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PO
primarykey
Id
14023557
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
0
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CreationDate
2012-12-24T16:15:11.060
FavoriteCount
0
LastActivityDate
2012-12-24T16:43:31.883
LastEditDate
2012-12-24T16:43:31.883
LastEditorUserId
1280954
OwnerUserId
1280954
ParentId
14021347
PostTypeId
2
Score
0
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0
LastEditorDisplayName
text
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Local IP header structure is wrong... my suggestion is to include the IP header provided with your distro (are you using linux? don't you?). What i did is just include linux/ip.h, rename ipheader structure reference to iphdr, and rename the ip header fields according to the structure described in the latter file. I tried to sniff packets with tcpdump and it works now (i didn't try with wireshark but it must work too) Try this fixed code: <pre><code>// Must be run by root lol! Just datagram, no payload/data #include <unistd.h> #include <stdio.h> #include <string.h> #include <arpa/inet.h> #include <sys/socket.h> #include <netinet/udp.h> #include <linux/ip.h> // The packet length #define PCKT_LEN 35 // UDP header's structure struct udpheader { unsigned short int udph_srcport; unsigned short int udph_destport; unsigned short int udph_len; unsigned short int udph_chksum; }; // total udp header length: 8 bytes (=64 bits) // Function for checksum calculation. From the RFC, // the checksum algorithm is: // "The checksum field is the 16 bit one's complement of the one's // complement sum of all 16 bit words in the header. For purposes of // computing the checksum, the value of the checksum field is zero." unsigned short csum(unsigned short *buf, int nwords) { // unsigned long sum; for(sum=0; nwords>0; nwords--) sum += *buf++; sum = (sum >> 16) + (sum &0xffff); sum += (sum >> 16); return (unsigned short)(~sum); } // Source IP, source port, target IP, target port from the command line arguments int main(int argc, char *argv[]) { int sd; // No data/payload just datagram char buffer[PCKT_LEN]; // Our own headers' structures struct iphdr *ip = (struct iphdr *) buffer; struct udpheader *udp = (struct udpheader *) (buffer + sizeof(struct iphdr)); // Source and destination addresses: IP and port struct sockaddr_in sin, din; int one = 1; const int *val = &one; memset(buffer, 0, PCKT_LEN); if(argc != 5) { printf("- Invalid parameters!!!\n"); printf("- Usage %s <source hostname/IP> <source port> <target hostname/IP> <target port>\n", argv[0]); exit(-1); } // Create a raw socket with UDP protocol sd = socket(PF_INET, SOCK_RAW, IPPROTO_UDP); if(sd < 0) { perror("socket() error"); // If something wrong just exit exit(-1); } else printf("socket() - Using SOCK_RAW socket and UDP protocol is OK.\n"); // The source is redundant, may be used later if needed // The address family sin.sin_family = AF_INET; din.sin_family = AF_INET; // Port numbers sin.sin_port = htons(atoi(argv[2])); din.sin_port = htons(atoi(argv[4])); // IP addresses sin.sin_addr.s_addr = inet_addr(argv[1]); din.sin_addr.s_addr = inet_addr(argv[3]); // Fabricate the IP header or we can use the // standard header structures but assign our own values. ip->ihl = 5; ip->version = 4; ip->tos = 16; // Low delay ip->tot_len = sizeof(struct iphdr) + sizeof(struct udpheader); ip->id = htons(54321); ip->ttl = 64; // hops ip->protocol = 17; // UDP // Source IP address, can use spoofed address here!!! ip->saddr = inet_addr(argv[1]); // The destination IP address ip->daddr = inet_addr(argv[3]); // Fabricate the UDP header. Source port number, redundant udp->udph_srcport = htons(atoi(argv[2])); // Destination port number udp->udph_destport = htons(atoi(argv[4])); udp->udph_len = htons(sizeof(struct udpheader)); // Calculate the checksum for integrity ip->check = csum((unsigned short *)buffer, sizeof(struct iphdr) + sizeof(struct udpheader)); // Inform the kernel do not fill up the packet structure. we will build our own... if(setsockopt(sd, IPPROTO_IP, IP_HDRINCL, val, sizeof(one)) < 0) { perror("setsockopt() error"); exit(-1); } else printf("setsockopt() is OK.\n"); // Send loop, send for every 2 second for 100 count printf("Trying...\n"); printf("Using raw socket and UDP protocol\n"); printf("Using Source IP: %s port: %u, Target IP: %s port: %u.\n", argv[1], atoi(argv[2]), argv[3], atoi(argv[4])); int count; int i; for(count = 1; count <=20; count++) { if((i = sendto(sd, buffer, PCKT_LEN, 0, (struct sockaddr *)&sin, sizeof(sin))) < 0) // Verify { perror("sendto() error"); exit(-1); } else { printf("Count #%u - sendto() is OK. Data Length# %d\n", count,i); sleep(2); } } close(sd); return 0; } </code></pre>
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1. This table or related slice is empty.
PostParentId
1. POWireshark doesn't detect any packet sent. sendto return 0
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 PTQuestion
PostTypePostTypeId
1. PTAnswer
UserLastEditorUserId
1. USDavide Berra
UserOwnerUserId
1. USDavide Berra
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