i> Hi again! I need help with libnetfilter_queue, I searched examples,
i> but I only found one simple test. My problem is that i need source ip
i> and source port, but i don't know how can i get from struct nfq_data
i> *pkt in the callback function.
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>
static int ob_netfilter_callback(struct nfq_q_handle *qh, struct nfgenmsg *nfmsg,
struct nfq_data *nfa, void *data)
{
............
u_int16_t ip_packet_len = 0;
struct ip *ip_packet = NULL;
struct tcphdr *tcp_packet = NULL;
char *payload;
..........
nfq_get_payload(nfa, &payload);
ip_packet = ((struct ip *)payload);
ip_packet_len = ntohs(ip_packet->ip_len);
printf("Source IP %s\n",inet_ntoa(ip_packet->ip_src));
if (ip_packet->ip_p == IPPROTO_TCP) {
tcp_packet = (struct tcphdr *)(payload + sizeof(struct ip));
if (ntohs(tcp_packet->dest) == 25) { // SMTP PORT
printf("this is SMTP");
};
};
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