Re: OID_xxx_PERMANENT_ADDRESS does NOT work!! - Network Adpaters and Cisco VPN
- From: soviet_bloke@xxxxxxxxxxx
- Date: 6 Nov 2006 19:58:50 -0800
Graem,
I think that Pavel's suggestion about "hijacked NIC" is perfectly
reasonable (although the very term "hijacked" does not seem to be
appropriate under these circumstances. More on this below).
First of all, by sending some certain OIDs to the target NIC a caller
may change its configuration, and, if NICs configuration changes while
VPN adapter is around, this change may simply break its operations.
Therefore, VPN adapter wants to know what's going on, so that it
monitors (and, apparently, tampers with) IOCTLs that get send to
stand-alone device that miniport driver has registered.
Second, VPN may block access to physical NICs simply for security
reasons - it may want
to make sure that *ABSOLUTELY* all Internet traffic from/to the target
machine goes via VPN. Therefore, it makes sure that, from the client's
perspective, VPN adapter is the only
adapter that is installed on the target machine. If VPN is used for
accessing a corporate network, such approach is more than reasonable
In other words, you should not be surprized at all
Anton Bassov
Graem Rucker wrote:
From the previous thread: "PCI Network Adpaters & PnpInstanceID", I was told
that I should enumerate my network adapters (which I am doing fine now) and
DeviceIoControl each for its permanent address.
Sounds good in theory - BUT - here is the problem.:
For a given network adapter on a machine - I CreateFile using its GUID, then
gets its supported OID_xxx_PERMANENT_ADDRESS, and call DeviceIoControl for
that.
When a Cisco VPN is not connected - it seems to return the correct MAC
address (of the card). However - when the VPN is connected - it returns the
MAC address of the VPN! This doesnt make sense (to me) because - I have
carefully triple checked that in fact the GUID used for the CrateFile
operation is the exact same in both cases and is the GUID for the physical
network card.
What the hell is happening here?
Here is the code that sends the IO Control calls:
{
AnsiString nicFile = Format("\\\\.\\%s",
ARRAYOFCONST((pNICNames->Strings[i])));
// Open the device for reading
HANDLE hDevice = CreateFile(nicFile.c_str(), 0, FILE_SHARE_READ,
NULL, OPEN_EXISTING, 0,
INVALID_HANDLE_VALUE);
if (hDevice != INVALID_HANDLE_VALUE)
{
try
{
NDIS_OID OidCode = OID_GEN_SUPPORTED_LIST;
DWORD OidData[4096];
ZeroMemory(OidData, sizeof(OidData));
ULONG ulBytesReturned = 0;
bool bResult = (bool) DeviceIoControl(
hDevice,
IOCTL_NDIS_QUERY_GLOBAL_STATS,
&OidCode,
sizeof(NDIS_OID),
OidData,
sizeof(OidData),
&ulBytesReturned,
NULL );
if (!bResult)
{
#ifdef _DEBUG
FormatOutputMessage();
#endif
}
else
{
// we got the supported list - lets find which
protocol it supports for OID_xxx_PERMANENT_ADDRESS
OidCode = 0;
for (int n = 0; n < ulBytesReturned/4; ++n)
{
if(OidData[n] == OID_802_3_PERMANENT_ADDRESS) //
ethernet
{
OidCode = OID_802_3_PERMANENT_ADDRESS;
break;
}
else if (OidData[n] ==
OID_802_5_PERMANENT_ADDRESS) // token ring
{
OidCode = OID_802_5_PERMANENT_ADDRESS;
break;
}
else if (OidData[n] ==
OID_WAN_PERMANENT_ADDRESS) //wan
{
OidCode = OID_WAN_PERMANENT_ADDRESS;
break;
}
else if (OidData[n] ==
OID_ARCNET_PERMANENT_ADDRESS) // arcnet
{
OidCode = OID_ARCNET_PERMANENT_ADDRESS;
break;
}
}
if (0 != OidCode)
{
// we got a protocol - get the perm address now.
ZeroMemory(OidData, sizeof(OidData));
ulBytesReturned = 0;
bResult = (bool) DeviceIoControl(
hDevice,
IOCTL_NDIS_QUERY_GLOBAL_STATS,
&OidCode,
sizeof(NDIS_OID),
OidData,
sizeof(OidData),
&ulBytesReturned,
NULL );
if (!bResult)
{
#ifdef _DEBUG
FormatOutputMessage();
#endif
}
else
{
#ifdef _DEBUG
AnsiString test87645 = "Got MAC address
for: " + pNICNames->Strings[i];
OutputDebugString(test87645.c_str());
#endif
// we think we got the address.
if (6 == ulBytesReturned)
{
// we got it
AMacAddress.SetLength((ulBytesReturned *
3) - 1);
char *ptr = AMacAddress.c_str();
LPBYTE MACData = (LPBYTE)OidData;
sprintf(ptr, "%02X", MACData[0]);
ptr += 2;
for(DWORD i = 1; i < 6; ++i)
{
sprintf(ptr, ":%02X", MACData[i]);
ptr += 3;
}
}
break;
}
}
}
}
__finally
{
// Close the device
CloseHandle(hDevice);
}
}
}
.
- References:
- OID_xxx_PERMANENT_ADDRESS does NOT work!! - Network Adpaters and Cisco VPN
- From: Graem Rucker
- OID_xxx_PERMANENT_ADDRESS does NOT work!! - Network Adpaters and Cisco VPN
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