Notwendigkeit Hilfe in Bezug auf ein Paket-Capture-Programm

Question

Im Folgenden ist ein Programm, dass Captures Pakete TCP und druckt Header bezogenen Informationen in der Konsole für jedes Paket. Ich habe auch einen Timer, so dass nach allen 1000 Millisekunden das heißt 1 Sekunde, die Häufigkeit des Auftretens der verschiedenen Flaggen und unterschiedlicher Anzahl von Src IPs, Ack nos und Seq nos angetroffen werden, geschrieben in eine Datei enthalten. Ich arbeite in Fedora Core 5. Ich bin Begegnung folgende Probleme auf:

1.file Schreibteil funktioniert bei einigen Ausführungen, aber die meisten anderen Zeiten, in der gleichen Maschine, ist die Datei überhaupt nicht geschrieben.

2. Wenn ich dieses Programm in meinem Haus ausführen, etwa 30 Pakete pro Sekunde erfasst werden. Aber wenn ich das gleiche Programm in meinem Labor laufen, nur 1 Paket pro Sekunde erfasst. (Obwohl ich tun, um die gleiche Menge an Surfen in beiden Orten)

#define INTERVAL 1000        /* number of milliseconds to go off */

#include <pcap.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/time.h> // for setitimer
#include<unistd.h>    // for pause
#include <signal.h>     /* for signal */

/* default snap length (maximum bytes per packet to capture) */
#define SNAP_LEN 1518

/* ethernet headers are always exactly 14 bytes [1] */
#define SIZE_ETHERNET 14

/* Ethernet addresses are 6 bytes */
#define ETHER_ADDR_LEN  6

/* Ethernet header */
struct sniff_ethernet {
        u_char  ether_dhost[ETHER_ADDR_LEN];    /* destination host address */
        u_char  ether_shost[ETHER_ADDR_LEN];    /* source host address */
        u_short ether_type;                     /* IP? ARP? RARP? etc */
};

/* IP header */
struct sniff_ip {
        u_char  ip_vhl;                 /* version << 4 | header length >> 2 */
        u_char  ip_tos;                 /* type of service */
        u_short ip_len;                 /* total length */
        u_short ip_id;                  /* identification */
        u_short ip_off;                 /* fragment offset field */
        #define IP_RF 0x8000            /* reserved fragment flag */
        #define IP_DF 0x4000            /* dont fragment flag */
        #define IP_MF 0x2000            /* more fragments flag */
        #define IP_OFFMASK 0x1fff       /* mask for fragmenting bits */
        u_char  ip_ttl;                 /* time to live */
        u_char  ip_p;                   /* protocol */
        u_short ip_sum;                 /* checksum */
        struct  in_addr ip_src,ip_dst;  /* source and dest address */
};
#define IP_HL(ip)               (((ip)->ip_vhl) & 0x0f)
#define IP_V(ip)                (((ip)->ip_vhl) >> 4)

/* TCP header */
typedef u_int tcp_seq;

struct sniff_tcp {
        u_short th_sport;               /* source port */
        u_short th_dport;               /* destination port */
        tcp_seq th_seq;                 /* sequence number */
        tcp_seq th_ack;                 /* acknowledgement number */
        u_char  th_offx2;               /* data offset, rsvd */
#define TH_OFF(th)      (((th)->th_offx2 & 0xf0) >> 4)
        u_char  th_flags;
        #define TH_FIN  0x01
        #define TH_SYN  0x02
        #define TH_RST  0x04
        #define TH_PUSH 0x08
        #define TH_ACK  0x10
        #define TH_URG  0x20
        #define TH_ECE  0x40
        #define TH_CWR  0x80
        #define TH_FLAGS        (TH_FIN|TH_SYN|TH_RST|TH_ACK|TH_URG|TH_ECE|TH_CWR)
        u_short th_win;                 /* window */
        u_short th_sum;                 /* checksum */
        u_short th_urp;                 /* urgent pointer */
};

u_short sport[100];int spd=0;
u_int seq[100];int seqd=0;
u_short win[100];int wind=0;

FILE* urlfile;
int count = 1,flag=0,t=0; 
float sc=0,ac=0,fc=0,pc=0,uc=0,rc=0;

void
got_packet(u_char *args, const struct pcap_pkthdr *header, const u_char *packet);

void
print_payload(const u_char *payload, int len);

void
print_hex_ascii_line(const u_char *payload, int len, int offset);



void
print_app_usage(void);

void DoStuff(void);

