實驗二 IP數據包的捕獲與解析網絡0902 1.實驗目的：掌握網絡層的基本原理，通過編程實現網卡截取標準格式的IP包；解析IP數據包，了解IP包結構中個字段的含義與用途。2.實驗原理：IP數據報結構：3. 實驗環境平臺：Windows、編程環境：VC 6.0、語言：C+4流程圖及源代碼#include #include #include #include#include #pragma comment(lib,ws2_32) /指定連接到網絡應用和internet#define IO_RCVALL _WSAIOW(IOC_VENDOR,1) typedef struct IP_HEAD union /定義聯合 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; unsigned int DestinAddr; unsigned char Options; ip_head; /定義IP頭部的數據結構void main(int argc,char *argv) using namespace std; ofstream outfile(C:logfile.txt,ios:out);if(argc!=2) coutendl請以下格式輸入命令行:PackParse packet_sumendl; return; WSADATA WSAData; if(WSAStartup(MAKEWORD(2,2), &WSAData)!=0) coutendlWSASTartup初始化失敗endl; return; SOCKET sock=socket(AF_INET,SOCK_RAW,IPPROTO_IP); /三個參分別為通信發生的區字段，套接字的類型，與IP協議if(sock=INVALID_SOCKET) coutendl創建Socket失敗!endl; closesocket(sock); WSACleanup(); BOOL flag=TRUE; if(setsockopt(sock,IPPROTO_IP,IP_HDRINCL,(char *) &flag,sizeof(flag)=SOCKET_ERROR) coutendlsetsockopt操作失敗:WSAGetLastError()endl; closesocket(sock); WSACleanup(); char hostName128;/獲取主機名 if(gethostname(hostName,100)=SOCKET_ERROR) coutendlgethostname操作失敗:WSAGetLastError()endl; closesocket(sock); WSACleanup(); hostent *pHostIP; /獲取本地IPif(pHostIP=gethostbyname(hostName)=NULL) coutendlgethostbyname操作失敗:WSAGetLastError()h_addr_list0; if(bind(sock,(PSOCKADDR)&host_addr,sizeof(host_addr)=SOCKET_ERROR) coutendlbind操作失敗:WSAGetLastError()endl; closesocket(sock); /綁定網卡WSACleanup(); DWORD dwBufferLen10; DWORD dwBufferInLen=1; DWORD dwBytesReturned=0; if(WSAIoctl(sock , IO_RCVALL ,&dwBufferInLen , sizeof(dwBufferInLen) , &dwBufferLen,sizeof(dwBufferLen),&dwBytesReturned,NULL,NULL)=SOCKET_ERROR) coutendlWSAIoctl操作失敗:WSAGetLastError()endl; closesocket(sock); /將網卡設為混雜模式，以接受所有數據WSACleanup(); coutendl開始解析IP包:endl; char buffer65535; /設置緩沖區int packsum=atoi(argv1); /字符串轉換為整形for(int i=0;i0) /四個參數分別是套接字描述符，緩沖區的地址，緩沖區大小，附加標志 ip_head ip=*(ip_head *)buffer; cout-endl; cout版本:4)endl; /獲取頭部長度字段cout頭部長度:(ip.HeadLen &0x0f)*4)endl; /獲取頭部長度字段cout服務類型:Priority5), Service1)&0x0f)endl; /優先級子域和TOS子域cout總長度:ip.TotalLenendl;/獲取總長度字段 cout標識符:ip.Identifierendl;/獲取標識字段 cout標志位:15)&0x01),DF= 14)&0x01),Mf=13)&0x01)endl; /獲得標志字段cout片偏移:(ip.FragOffset&0x1fff)endl; /獲取分段偏移字段cout生存周期:(int)ip.TimeToLiveendl; /獲取生存時間字段cout協議:Protocol(int)ip.Protocolendl; /獲取協議字段cout頭部校驗和:ip.HeadChecksumendl; /獲取頭校驗和字段cout原地址:inet_ntoa(*(in_addr *)&ip.SourceAddr)endl; /獲取源IP地址字段cout目的IP地址:inet_ntoa(*(in_addr *)&ip.DestinAddr)endl; /獲取目的IP地址字段outfile-endl; outfile版本:4)endl; outfile頭部長度:(ip.HeadLen &0x0f)*4)endl; outfile服務類型:Priority5), Service1)&0x0f)endl; outfile總長度:ip.TotalLenendl; outfile標識符:ip.Identifierendl; outfile標志位: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協議:Protocol(int)ip.Protocolendl; outfile頭部校驗和:ip.HeadChec