use anywhere is ok; spread the      
* sources; note any modifications; share variations and           
* derivatives (including sending to staskh@rocketmail.com).       
*                                                                     
*
*************************************************/
#include <snmp.h>

SNMPAPI
SNMP_FUNC_TYPE
SnmpUtilOidCpy(
    OUT AsnObjectIdentifier *DstObjId,
    IN  AsnObjectIdentifier *SrcObjId
    )
{
  DstObjId->ids = (UINT *)GlobalAlloc(GMEM_ZEROINIT,SrcObjId->idLength * 
          sizeof(UINT));
  if(!DstObjId->ids){
    SetLastError(1);
    return 0;
  }

  memcpy(DstObjId->ids,SrcObjId->ids,SrcObjId->idLength*sizeof(UINT));
  DstObjId->idLength = SrcObjId->idLength;

  return 1;
}


VOID
SNMP_FUNC_TYPE
SnmpUtilOidFree(
    IN OUT AsnObjectIdentifier *ObjId
    )
{
  GlobalFree(ObjId->ids);
  ObjId->ids = 0;
  ObjId->idLength = 0;
}

SNMPAPI
SNMP_FUNC_TYPE
SnmpUtilOidNCmp(
    IN AsnObjectIdentifier *ObjIdA,
    IN AsnObjectIdentifier *ObjIdB,
    IN UINT                 Len
    )
{
  UINT CmpLen;
  UINT i;
  int  res;

  CmpLen = Len;
  if(ObjIdA->idLength < CmpLen)
    CmpLen = ObjIdA->idLength;
  if(ObjIdB->idLength < CmpLen)
    CmpLen = ObjIdB->idLength;

  for(i=0;i<CmpLen;i++){
    res = ObjIdA->ids[i] - ObjIdB->ids[i];
    if(res!=0)
      return res;
  }
  return 0;
}

VOID
SNMP_FUNC_TYPE
SnmpUtilVarBindFree(
    IN OUT RFC1157VarBind *VarBind
    )
{
  BYTE asnType;
  // free object name
  SnmpUtilOidFree(&VarBind->name);

  asnType = VarBind->value.asnType;

  if(asnType==ASN_OBJECTIDENTIFIER){
    SnmpUtilOidFree(&VarBind->value.asnValue.object);
  }
  else if(
        (asnType==ASN_OCTETSTRING) ||
        (asnType==ASN_RFC1155_IPADDRESS) ||
        (asnType==ASN_RFC1155_OPAQUE) ||
        (asnType==ASN_SEQUENCE)){
    if(VarBind->value.asnValue.string.dynamic){
      GlobalFree(VarBind->value.asnValue.string.stream);
    }
  }

  VarBind->value.asnType = ASN_NULL;

}



<< Get MAC Address, RPC Method
Get the Username >>
Updated Sun Jan 18 2015 04:24 MST   Go to my home page