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1- In m_ValidFields in static filters, there are only 3 predescribed values Data_Link_Layer_Valid, Networ_Link_Layer_Valid and Transport_Link_Layer_Valid which they are 1, 2 and 4 respectively.
But sometimes it is set to 0, especially to pass all packets. What does 0 means?It means that none of the validity fields is defined.
2- Why the network mask is 255.255.255.255? It was used when access to http://www.ntkernel.com website was blocked.
To block the particular IP address. If you use another mask you may block more than single IP.
3- How can I know how many packets been dropped?
All filters gather statistics of the packets for which filter did the action. You can query this statistics using API.
You have to start from PassThur sample.
For the authorized users you just pass packet through. When you detect HTTP GET request from unauthorized user you should generate HTTP redirect response packet. Since you pass all network packets through your application you can easily inspect/modify the traffic flow.
Current version f WInpkFilter installer does not recognize Windows 7, but you can install WinpkFilter drivers manually. It works just fine.
WinpkFilter 3.0.4 does not support this feature. Although it was added in the development version and available to WinpkFilter customers. The new added API allows to retrieve the information about currently active WAN connections. Structures for getting this information are defined as the following:
typedef
struct _RAS_LINK_INFO
{
#define RAS_LINK_BUFFER_LENGTH 1024
ULONG LinkSpeed; // Specifies the speed of the link, in units of 100 bps.
// Zero indicates no change from the speed returned when the protocol called NdisRequest with OID_GEN_LINK_SPEED.
ULONG MaximumTotalSize; // Specifies the maximum number of bytes per packet that the protocol can send over the network.
// Zero indicates no change from the value returned when the protocol called NdisRequest with OID_GEN_MAXIMUM_TOTAL_SIZE.
UCHAR RemoteAddress [ETHER_ADDR_LENGTH]; // Represents the address of the remote node on the link in Ethernet-style format. NDISWAN supplies this value.
UCHAR LocalAddress [ETHER_ADDR_LENGTH]; // Represents the protocol-determined context for indications on this link in Ethernet-style format.
ULONG ProtocolBufferLength;// Specifies the number of bytes in the buffer at ProtocolBuffer
UCHAR ProtocolBuffer [RAS_LINK_BUFFER_LENGTH]; // Containing protocol-specific information supplied by a higher-level component that makes connections through NDISWAN
// to the appropriate protocol(s). Maximum size is 600 bytes (on Windows Vista)
} RAS_LINK_INFO, *PRAS_LINK_INFO;
typedef
struct _RAS_LINKS
{
#define RAS_LINKS_MAX 256
ULONG nNumberOfLinks;
RAS_LINK_INFO RasLinks[RAS_LINKS_MAX];
} RAS_LINKS, *PRAS_LINKS;Thanks. Happy New Year to you too!
I’ve been a bit overloaded last time. Need to find some free time to complete the new release. Hopefully in March.
You can use IP helper API to query current active connections table and match your packet against this table using IP address and port information you have. Since Windows XP connections table contains process ID. Another way is using LSP or TDI filter driver.
Most probably there is something wrong with structures definitions. Or you may be trying to process non TCP packet.
Under “using MSTCP default behavior” I mean that you may modify incoming/outgoing packets and let TCP/IP route them. Like in case of NAT, WIndows TCP/IP stack by default routes packets coming from LAN into default gateway interface (connected to the Internet). To implement NAT you can only capture packets from external (Internet connected) network interface:
– For outgoing packets change source IP address to Internet interface assigned one and port allocated/according NAT table
-For incoming packets change destination IP/port according NAT tableThis way you use Microsoft TCP/IP routing and don’t have to implement it on your own.
Is that clear now?
