[Winpcap-users] it doesn't show the correct ports

Ziara . essence_z at hotmail.com
Thu Mar 20 10:42:05 GMT 2008

Ok, I found my mistake, I don't know why but I'm thinking that udp packets had 80 port too, I check my tcp ports and they are correct, sorry for bothering you.
And one question, could it be to have the same port, source and destination for a udp packets? 

From: essence_z at hotmail.comTo: winpcap-users at winpcap.orgDate: Wed, 19 Mar 2008 13:56:10 +0100Subject: [Winpcap-users] it doesn't show the correct ports

Hello, I can't explain why in this code when I output source and destination udp port, it show me port: 1042 and 53, it should be 80 instead of 53. and no always show the same port 1042. Porgramming in builder c++ ..int cont = 0;int res = pcap_next_ex(adhandle_, &header, &pkt_data);                if (res == 0)  //Timeout elapsed                    continue;                cont++;                cadenaIDx = AnsiString (cont);  //show the index                //Tiempo                local_tv_sec = header->ts.tv_sec;                ltime = localtime(&local_tv_sec);                strftime(timestr, sizeof timestr, "%H:%M:%S", ltime);                cadenaTIm = AnsiString(timestr) + "." + header->ts.tv_usec;  //show the time                ether_header *ether;                ether = (ether_header*)(pkt_data);                switch(htons(ether->h_type))                {                 case 0x0800: //IPv4                                ip_header *ip;                                udp_header *udp;                                u_int ip_len;                                ip = (ip_header*)(pkt_data + 14);                                sprintf(macaddr1,"%d.%d.%d.%d",ip->saddr.byte1,                                ip->saddr.byte2,ip->saddr.byte3,ip->saddr.byte4);                                sprintf(macaddr2,"%d.%d.%d.%d",ip->daddr.byte1,                                ip->daddr.byte2,ip>daddr.byte3,ip>daddr.byte4);                                             cadenaIPs = macaddr1; //show IP source address                                cadenaIPd = macaddr2; //show IP dest address                                 switch (ip->proto)                                {                                 case 1:                                        cadenaPRt = "ICMP";                                        break;                                 case 2:                                        cadenaPRt = "IGMP";                                        break;                                 case 4:                                        cadenaPRt = "IP";                                        break;                                 case 6:                                        cadenaPRt = "TCP";                                         break;                                 case 17:                                        cadenaPRt = "UDP";  //show protocol                                        ip_len = (ip->ver_ihl & 0xf) * 4; //Longitud de Ip header                                        udp = (udp_header*)((u_char*)ip + ip_len);                                        //udp = (udp_header*)(pkt_data+14+sizeof(ip_header));                                        cadenaSPo = ntohs(udp->sport);  //show udp source port                                        cadenaDPo = ntohs(udp->dport);  //show udp destination port                                        break;                                 default:                                        cadenaPRt = "?";                                        break;                              }                              break;                 case 0x0806:                        cadenaPRt = "ARP";                        arp_header *arp;                        arp = (arp_header*)(pkt_data + 14);                        sprintf(macaddr1,"%02X-%02X-%02X-%02X-%02X-%02X",arp->src_addr[0],                        arp->src_addr[1],arp->src_addr[2],arp->src_addr[3],arp->src_addr[4],                        arp->src_addr[5]);                        sprintf(macaddr2,"%02X-%02X-%02X-%02X-%02X-%02X",arp->dst_addr[0],                        arp->dst_addr[1],arp->dst_addr[2],arp->dst_addr[3],arp->dst_addr[4],                        arp->dst_addr[5]);                        cadenaIPs = macaddr1;                        cadenaIPd = macaddr2;                        break;                 default:                        cadenaPRt = "otros";                        break;                 } the struct header that I use: /* Cabecera ARP */struct arp_header{ u_short hardware; u_short protocol; u_char hw_addr_len; u_char proto_addr_len; u_short operation; u_char src_addr[6]; u_char src_ip[4]; u_char dst_addr[6]; u_char dst_ip[4];};//4 bytes IP addressstruct ip_address{ u_char byte1; u_char byte2; u_char byte3; u_char byte4;};// 20 bytes IP Headerstruct ip_header{ u_char ver_ihl; u_char tos; // Type of service u_short tlen; // Total length u_short identification; // Identification u_short flags_fo; // Flags (3 bits) + Fragment offset (13 bits) u_char ttl; // Time to live u_char proto; // Protocol u_short crc; // Header checksum ip_address saddr; // Source address ip_address daddr; // Destination address // u_int op_pad; // Option + Padding -- NOT NEEDED!}; struct udp_header{ u_short sport;          // Source port u_short dport;          // Destination port u_short len;            // Datagram length u_short crc;            // Checksum};

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