4J

Based on my earlier entry, I got the C sample code working. Hopefully you will know what to do from the remarks in the code:

/*
 * This code is GPL.
 */

/*
 *      Compiling: $ gcc -I/usr/include/libnetfilter_queue -L/usr/lib/libnetfilter_queue_libipq.so -o libipq_test_01 libipq_test_01.c -lipq
 *
 *      You will require the following iptables rules BEFORE running this program:
 *
 *              iptables -F
 *              iptables -A INPUT -j QUEUE
 *              iptables -A OUTPUT -j QUEUE
 *              iptables -A INPUT -j ACCEPT
 *              iptables -A OUTPUT -j ACCEPT
 *
 */

#include 
#include 
#include 

#define BUFSIZE 2048

static void die(struct ipq_handle *h)
{
        ipq_perror("passer");
        ipq_destroy_handle(h);
        exit(1);
}

int main(int argc, char **argv)
{
        int status;
        unsigned char buf[BUFSIZE];
        struct ipq_handle *h;

        h = ipq_create_handle(0, PF_INET);
        if (!h)
                die(h);

        status = ipq_set_mode(h, IPQ_COPY_PACKET, BUFSIZE);
        if (status < 0)
                die(h);

        fprintf( stderr, "Starting...\n" );
        do{
                status = ipq_read(h, buf, BUFSIZE, 0);
                if (status < 0)
                        die(h);

                switch (ipq_message_type(buf)) {
                        case NLMSG_ERROR:
                                fprintf(stderr, "Received error message %d\n",
                                        ipq_get_msgerr(buf));
                                break;

                        case IPQM_PACKET: {
                                fprintf( stderr, "Processed packet\n" );
                                ipq_packet_msg_t *m = ipq_get_packet(buf);

                                status = ipq_set_verdict(h, m->packet_id,
                                                         NF_ACCEPT, 0, NULL);
                                if (status < 0)
                                        die(h);

                                break;
                        }

                        default:
                                fprintf(stderr, "Unknown message type!\n");
                                break;
                }
        } while (1);

        ipq_destroy_handle(h);
        return 0;
}