linux实现的两台机器之间的网络抓包程序

#include <stdio.h> #include <unistd.h> #include <sys/socket.h> #include <sys/types.h> #include <linux/if_ether.h> #include <linux/in.h> #define BUFFER_MAX 2048 int main(int argc, char *argv[]) { int sock, n_read, proto; char *version, *code; char buffer[BUFFER_MAX]; char *ethhead, *iphead, *tcphead, *checksum,*idetification,*sequnce,*data, *udphead, *icmphead, *p; if((sock = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_IP))) < 0) { fprintf(stdout, "create socket error\n"); return -1; } while(1) { n_read = recvfrom(sock, buffer, 2048, 0, NULL, NULL); /* 14 6(dest)+6(source)+2(type or length) + 20 ip header + 8 icmp,tcp or udp header = 42 */ if(n_read < 42) { fprintf(stdout, "Incomplete header, packet corrupt\n"); continue; } ethhead = buffer; p = ethhead; int n = 0XFF; printf("MAC: %.2X:%02X:%02X:%02X:%02X:%02X==>" "%.2X:%.2X:%.2X:%.2X:%.2X:%.2X\n", p[6]&n, p[7]&n, p[8]&n, p[9]&n, p[10]&n, p[11]&n, p[0]&n, p[1]&n, p[2]&n,p[3]&n, p[4]&n, p[5]&n); iphead = ethhead + 14; p = iphead + 12; version=iphead+20;//版本号 code=version+1;//code checksum=code+1;//首部检验和 idetification=checksum+2;//标识符 sequnce=idetification+2;//序号 data=sequnce+2;//数据 printf("IP: %d.%d.%d.%d => %d.%d.%d.%d\n", p[0]&0XFF, p[1]&0XFF, p[2]&0XFF, p[3]&0XFF, p[4]&0XFF, p[5]&0XFF, p[6]&0XFF, p[7]&0XFF); proto = (iphead + 9)[0]; p = iphead + 20; printf("Protocol: "); switch(proto) { case IPPROTO_ICMP: printf("ICMP\n");break; case IPPROTO_IGMP: printf("IGMP\n");break; case IPPROTO_IPIP: printf("IPIP\n");break; case IPPROTO_TCP : case IPPROTO_UDP : printf("%s,", proto == IPPROTO_TCP ? "TCP": "UDP"); printf("source port: %u,",(p[0]<<8)&0XFF00 | p[1]&0XFF); printf("dest port: %u\n", (p[2]<<8)&0XFF00 | p[3]&0XFF); break; case IPPROTO_RAW : printf("RAW\n");break; default:printf("Unkown, please query in include/linux/in.h\n"); } printf("version: %.2x\n",version[0]); printf("code: %.2x\n",code[0]); printf("checksum: %.2x %.2x\n", checksum[0]&n,checksum[1]&n); printf("idetification: %.2x %.2x\n",idetification[0]&n,idetification[1]&n); printf("sequnce : %.2x %.2x\n",sequnce[0]&n,sequnce[1]&n); printf("data: %.2x %.2x %.2x %.2x %.2x %.2x %.2x\n", data[0]&n,data[1]&n,data[2]&n,data[3]&n,data[4]&n,data[5]&n,data[6]&n); } }