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sniffer技术原理及应用(1)
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编辑：华夏媒体 作者：未知 来源：网络 时间：2006-07-29 总浏览量：1531 |
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corresponding code error
status = STATUS_INSUFFICIENT_RESOURCES;
}
if(ipFileObject != NULL)
ObDereferenceObject(ipFileObject);
ipFileObject = NULL;
ipDeviceObject = NULL;
}
else
return status;
}
//真正的过滤函数是这个，在最早的IRPdispatch里面传递的这个函数。
//这个函数就是系统传递了一个包头和包内容和包长度之类的东西，你可以在里面进行一些处理，
//假如你想让这个包通过的话，就返回PF_FORWARD，或者你不想让包通过的话，就返回PF_D
ROP就拦住了。是不是
//听起来很简单，
PF_FORWARD_ACTION cbFilterFunction(IN unsigned char *PacketHeader,IN
unsigned char *Packet, IN unsigned int PacketLength, IN unsigned int
RecvInterfaceIndex, IN unsigned int SendInterfaceIndex, IN unsigned long
RecvLinkNextHop, IN unsigned long SendLinkNextHop)
{
IPPacket *ipp;
TCPHeader *tcph;
UDPHeader *udph;
int countRule=0;
struct filterList *aux = first;
//we "extract" the ip Header
ipp=(IPPacket *)PacketHeader;
// dprintf("Source: %x\nDestination: %x\nProtocol: %d", ipp->ipSource,
ipp->ipDestination, ipp->ipProtocol);
//TCP -> protocol = 6
//we accept all packets of established connections
if(ipp->ipProtocol == 6)
{
tcph=(TCPHeader *)Packet;
// dprintf("FLAGS: %x\n", tcph->flags);
//if we havent the bit SYN activate, we pass the packets
if(!(tcph->flags & 0x02))
return PF_FORWARD;
}
//otherwise, we compare the packet with our rules
while(aux != NULL)
{
// dprintf("Comparing with Rule %d", countRule);
//if protocol is the same....
if(aux->ipf.protocol == 0 || ipp->ipProtocol ==
aux->ipf.protocol)
{
//we look in source Address
if(aux->ipf.sourceIp != 0 && (ipp->ipSource &
aux->ipf.sourceMask) != aux->ipf.sourceIp)
{
aux=aux->next;
countRule++;
continue;
}
// we look in destination address
if(aux->ipf.destinationIp != 0 && (ipp->ipDestination
& aux->ipf.destinationMask) != aux->ipf.destinationIp)
{
aux=aux->next;
countRule++;
continue;
}
//if we have a tcp packet, we look in ports
//tcp, protocol = 6
if(ipp->ipProtocol == 6)
{
if(aux->ipf.sourcePort == 0 ||
tcph->sourcePort == aux->ipf.sourcePort)
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