/* icmpmon might be lame piece, but is done more for experimenting
 * purposes rather than a something neato :)
 *
 * will show you all ICMP packets reaching your box, which could be useful 
 * in detecting attacks/portscans sometimes.
 * 
 *        comments: fygrave@tigerteam.net
 *        flames  : postmaster@localhost
 *         browsers: http://www.kalug.lug.net
 */


/* BSD compatibility */
#define __USE_BSD

#include <stdio.h>
#include <unistd.h>
#include <net/if.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>

char *icmppack[]={"ICMP ECHO REPLY","#1","#2","ICMP DEST UNREACHABLE",
  "ICMP SOURCE QUENCH","ICMP REDIRECT","#6","#7","ICMP ECHO",
  "ROUTER ADVERTISEMENT","ROUTER SOLICITATION","ICMP TIME EXCEEDED",
  "ICMP PARAM PROBLEM",
  "ICMP TIMESTAMP REQUEST","ICMP INFO REQUEST","ICMP INFO REPLY",
  "ICMP ADDRESS","ICMP ADDRESS REPLY"};
char *icmpunreach[]={"Network unreachable", "host unreachable", 
  "protocol unreachable", "port unreachable","need fragmentation",
  "source routed fialed","net denied","host denied","bad tos for net",
  "bad tos for host","filter denied","host precedence violation",
  "precedence cutoff"};
char *icmpredir[]={"Network redirect","host redirect","tos and net redir",
  "tos and host redir"};
char *icmptimex[]={"time exceed in transit","time exceed in reassembly"};






int sendpack( int s, u_long srcaddr, u_short srcport, u_long dstaddr, u_short dstport, u_char *packet) {

  return 0;
}

int main(argc,argv)
  int argc;
  char **argv;
{
  int rawfd,rd,rsize;
  int one=1;
  u_char buf[1024];
  struct sockaddr_in raddr;
  struct ip *ip;
  struct icmp *icmp;

if ((rawfd=socket(PF_INET,SOCK_RAW,IPPROTO_ICMP))<0) {
    perror("RawSocket:");
    exit(1);
  }
  if (setsockopt(rawfd,IPPROTO_IP,IP_HDRINCL,&one,sizeof(one))<0) {
    perror("SetSockOpt:");
    close(rawfd);
    exit(1);
  }


    
  printf("Listening to ICMP packets\n");
  for(;;) {
    fflush(stdout);
    if ((rd=recvfrom(rawfd,buf,1024,0,(struct sockaddr *)&raddr,&rsize))<0) break;
  ip=(struct ip *)buf;
  icmp=(struct icmp *)&buf[ip->ip_hl<<2];
  
  
  printf("%s packet from: %s ",icmppack[icmp->icmp_type],inet_ntoa(ip->ip_src));
/* details */
  switch(icmp->icmp_type) {
    case ICMP_UNREACH :
      printf("[%s]\n",icmpunreach[icmp->icmp_code]);
      break;
    case ICMP_REDIRECT :
      printf("[%s]\n",icmpredir[icmp->icmp_code]);
      break;
    case ICMP_TIMXCEED :
      printf("[%s]\n",icmptimex[icmp->icmp_code]);
      break;
    default: 
      printf("\n");
  }
  }
  close(rawfd);
  return 0;
}