在做大学最后的毕业设计了,无线局域网络远程安全监控策略
那么抓包是这个系统设计的基础
以前一直都是知道用winpcap的,现在网上搜了一下,有用C#封装好了的,很好用
下面是其中的几个用法
这个类库作者的主页:http://www.tamirgal.com/home/default.aspx
PcapOpen()有下面几个方法
- PcapOpen()
- PcapOpen(bool promiscuous_mode)
- PcapOpen(bool promiscuous_mode, int read_timeout)
promiscuous_mode:在普通的抓取模式下,我们只抓取那些目的地为目标网络的包,而处于promiscuous_mode时,则抓取所有的包,包括转发的包.通常我们都是开启这种模式的
下面是示例:
//Extract a device from the list
PcapDevice device = devices[i];
//Register our handler function to the
//'packet arrival' event
device.PcapOnPacketArrival +=
new SharpPcap.PacketArrivalEvent(device_PcapOnPacketArrival);
//Open the device for capturing
//true -- means promiscuous mode
//1000 -- means a read wait of 1000ms
device.PcapOpen();
Console.WriteLine(
"-- Listenning on {0}, hit 'Enter' to stop...",
device.PcapDescription);
//Start the capturing process
device.PcapStartCapture();
//Wait for 'Enter' from the user.
Console.ReadLine();
//Stop the capturing process
device.PcapStopCapture();
//Close the pcap device
device.PcapClose();
PcapStartCapture()对应PcapStopCapture()
使用PcapCapture(int packetCount)时我们可以使用SharpPcap.INFINITE,来达到持续抓包的功能
Note:通常CRC的数据是不在数据包的中的,因为通常错误的CRC包会被自动丢弃.
上面的需要注册一个event handle,这在很多时候是不可行的,所以我们推荐使用下面这个方法PcapGetNextPacket()
//Extract a device from the list
PcapDevice device = devices[i];
//Open the device for capturing
//true -- means promiscuous mode
//1000 -- means a read wait of 1000ms
device.PcapOpen();
Console.WriteLine();
Console.WriteLine("-- Listenning on {0}...",
device.PcapDescription);
Packet packet = null;
//Keep capture packets using PcapGetNextPacket()
while( (packet=device.PcapGetNextPacket()) != null )
{
// Prints the time and length of each received packet
DateTime time = packet.PcapHeader.Date;
int len = packet.PcapHeader.PacketLength;
Console.WriteLine("{0}:{1}:{2},{3} Len={4}",
time.Hour, time.Minute, time.Second,
time.Millisecond, len);
}
//Close the pcap device
device.PcapClose();
Console.WriteLine("-- Capture stopped, device closed.");
PcapSetFilter() 设置过滤条件
string filter = "ip and tcp";
device.PcapSetFilter( filter );
下面这个例子通过抓取TCP包,输出他们的时间,长度,源IP,源端口,目的IP,目的端口
/// <SUMMARY>
/// Prints the time, length, src ip,
/// src port, dst ip and dst port
/// for each TCP/IP packet received on the network
/// </SUMMARY>
private static void device_PcapOnPacketArrival(
object sender, Packet packet)
{
if(packet is TCPPacket)
{
DateTime time = packet.Timeval.Date;
int len = packet.PcapHeader.len;
TCPPacket tcp = (TCPPacket)packet;
string srcIp = tcp.SourceAddress;
string dstIp = tcp.DestinationAddress;
int srcPort = tcp.SourcePort;
int dstPort = tcp.DestinationPort;
Console.WriteLine("{0}:{1}:{2},
{} Len={} {}:{} -> {}:{}",
time.Hour, time.Minute, time.Second,
time.Millisecond, len, srcIp, srcPort,
dstIp, dstPort);
}
}