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#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <string.h>
#include <arpa/inet.h>
#include <sys/select.h>
unsigned short cksum(unsigned short *addr, int len);
int main(int argc, char *argv[]) {
int sock;
char send_buf[400], src_ip[15], dst_ip[15], src_name[256];
struct ip *ip = (struct ip *)send_buf;
struct icmp *icmp = (struct icmp *)(ip + 1);
struct hostent *src_hp, *dst_hp;
struct sockaddr_in src, dst;
int on = 1;
memset(send_buf, 0, sizeof(send_buf));
if (argc < 2) {
printf("Need arg. I\n");
exit(EXIT_FAILURE);
}
/**if (getuid() == 0) {
fprintf(stderr, "Need to elevate\n");
exit(EXIT_FAILURE);
} **/
gethostname(src_name, sizeof(src_name));
printf("%s\n", src_name);
src_hp = gethostbyname(src_name);
ip->ip_src = (*(struct in_addr *)src_hp->h_addr_list[0]);
dst_hp = gethostbyname(argv[1]);
ip->ip_dst = (*(struct in_addr *)dst_hp->h_addr);
dst.sin_addr = (*(struct in_addr *)dst_hp->h_addr);
sprintf(src_ip, "%s", inet_ntoa(ip->ip_src));
sprintf(dst_ip, "%s", inet_ntoa(ip->ip_dst));
printf("Src: %s -- Dst: %s\n", src_ip, dst_ip);
// Create socket
sock = socket(AF_INET, SOCK_RAW, IPPROTO_RAW);
setsockopt(sock, IPPROTO_IP, IP_HDRINCL, &on, sizeof(on));
// IP Structure
ip->ip_v = 4;
ip->ip_hl = 5;
ip->ip_tos = 0;
ip->ip_len = htons(sizeof(send_buf));
ip->ip_id = htons(321);
ip->ip_off = htons(0);
ip->ip_ttl = 255;
ip->ip_p = IPPROTO_ICMP;
ip->ip_sum = 0;
// ICMP Structure
icmp->icmp_type = 2;
icmp->icmp_code = 0;
dst.sin_family = AF_INET;
ip->ip_sum = cksum((unsigned short *)send_buf, ip->ip_hl);
icmp->icmp_cksum = cksum((unsigned short *)icmp, sizeof(send_buf) - sizeof(struct icmp));
int dst_addr_len = sizeof(dst);
int bytes_sent;
if((bytes_sent = sendto(sock, send_buf, sizeof(send_buf), 0, (struct sockaddr *)&dst, dst_addr_len)) < 0) {
perror("send err");
fflush(stdout);
}
else {
printf("Sent %d bytes\n", bytes_sent);
}
}
unsigned short cksum(unsigned short *addr, int len) {
int nleft = len;
int sum = 0;
unsigned short *w = addr;
unsigned short answer = 0;
while (nleft > 1) {
sum += *w++;
nleft -= 2;
}
if (nleft == 1) {
*(unsigned char *)(&answer) = *(unsigned char *)w;
sum += answer;
}
sum = (sum >> 16) + (sum & 0xffff);
sum += (sum >> 16);
answer = ~sum;
return answer;
}
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