void DoStuff(void) {
    t++;
  printf("Timer %d went off.########################################\n",t);
 // fprintf(urlfile,"\n hi hi");
  fprintf(urlfile,"\ntime %d 1:%f 2:%f 3:%f 4:%f 5:%f 6:%f 7:%f 8:%f 9:%f",t,sc/count,ac/count,fc/count,pc/count,uc/count,rc/count,(float)spd/count,(float)wind/count,(float)seqd/count);
  printf("\ntime %d 1:%f 2:%f 3:%f 4:%f 5:%f 6:%f 7:%f 8:%f 9:%f",t,sc/count,ac/count,fc/count,pc/count,uc/count,rc/count,(float)spd/count,(float)wind/count,(float)seqd/count);
  printf("\n a_count : %f , total_packets : %d , frequency : %f",ac,count,ac/count);
  printf("\n r_count : %f , total_packets : %d , frequency : %f",rc,count,rc/count);
  printf("\n p_count : %f , total_packets : %d , frequency : %f",pc,count,pc/count);
  printf("\n s_count : %f , total_packets : %d , frequency : %f",sc,count,sc/count);
  printf("\n u_count : %f , total_packets : %d , frequency : %f",uc,count,uc/count);
  printf("\n f_count : %f , total_packets : %d , frequency : %f",fc,count,fc/count);
  printf("\ncount of distinct seq nos : %d no/pcount : %f ",seqd,(float)seqd/count);
  printf("\ncount of distinct sports : %d no/pcount : %f ",spd,(float)spd/count);
  printf("\ncount of distinct win nos : %d no/pcount : %f\n\n ",wind,(float)wind/count);
  ac=rc=pc=fc=sc=uc=0;count=1;  
  spd=seqd=wind=0;
}


void
print_app_usage(void)
{

    printf("Usage: ./a.out [interface]\n");
    printf("\n");
    printf("Options:\n");
    printf("    interface    Listen on <interface> for packets.\n");
    printf("\n");

return;
}


/*
 * dissect/print packet
 */
void
got_packet(u_char *args, const struct pcap_pkthdr *header, const u_char *packet)
{

                      /* packet counter */
    int j;
    /* declare pointers to packet headers */
    const struct sniff_ethernet *ethernet;  /* The ethernet header [1] */
    const struct sniff_ip *ip;              /* The IP header */
    const struct sniff_tcp *tcp;            /* The TCP header */
    const char *payload;                    /* Packet payload */

    int size_ip;
    int size_tcp;
    int size_payload;

    printf("\nPacket number %d:\n", count);
    count++;

    /* define ethernet header */
    ethernet = (struct sniff_ethernet*)(packet);

    /* define/compute ip header offset */
    ip = (struct sniff_ip*)(packet + SIZE_ETHERNET);
    size_ip = IP_HL(ip)*4;
    if (size_ip < 20) {
        printf("   * Invalid IP header length: %u bytes\n", size_ip);
        return;
    }

    switch(ip->ip_p) {
        case IPPROTO_TCP:
            printf("   Protocol: TCP\n");
            break;
        case IPPROTO_UDP:
            printf("   Protocol: UDP\n");
            return;
        case IPPROTO_ICMP:
            printf("   Protocol: ICMP\n");
            return;
        case IPPROTO_IP:
            printf("   Protocol: IP\n");
            return;
        default:
            printf("   Protocol: unknown\n");
            return;
    }

    /* define/compute tcp header offset */
    tcp = (struct sniff_tcp*)(packet + SIZE_ETHERNET + size_ip);
    size_tcp = TH_OFF(tcp)*4;
    if (size_tcp < 20) {
        printf("   * Invalid TCP header length: %u bytes\n", size_tcp);
        return;
    }

    flag=0;
    for(j=0;j<spd;j++)
    {      
       if(sport[j]==ntohs(tcp->th_sport)) { flag=1; break; }
    }
    if(flag==0) sport[spd++]=ntohs(tcp->th_sport);

    flag=0;
    for(j=0;j<seqd;j++)
    {      
       if(seq[j]==ntohs(tcp->th_seq)) { flag=1; break; }
    }
    if(flag==0) seq[seqd++]=ntohs(tcp->th_seq);

    flag=0;
    for(j=0;j<wind;j++)
    {      
       if(win[j]==ntohs(tcp->th_win)) { flag=1; break; }
    }
    if(flag==0) win[wind++]=ntohs(tcp->th_win);

    printf("   Src port: %d\n", ntohs(tcp->th_sport));
    printf("   Window: %d\n", ntohs(tcp->th_win));
    printf("   Sequence no: %d\n", ntohs(tcp->th_seq));

    if (tcp->th_flags & TH_URG){
        printf("   Flag: TH_URG");uc++;
    }
    if (tcp->th_flags & TH_RST){
        printf("   Flag: TH_RST");rc++;
    }
    if (tcp->th_flags & TH_ACK){
        printf("   Flag: TH_ACK");ac++;
    }
    if (tcp->th_flags & TH_PUSH){
        printf("   Flag: TH_PUSH");pc++;
    }
    if (tcp->th_flags & TH_SYN){
        printf("   Flag: TH_SYN");sc++;
    }
    if (tcp->th_flags & TH_FIN){
        printf("   Flag: TH_FIN");fc++;
    }


    if (size_payload > 0) {
        printf("   Payload (%d bytes):\n", size_payload);

