[Vadim Smirnov]

The problem caused by -DUNICODE compiler switch. If you want your project to use UNICODE then you have to recompile ndisapi.dll as UNICODE either. For backward compatibility with earlier versions of Windows ndisapi.dll distributed within WinpkFilter package is built as multibyte.

[Vadim Smirnov]

ReadPackets/SendPacketsToXXX were added to reduce number of user/kernel context switches and thus increase the performance.

The easiest approach would be processing packets one by one in one thread, however, if you use multiply threads for and still want to take an advantage of SendPacketsToXXX API calls I would keep an internal queue of packets for each network interface which are ready to send to driver (actually two queues, one for outgoing and one for incoming packets). Queue should be sent to driver on one of two events:
1) Queue size reached its “immediate sent” size
2) Timeout occurs

Size and timeout should be dynamic parameters adjusted depending on the amount of packets you get from the driver. E.g. the faster you read packets from the driver the less the timeout.

[Vadim Smirnov]

Yes, Windows 2000 is supported, although the driver installed for that OS is different from the one used for XP or Vista and later.

If you can collect the crash dump (kernel or full) we could check what has happened. I suspect this could we a sort of software conflict if you have firewalling/AV software installed.

[Vadim Smirnov]

Hi,

I nearly have no experience in VB, but there is a C sample filter.cpp which has a scenario to redirect only DNS packets for processing by WinpkFilter application.

This sample scenario can be easily modified to intercept only DNS queries destined to local DNS server this way:

pFilters->m_TableSize = 2;





// 1. Incoming DNS requests filter: REDIRECT IN UDP packets with destination PORT 53

// Common values

pFilters->m_StaticFilters[0].m_Adapter.QuadPart = 0; // applied to all adapters

pFilters->m_StaticFilters[0].m_ValidFields = NETWORK_LAYER_VALID | TRANSPORT_LAYER_VALID;

pFilters->m_StaticFilters[0].m_FilterAction = FILTER_PACKET_REDIRECT;

pFilters->m_StaticFilters[0].m_dwDirectionFlags = PACKET_FLAG_ON_RECEIVE;



// Network layer filter

pFilters->m_StaticFilters[0].m_NetworkFilter.m_dwUnionSelector = IPV4;

pFilters->m_StaticFilters[0].m_NetworkFilter.m_IPv4.m_ValidFields = IP_V4_FILTER_PROTOCOL;

pFilters->m_StaticFilters[0].m_NetworkFilter.m_IPv4.m_Protocol = IPPROTO_UDP;



// Transport layer filter

pFilters->m_StaticFilters[0].m_TransportFilter.m_dwUnionSelector = TCPUDP;

pFilters->m_StaticFilters[0].m_TransportFilter.m_TcpUdp.m_ValidFields = TCPUDP_SRC_PORT;

pFilters->m_StaticFilters[0].m_TransportFilter.m_TcpUdp.m_DestPort.m_StartRange = 53; // DNS

pFilters->m_StaticFilters[0].m_TransportFilter.m_TcpUdp.m_DestPort.m_EndRange = 53;



//***************************************************************************************

// 2. Pass all packets (skipped by previous filters) without processing in user mode

// Common values

pFilters->m_StaticFilters[1].m_Adapter.QuadPart = 0; // applied to all adapters

pFilters->m_StaticFilters[1].m_ValidFields = 0;

pFilters->m_StaticFilters[1].m_FilterAction = FILTER_PACKET_PASS;

pFilters->m_StaticFilters[1].m_dwDirectionFlags = PACKET_FLAG_ON_RECEIVE | PACKET_FLAG_ON_SEND;



break;

The filter you showed in your initial post should select only outgoing DNS queries, not incoming ones.

[Vadim Smirnov]

From what I can see WinpkFilter is installed and works. An example these are definitely your ICMP PING packets:

9 – MSTCP –> Interface
Packet size = 74
Source MAC: C0A8010CC0A8
Destination MAC: 000080016CC3

8 – Interface –> MSTCP
Packet size = 74
Source MAC: C0A80102C0A8
Destination MAC: 0000800164E8

But for some reason packet is not correctly parsed by passthru sample. This may be caused by version mismatch between driver and passthru application (INTERMEDIATE_BUFFER structure was changed several times in last versions and it is important to use driver and application built on the same common.h).

[Vadim Smirnov]

If you look at the filter.cpp sample you can find the scenario which redirects only DNS packets to user mode and passes any other packets. Filters are defined as the following:

//**************************************************************************************

// 1. Outgoing DNS requests filter: REDIRECT OUT UDP packets with destination PORT 53

// Common values

pFilters->m_StaticFilters[0].m_Adapter.QuadPart = 0; // applied to all adapters

pFilters->m_StaticFilters[0].m_ValidFields = NETWORK_LAYER_VALID | TRANSPORT_LAYER_VALID;

pFilters->m_StaticFilters[0].m_FilterAction = FILTER_PACKET_REDIRECT;

pFilters->m_StaticFilters[0].m_dwDirectionFlags = PACKET_FLAG_ON_SEND;



