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http://www.hackerschool.org/HS_Boards/zboard.php?AllArticle=true&no=8601 [º¹»ç]


ka0r1@ka0r1-GF63-Thin-11UC:~$ cat http_sniffer.c
void packet_handler(u_char *user_data, const struct pcap_pkthdr *pkthdr, const u_char *packet) {
    if (pkthdr->len < 14) {
        printf("Too short for Ethernet header\n");
        return;
    }

    struct ip *ip_header = (struct ip *)(packet + 14);
    int ip_header_len = ip_header->ip_hl * 4;

    if (pkthdr->len < 14 + ip_header_len) {
        printf("Too short for IP header\n");
        return;
    }

    struct tcphdr *tcp_header = (struct tcphdr *)(packet + 14 + ip_header_len);
    int tcp_header_len = tcp_header->th_off * 4;

    if (pkthdr->len < 14 + ip_header_len + tcp_header_len) {
        printf("Too short for TCP header\n");
        return;
    }

    const u_char *payload = packet + 14 + ip_header_len + tcp_header_len;
    int payload_len = pkthdr->len - (14 + ip_header_len + tcp_header_len);

    printf("Packet captured:\n");
    printf("From: %s\n", inet_ntoa(ip_header->ip_src));
    printf("To:   %s\n", inet_ntoa(ip_header->ip_dst));
    printf("Payload (%d bytes):\n", payload_len);

    if (payload_len > 0)
        print_hex_ascii(payload, payload_len);
    else
        printf("[No Payload]\n");

    printf("--------------------------------------------------\n");
}


=================================================================





$ sudo ./libpcap_capture
Packet catured:
Packet length: 85 bytes
01 00 5e 00 00 fb 50 b7 c3 9e d1 67 08 00 45 00   ..^...P....g..E.
00 47 de 62 00 00 01 11 5e 38 c0 a8 db 67 e0 00   .G.b....^8...g..
00 fb 14 e9 14 e9 00 33 af 2c 00 00 00 00 00 01   .......3.,......
00 00 00 00 00 00 0e 5f 6d 69 63 72 6f 73 6f 66   ......._microsof
74 5f 6d 63 63 04 5f 74 63 70 05 6c 6f 63 61 6c   t_mcc._tcp.local
00 00 0c 80 01                                    .....

Packet catured:
Packet length: 105 bytes
33 33 00 00 00 fb 50 b7 c3 9e d1 67 86 dd 60 0d   33....P....g..`.
e9 46 00 33 11 01 fe 80 00 00 00 00 00 00 f8 44   .F.3...........D
0b 56 13 a9 68 bb ff 02 00 00 00 00 00 00 00 00   .V..h...........
00 00 00 00 00 fb 14 e9 14 e9 00 33 ad ba 00 00   ...........3....
00 00 00 01 00 00 00 00 00 00 0e 5f 6d 69 63 72   ..........._micr
6f 73 6f 66 74 5f 6d 63 63 04 5f 74 63 70 05 6c   osoft_mcc._tcp.l
6f 63 61 6c 00 00 0c 80 01                        ocal.....

Packet catured:
Packet length: 86 bytes
80 ca 4b 86 e9 d5 84 7b 57 67 a5 0c 08 00 45 00   ..K....{Wg....E.
00 48 af b5 00 00 40 11 58 f0 c0 a8 db 2b 3d 29   .H....@.X....+=)
99 02 cb 13 00 35 00 34 72 45 82 f8 01 00 00 01   .....5.4rE......
00 00 00 00 00 00 01 31 03 32 31 39 03 31 36 38   .......1.219.168
03 31 39 32 07 69 6e 2d 61 64 64 72 04 61 72 70   .192.in-addr.arp
61 00 00 0c 00 01                                 a.....

Packet catured:
Packet length: 135 bytes
84 7b 57 67 a5 0c 80 ca 4b 86 e9 d5 08 00 45 00   .{Wg....K.....E.
00 79 59 61 00 00 37 11 b8 13 3d 29 99 02 c0 a8   .yYa..7...=)....
db 2b 00 35 cb 13 00 65 e9 86 82 f8 81 83 00 01   .+.5...e........
00 00 00 01 00 00 01 31 03 32 31 39 03 31 36 38   .......1.219.168
03 31 39 32 07 69 6e 2d 61 64 64 72 04 61 72 70   .192.in-addr.arp
61 00 00 0c 00 01 c0 12 00 06 00 01 00 00 03 2b   a..............+
00 25 09 6c 6f 63 61 6c 68 6f 73 74 00 04 72 6f   .%.localhost..ro
6f 74 00 00 00 00 01 00 09 3a 80 00 01 51 80 00   ot.......:...Q..
24 ea 00 00 09 3a 80                              $....:.

Packet catured:
Packet length: 85 bytes
01 00 5e 00 00 fb 50 b7 c3 9e d1 67 08 00 45 00   ..^...P....g..E.
00 47 de 63 00 00 01 11 5e 37 c0 a8 db 67 e0 00   .G.c....^7...g..
00 fb 14 e9 14 e9 00 33 af ac 00 00 00 00 00 01   .......3........
00 00 00 00 00 00 0e 5f 6d 69 63 72 6f 73 6f 66   ......._microsof
74 5f 6d 63 63 04 5f 74 63 70 05 6c 6f 63 61 6c   t_mcc._tcp.local
00 00 0c 00 01                                    .....

Packet catured:
Packet length: 105 bytes
33 33 00 00 00 fb 50 b7 c3 9e d1 67 86 dd 60 0d   33....P....g..`.
e9 46 00 33 11 01 fe 80 00 00 00 00 00 00 f8 44   .F.3...........D
0b 56 13 a9 68 bb ff 02 00 00 00 00 00 00 00 00   .V..h...........
00 00 00 00 00 fb 14 e9 14 e9 00 33 ae 3a 00 00   ...........3.:..
00 00 00 01 00 00 00 00 00 00 0e 5f 6d 69 63 72   ..........._micr
6f 73 6f 66 74 5f 6d 63 63 04 5f 74 63 70 05 6c   osoft_mcc._tcp.l
6f 63 61 6c 00 00 0c 00 01                        ocal.....

  Hit : 1316     Date : 2025/04/20 09:04