    }

return;
}

int main(int argc, char **argv)
{

    char *dev = NULL;           /* capture device name */
    char errbuf[PCAP_ERRBUF_SIZE];      /* error buffer */
    pcap_t *handle;             /* packet capture handle */
    char filter_exp[] = "tcp port 80";
    struct bpf_program fp;          /* compiled filter program (expression) */
    bpf_u_int32 mask;           /* subnet mask */
    bpf_u_int32 net;            /* ip */
    //int num_packets = 10;         /* number of packets to capture */

    /* check for capture device name on command-line */
    if (argc == 2) {
        dev = argv[1];
    }
    else if (argc > 2) {
        fprintf(stderr, "error: unrecognized command-line options\n\n");
        print_app_usage();
        exit(EXIT_FAILURE);
    }
    else {
        /* find a capture device if not specified on command-line */
        dev = pcap_lookupdev(errbuf);
        if (dev == NULL) {
            fprintf(stderr, "Couldn't find default device: %s\n",
                errbuf);
            exit(EXIT_FAILURE);
        }
    }

    /* get network number and mask associated with capture device */
    if (pcap_lookupnet(dev, &net, &mask, errbuf) == -1) {
        fprintf(stderr, "Couldn't get netmask for device %s: %s\n",
            dev, errbuf);
        net = 0;
        mask = 0;
    }

    /* print capture info */
    printf("Device: %s\n", dev);
    printf("Filter expression: %s\n", filter_exp);

    /* open capture device */
    handle = pcap_open_live(dev, SNAP_LEN, 1, 1000, errbuf);
    if (handle == NULL) {
        fprintf(stderr, "Couldn't open device %s: %s\n", dev, errbuf);
        exit(EXIT_FAILURE);
    }

    /* make sure we're capturing on an Ethernet device [2] */
    if (pcap_datalink(handle) != DLT_EN10MB) {
        fprintf(stderr, "%s is not an Ethernet\n", dev);
        exit(EXIT_FAILURE);
    }

    /* compile the filter expression */
    if (pcap_compile(handle, &fp, filter_exp, 0, net) == -1) {
        fprintf(stderr, "Couldn't parse filter %s: %s\n",
            filter_exp, pcap_geterr(handle));
        exit(EXIT_FAILURE);
    }

    /* apply the compiled filter */
    if (pcap_setfilter(handle, &fp) == -1) {
        fprintf(stderr, "Couldn't install filter %s: %s\n",
            filter_exp, pcap_geterr(handle));
        exit(EXIT_FAILURE);
    }

    urlfile=fopen("output.txt","w");
    if(urlfile==NULL) printf("Unable to create file.");

    // timer code

    struct itimerval it_val;  /* for setting itimer */

  /* Upon SIGALRM, call DoStuff().
   * Set interval timer.  We want frequency in ms, 
   * but the setitimer call needs seconds and useconds. */
  if (signal(SIGALRM, (void (*)(int)) DoStuff) == SIG_ERR) {
    perror("Unable to catch SIGALRM");
    exit(1);
  }
  it_val.it_value.tv_sec =     INTERVAL/1000;
  it_val.it_value.tv_usec =    (INTERVAL*1000) % 1000000;   
  it_val.it_interval = it_val.it_value;
  if (setitimer(ITIMER_REAL, &it_val, NULL) == -1) {
    perror("error calling setitimer()");
    exit(1);
  }

    /* now we can set our callback function */
    //pcap_loop(handle, num_packets, got_packet, NULL);
    pcap_loop(handle,-1, got_packet, NULL);// set num_packets to -1 to capture indefinitely.
    /* cleanup */
    pcap_freecode(&fp);
    pcap_close(handle);
    fclose(urlfile);
    printf("\nCapture complete.\n");

return 0;
}

Da dies ein Teil meines Projektes ist, bin ich jetzt an dieser Stelle steckt .. Kann jemand bitte vorschlagen darüber, was falsch gelaufen hat .. Vielen Dank im Voraus.

Answer 1

Haben Sie versucht, fflush()?

Answer 2

Ich konnte das Problem nicht [2], mit nur einer kleinen Änderung im Filterausdruck lösen: Habe ich es aus „TCP-Port 80“ auf „tcp“. Und jetzt dieses Programm arbeitet auch in meinem Labor, wie es bei mir zu Hause hat.

nach wie vor, das Problem nicht [1] ist noch ungelöst .. Und darüber hinaus die Datei schreiben zu halten ist nicht mit der Konsole in Tempo / i o .. Bis die Konsole zeigt Capture-Details für 120 Sekunden, die Datei hat nur etwa 90 Sekunden - gefüllt Daten in .. ich frage mich, ob dies ein generelles Problem mit Datei i / o ..