Ponizszy kod ma za zadanie budowac pakiet eth+ip+tcp lecz niestety naglowek eth nie jest dodawany.
Czekam na wasze propozycje co do poprawy tego zrodla.

#define __USE_BSD   /* use bsd'ish ip header */
#include <sys/socket.h> /* these headers are for a Linux system, but */
#include <netinet/in.h> /* the names on other systems are easy to guess.. */
#include <netinet/ip.h>
#include <net/ethernet.h>
#define __FAVOR_BSD /* use bsd'ish tcp header */
#include <netinet/tcp.h>
#include <unistd.h>

#define P 25        /* lets flood the sendmail port */

unsigned short      /* this function generates header checksums */
csum (unsigned short *buf, int nwords)
{
  unsigned long sum;
  for (sum = 0; nwords > 0; nwords--)
    sum += *buf++;
  sum = (sum >> 16) + (sum & 0xffff);
  sum += (sum >> 16);
  return ~sum;
}

int main (void)
{
  int s = socket (PF_INET, SOCK_RAW, htons(ETH_P_ALL)); 
  int packetsize = sizeof(struct ether_header) + sizeof(struct iphdr) + sizeof(struct tcphdr);
  char datagram[packetsize];
  struct ether_header *eth = (struct ether_header *) datagram;
  struct ip *iph = (struct ip*) (datagram + sizeof(struct ether_header));
  struct tcphdr *tcph = (struct tcphdr*) 
  (datagram + sizeof(struct ether_header) +sizeof(struct ip));

  struct sockaddr_in sin;           
  sin.sin_family = AF_INET;
  sin.sin_port = htons (P);
  sin.sin_addr.s_addr = inet_addr ("2.2.2.2");

  memset (datagram, 0, packetsize); 
  char smac[]="11:11:11:11:11:11";
  char dmac[]="22:22:22:22:22:22";

  memcpy(eth->ether_dhost,(u_char *)ether_aton(dmac),ETH_ALEN); // Destination MAC
  memcpy(eth->ether_shost,(u_char *)ether_aton(smac),ETH_ALEN); // Source MAC
  eth->ether_type = htons(ETHERTYPE_IP); // IP Protokoll

  iph->ip_hl = 5;
  iph->ip_v = 4;
  iph->ip_tos = 0;
  iph->ip_len = sizeof(struct ether_header)+sizeof (struct ip) + sizeof (struct tcphdr);    
  iph->ip_id = htonl (54321);   
  iph->ip_off = 0;
  iph->ip_ttl = 255;
  iph->ip_p = 6;
  iph->ip_sum = 0;      
  iph->ip_src.s_addr = inet_addr ("1.1.1.1"); 
  iph->ip_dst.s_addr = sin.sin_addr.s_addr;

  tcph->th_sport = htons (1234);    
  tcph->th_dport = htons (P);
  tcph->th_seq = random ();
  tcph->th_ack = 0;
  tcph->th_x2 = 0;
  tcph->th_off = 0;     
  tcph->th_flags = TH_SYN;  
  tcph->th_win = htonl (65535); 
  tcph->th_sum = 0;

  tcph->th_urp = 0;

  iph->ip_sum = csum ((unsigned short *) datagram, iph->ip_len >> 1);

  {             
    int one = 1;
    const int *val = &one;
    if (setsockopt (s, IPPROTO_IP, IP_HDRINCL, val, sizeof (one)) < 0)
      printf ("Warning: Cannot set HDRINCL!\n");
  }

      if (sendto (s,        
          datagram, 
          iph->ip_len,  
          0,        
          (struct sockaddr *) &sin, 
          sizeof (sin)) < 0)        
    printf ("error\n");
      else
    printf ("WYSLALEM \n");

  return 0;
}