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Hi,

I want to capture the packets from a particular port using RAW_SOCKETS so i wrote the following program but i am not getting any output .
Please help.


#include <arpa/inet.h>
#include <netinet/in.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>

#define BUFLEN 512
#define NPACK 10
#define PORT 9930

void diep(char *s)
{
    perror(s);
    exit(1);
}

int main(void)
{
    struct sockaddr_in si_me, si_other;
    int s, i, slen=sizeof(si_other);
    char buf[BUFLEN];

    if ((s=socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_ALL))==-1)
        diep("socket");

    memset((char *) &si_me, 0, sizeof(si_me));
    si_me.sin_family = PF_PACKET;
    si_me.sin_port = htons(PORT);
    si_me.sin_addr.s_addr = htonl(INADDR_ANY);
    if (bind(s, &si_me, sizeof(si_me))==-1)
        diep("bind");

    for (i=0; i<NPACK; i++) {
        if (recvfrom(s, buf, BUFLEN, 0, &si_other, &slen)==-1)
            diep("recvfrom()");
        printf("Received packet from %s:%d\nData: %s\n\n", 
                inet_ntoa(si_other.sin_addr), ntohs(si_other.sin_port), buf);
    }

    close(s);
    return 0;
}
Posted
Comments
Richard MacCutchan 2-Dec-13 6:06am    
Use your debugger to find out what is happening, and check that the other end is sending messages.
Robert Clove 2-Dec-13 6:25am    
ya other end is sending messages i saw it through tcpdump
Richard MacCutchan 2-Dec-13 6:31am    
Then I can only assume that there is something wrong with your receiever, so you need to work with your debugger to discover why.
JMH_FR 6-Dec-13 9:29am    
Did you tried with SOCK_RAW instead of SOCK_DGRAM ? And did you check you have CAP_NET_RAW capacity (if you are not running your prog as root ) ?

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