Wireshark-dev: [Wireshark-dev] request help for packet capture using libpcap
Date: Tue, 6 May 2008 16:40:25 +0530
Hello ,
I have been trying to write a small application using libpcap library.
Purpose is to capture some live network packets(say 100 packets) and store them in a file (pcap_savefile).
Please refer the attachment for the code.
As per my understanding the pcap_savefile should be in "pcap" format as this is the default file format for libpacp.
But when I pass this file to wireshark, it does not show any packet data.
Also the size of the pcap_savefile is just around 24 bytes for 100 packets.
So I was wondering whether the programm is actually capturing any network packet.
Could anyone please suggest how I can improve the programe and store the data in pcap format.
Thanks in advance.

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#include <unistd.h>
#include <stdio.h>
#include <pcap.h>
#include <netinet/in.h>
#include <sys/socket.h>

#define IFSZ 16
#define FLTRSZ 120
#define MAXHOSTSZ 256
#define PCAP_SAVEFILE "./pcap_savefile"

void my_callback(u_char *args, const struct pcap_pkthdr * pkthdr, const u_char* packet){
printf("Welcome ... \n");

int main(){

pcap_t *p;               /* packet capture descriptor */
pcap_dumper_t *pd;       /* pointer to the dump file */
char filename[80];       /* name of savefile for dumping packet data */
int count = 20;          /* number of packets to capture */
pcap_if_t *alldevs;
char *err_str, *err_buf;
int n=0;
char * ifname1;


ifname1 = pcap_lookupdev(err_buf);
p =  pcap_open_live(ifname1, 65545, 0, 1000, err_buf);
pd = pcap_dump_open(p,filename);

pcap_loop(p,100,my_callback,(char *)pd);


return 0;