Home › Forums › Discussions › Support › STATIC FILTER using VB › Re: Re: STATIC FILTER using VB
October 23, 2013 at 7:06 pm
#7146
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.