// Network layer filter

pFilters->m_StaticFilters[0].m_NetworkFilter.m_dwUnionSelector = IPV4;

pFilters->m_StaticFilters[0].m_NetworkFilter.m_IPv4.m_ValidFields = IP_V4_FILTER_PROTOCOL;

pFilters->m_StaticFilters[0].m_NetworkFilter.m_IPv4.m_Protocol = IPPROTO_UDP;



// Transport layer filter

pFilters->m_StaticFilters[0].m_TransportFilter.m_dwUnionSelector = TCPUDP;

pFilters->m_StaticFilters[0].m_TransportFilter.m_TcpUdp.m_ValidFields = TCPUDP_DEST_PORT;

pFilters->m_StaticFilters[0].m_TransportFilter.m_TcpUdp.m_DestPort.m_StartRange = 53; // DNS

pFilters->m_StaticFilters[0].m_TransportFilter.m_TcpUdp.m_DestPort.m_EndRange = 53;



//****************************************************************************************

// 2. Incoming DNS responses filter: REDIRECT IN UDP packets with source PORT 53

// Common values

pFilters->m_StaticFilters[1].m_Adapter.QuadPart = 0; // applied to all adapters

pFilters->m_StaticFilters[1].m_ValidFields = NETWORK_LAYER_VALID | TRANSPORT_LAYER_VALID;

pFilters->m_StaticFilters[1].m_FilterAction = FILTER_PACKET_REDIRECT;

pFilters->m_StaticFilters[1].m_dwDirectionFlags = PACKET_FLAG_ON_RECEIVE;



// Network layer filter

pFilters->m_StaticFilters[1].m_NetworkFilter.m_dwUnionSelector = IPV4;

pFilters->m_StaticFilters[1].m_NetworkFilter.m_IPv4.m_ValidFields = IP_V4_FILTER_PROTOCOL;

pFilters->m_StaticFilters[1].m_NetworkFilter.m_IPv4.m_Protocol = IPPROTO_UDP;



// Transport layer filter

pFilters->m_StaticFilters[1].m_TransportFilter.m_dwUnionSelector = TCPUDP;

pFilters->m_StaticFilters[1].m_TransportFilter.m_TcpUdp.m_ValidFields = TCPUDP_SRC_PORT;

pFilters->m_StaticFilters[1].m_TransportFilter.m_TcpUdp.m_SourcePort.m_StartRange = 53; // DNS

pFilters->m_StaticFilters[1].m_TransportFilter.m_TcpUdp.m_SourcePort.m_EndRange = 53;



//***************************************************************************************

// 3. Pass all packets (skipped by previous filters) without processing in user mode

// Common values

pFilters->m_StaticFilters[2].m_Adapter.QuadPart = 0; // applied to all adapters

pFilters->m_StaticFilters[2].m_ValidFields = 0;

pFilters->m_StaticFilters[2].m_FilterAction = FILTER_PACKET_PASS;

pFilters->m_StaticFilters[2].m_dwDirectionFlags = PACKET_FLAG_ON_RECEIVE | PACKET_FLAG_ON_SEND;



break;

Does this sample work for you?

[Vadim Smirnov]

Hi Ghita,

I can’t see the filters you have set, but I suspect that your filters for blocking TCP/UDP may be destination IP/MAC address specfic and therefore broadcast/multicast packets get passed (they have special broadcast/multicast MAC and IP adresses).

Hope it helps…

[Vadim Smirnov]

Thank you for the update. I’m glad that you have resolved the issue.

[Vadim Smirnov]

Could you provide more details?
1) ListAdapters output.
2) PassThru output. For this test ping one of other notebooks.
3) IPCONFIG output.

We are not aware about any issues with Windows 7, so it must be something about your configuration or usage.

[Vadim Smirnov]

To resolve an issue with DNS you can change all your filters from blocking to redirect and check filter ID in the DNS packets. So you can identify filter which selects DNS packets.

[Vadim Smirnov]

From what I can see filter 2 is supposed to block incoming packets on local port 80. If this is what you want to do and still incoming packets on port port 80 are not blocked then there is only one possibility – these packets are passed by filter 1.

[Vadim Smirnov]

I don’t have the filters code under hand at the moment but for the second filter I would add that it should be applied to TCP protocol.

[Vadim Smirnov]

Please clarify, are using an application build on top of WinpkFilter driver and this application reports that driver is missing?

[Vadim Smirnov]

Windows Packet Filter Kit 3.1.3 released:
– Changed approach to disable TCP task offload in NDIS LWF. Previous method had some known issues.

If you are eligible for a free update, please send the following details to [email protected] tо receive an update instruction:

1) Your order ID.
2) An approximate date of purchasing.

[Vadim Smirnov]

I’m not familier with IPSECVPN software you use, but yes, there are two possibilities:

1) IPSEC driver above WinpkFilter: in this case instead normal TCP/IP packets (all or only part of them depending on IPSEC policy) you intercept encrypted IPSEC packets. I’m not sure how your WinpkFilter software would deal with these packets (tries to tunnel or ignores).
2) IPSEC driver below WinpkFilter: in this case your UDP tunnel packets can be encrypted by IPSEC driver (depending on the policy).

I would check what packet you get in your WinpkFilter software and check what packet go out on the network media with network sniffer to discover the details.

[Author]

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