리눅스 패킷캡쳐 하고있는데요..

지금 시간당 패킷 캡쳐할려고 하는데 너무 어렵네요.
시간당 캡쳐할려면

소스 중간에
pcap_open_live 부분만 바꿔주면은 되는건가요??ㅠㅠ

#include
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#include
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#include
#include
#include
#include
#include
#include
#include
#include
#include
#include

#define MAXBYTES2CAPTURE 2048

struct ip *iph;
struct tcphdr *tcph;

float threshold = 10.0;
float syn_rate =0.0;

time_t previous_time =0;
time_t current_time =0;

int num_sample =0;

void processPacket(u_char * useless, const struct pcap_pkthdr* pkthdr, const u_char* packet){

static int count = 1;
struct ether_header *ep;
unsigned short ether_type;
int chcnt =0;
int length = pkthdr->len;
int i;

ep = (struct ether_header *) packet;
packet += sizeof(struct ether_header);
ether_type = ntohs(ep->ether_type);

if(ether_type == ETHERTYPE_IP) {
iph = (struct ip *) packet;
printf("IP Packet\n");
printf("Version : %d\n", iph->ip_v);
printf("Header Len : %d\n", iph->ip_hl);
printf("Src Addr : %s\n", inet_ntoa(iph->ip_src));
printf("Dest Addr : %s\n", inet_ntoa(iph->ip_dst);

// pps 瑜?援ы븷?ㅻ㈃? if 臾??덉뿉???섏젙?대낫??. 留덉?留?ppt 蹂대㈃?€ ?⑦궥罹≪퀜瑜??좊븣 tcpdump ip (?꾪꽣?섎뒗寃? 'tcp[tcpflags] & (tcp-syn[tcp-fin)!=0 ~~~

if(iph->ip_p == IPPROTO_TCP) {
packet +=iph->ip_hl*4;
tcph = (struct tcp *) packet;

if(tcph->th_flags ==TH_SYN){

if(current_time == 0){
current_time = time();
num_syn=1;
rate = num_syn/60.0 //rate calculation
}

else if(current_time >0){ //泥섏쓬???쒕쾲 ?ㅽ뻾?덉쑝?덇퉸 else if
if (previous_time ==0 ) //?댁쟾?쒓컙 ?ㅼ젙???덈맟?쇰?濡?0
previous_time = current_time;
current_time =time();
if difftime(current_time,previous_time) <60)
rate =(num_syn + 1)/60.0; //rate 珥덈떦怨꾩궛

else if (difftime(current_time,previous_time) >=60)
printf("recent syn packet rate (/sec) is %f",rate);
num_sample++;
avg_rate = (avg_rate*num_sample-1)+rate)/num_sample;
printf("AVG syn packet rate (/sec) is %f",avg_rate);
previous_time = current_time;
num_syn =1;
rate = num_syn/60.0; //rate calculation

}

}
}

if(rate > threshold)
printf(" Alarm !!! the tcp syn scan is occurred~~ \n");

printf("Src Port : %d \n", ntohs(tcph->source));
printf("Dst Port : %d \n", ntohs(tcph->dest));
}

printf("Payload: \n");
for (i=0; ilen; i++) {
if(isprint(packet[i]))
printf("%c ", packet[i]);
else
printf(". ");

if( (i%16 == 0 && i != 0 ) || i == pkthdr->len-1 );
printf("\n");
}

return;
}

int main(int argc, char **argv){
int i=0, count=0;
pcap_t *descr = NULL;
char errbuf[PCAP_ERRBUF_SIZE], *device=NULL;
memset(errbuf, 0, PCAP_ERRBUF_SIZE);

char *net;
char *mask;
bpf_u_int32 netp;
bpf_u_int32 maskp;

struct in_addr addr;
struct bpf_program fp;

device = pcap_lookupdev(errbuf);

printf("Openinig device %s\n", device);
pcap_lookupnet(device,&netp, &maskp,errbuf);

addr.s_addr = netp;
net= inet_ntoa(addr);
printf("NET: %s\n",net);

addr.s_addr = maskp;
mask =inet_ntoa(addr);
printf("MASK: %s\n",mask);

getchar();

descr = pcap_open_live(device, MAXBYTES2CAPTURE, 1, 512, errbuf);

pcap_compile(descr,&fp, argv[2], 0, netp);

pcap_setfilter(descr, &fp);

pcap_loop(descr, atoi(argv[1]), processPacket, (u_char *) &count);

return 0;
}