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1、实验二 IP数据包的捕获与解析网络0902 1.实验目的：掌握网络层的基本原理，通过编程实现网卡截取标准格式的IP包；解析IP数据包，了解IP包结构中个字段的含义与用途。2.实验原理：IP数据报结构：3. 实验环境平台：Windows、编程环境：VC 6.0、语言：C+4流程图及源代码#include #include #include #include#include #pragma comment(lib,ws2_32) /指定连接到网络应用和internet#define IO_RCVALL _WSAIOW(IOC_VENDOR,1) typedef struct IP_HEAD uni
2、on /定义联合 unsigned char Version; unsigned char HeadLen; ; unsigned char ServiceType; unsigned short TotalLen; unsigned short Identifier; union unsigned short Flags; unsigned short FragOffset; ; unsigned char TimeToLive; unsigned char Protocol; unsigned short HeadChecksum; unsigned int SourceAddr; uns
3、igned int DestinAddr; unsigned char Options; ip_head; /定义IP头部的数据结构void main(int argc,char *argv) using namespace std; ofstream outfile(C:logfile.txt,ios:out);if(argc!=2) coutendl请以下格式输入命令行:PackParse packet_sumendl; return; WSADATA WSAData; if(WSAStartup(MAKEWORD(2,2), &WSAData)!=0) coutendlWSASTartu
4、p初始化失败endl; return; SOCKET sock=socket(AF_INET,SOCK_RAW,IPPROTO_IP); /三个参分别为通信发生的区字段，套接字的类型，与IP协议if(sock=INVALID_SOCKET) coutendl创建Socket失败!endl; closesocket(sock); WSACleanup(); BOOL flag=TRUE; if(setsockopt(sock,IPPROTO_IP,IP_HDRINCL,(char *) &flag,sizeof(flag)=SOCKET_ERROR) coutendlsetsockopt操作失败
5、:WSAGetLastError()endl; closesocket(sock); WSACleanup(); char hostName128;/获取主机名 if(gethostname(hostName,100)=SOCKET_ERROR) coutendlgethostname操作失败:WSAGetLastError()endl; closesocket(sock); WSACleanup(); hostent *pHostIP; /获取本地IPif(pHostIP=gethostbyname(hostName)=NULL) coutendlgethostbyname操作失败:WSAG
6、etLastError()h_addr_list0; if(bind(sock,(PSOCKADDR)&host_addr,sizeof(host_addr)=SOCKET_ERROR) coutendlbind操作失败:WSAGetLastError()endl; closesocket(sock); /绑定网卡WSACleanup(); DWORD dwBufferLen10; DWORD dwBufferInLen=1; DWORD dwBytesReturned=0; if(WSAIoctl(sock , IO_RCVALL ,&dwBufferInLen , sizeof(dwBuf
7、ferInLen) , &dwBufferLen,sizeof(dwBufferLen),&dwBytesReturned,NULL,NULL)=SOCKET_ERROR) coutendlWSAIoctl操作失败:WSAGetLastError()endl; closesocket(sock); /将网卡设为混杂模式，以接受所有数据WSACleanup(); coutendl开始解析IP包:endl; char buffer65535; /设置缓冲区int packsum=atoi(argv1); /字符串转换为整形for(int i=0;i0) /四个参数分别是套接字描述符，缓冲区的地址，
8、缓冲区大小，附加标志 ip_head ip=*(ip_head *)buffer; cout-endl; cout版本:4)endl; /获取头部长度字段cout头部长度:(ip.HeadLen &0x0f)*4)endl; /获取头部长度字段cout服务类型:Priority5), Service1)&0x0f)endl; /优先级子域和TOS子域cout总长度:ip.TotalLenendl;/获取总长度字段 cout标识符:ip.Identifierendl;/获取标识字段 cout标志位:15)&0x01),DF= 14)&0x01),Mf=13)&0x01)endl; /获得标志字段
9、cout片偏移:(ip.FragOffset&0x1fff)endl; /获取分段偏移字段cout生存周期:(int)ip.TimeToLiveendl; /获取生存时间字段cout协议:Protocol(int)ip.Protocolendl; /获取协议字段cout头部校验和:ip.HeadChecksumendl; /获取头校验和字段cout原地址:inet_ntoa(*(in_addr *)&ip.SourceAddr)endl; /获取源IP地址字段cout目的IP地址:inet_ntoa(*(in_addr *)&ip.DestinAddr)endl; /获取目的IP地址字段out
10、file-endl; outfile版本:4)endl; outfile头部长度:(ip.HeadLen &0x0f)*4)endl; outfile服务类型:Priority5), Service1)&0x0f)endl; outfile总长度:ip.TotalLenendl; outfile标识符:ip.Identifierendl; outfile标志位:15)&0x01),DF= 14)&0x01),Mf=13)&0x01)endl; outfile片偏移:(ip.FragOffset&0x1fff)endl; outfile生存周期:(int)ip.TimeToLiveendl; outfile协议:Protocol(int)ip.Protocolendl; outfile头部校验和:ip.HeadChecksumendl; outfile原地址:inet_ntoa(*(in_addr *)&ip.SourceAddr)endl; outfile目的IP地址:inet_ntoa(*(in_addr *)&ip.DestinAddr)endl; closesocket(sock); WSACleanup(); 5.运行结果：
