1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
|
#include <netinet/ip.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
void print_as_bytes (unsigned char* buff, ssize_t length)
{
for (ssize_t i = 0; i < length; i++, buff++)
printf ("%.2x ", *buff);
}
int main()
{
int sockfd = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
if (sockfd < 0) {
fprintf(stderr, "socket error: %s\n", strerror(errno));
return EXIT_FAILURE;
}
for (;;) {
struct sockaddr_in sender;
socklen_t sender_len = sizeof(sender);
u_int8_t buffer[IP_MAXPACKET];
ssize_t packet_len = recvfrom (sockfd, buffer, IP_MAXPACKET, 0, (struct sockaddr*)&sender, &sender_len);
if (packet_len < 0) {
fprintf(stderr, "recvfrom error: %s\n", strerror(errno));
return EXIT_FAILURE;
}
char sender_ip_str[20];
inet_ntop(AF_INET, &(sender.sin_addr), sender_ip_str, sizeof(sender_ip_str));
printf ("Received IP packet with ICMP content from: %s\n", sender_ip_str);
struct ip* ip_header = (struct ip*) buffer;
ssize_t ip_header_len = 4 * ip_header->ip_hl;
printf ("IP header: ");
print_as_bytes (buffer, ip_header_len);
printf("\n");
printf ("IP data: ");
print_as_bytes (buffer + ip_header_len, packet_len - ip_header_len);
printf("\n\n");
}
return EXIT_SUCCESS;
}
|
