I have a Ubuntu machine and I want to send spoofed IP address (.212) to a Windows machine. I am using a spoofing program for this which uses raw sockets.

  • - My machine's IP (Ubuntu)
  • - Spoofed IP (It's actually my IPhone IP)
  • - Destination (My Windows tablet)

Now whenever I pass the parameters (spoofed IP address and destination) to the output of the program, I never see any packet from Spoofed IP to destination in Wireshark. All I see is a packet from an unknown IP source ( to the spoofed IP (.212). I am unable to figure out what is going on Linux.

Command usage: ./rawudp <source hostname/IP> <source port> <target hostname/IP> <target port>

My Command : ./a.out 80 8080

Here is the screenshot: http://tinypic.com/r/ofrfb5/8

Here is the program: http://pastebin.com/cT4TBsKU

The source code directly:

// ----rawudp.c------
// Must be run by root lol! Just datagram, no payload/data

#include <unistd.h>
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/ip.h>
#include <netinet/udp.h>
# include <string.h>
#include <stdlib.h>

// The packet length
#define PCKT_LEN 8192

// Can create separate header file (.h) for all headers' structure
// The IP header's structure
struct ipheader
    unsigned char iph_ihl:5, iph_ver:4;
    unsigned char iph_tos;
    unsigned short int iph_len;
    unsigned short int iph_ident;
    unsigned char iph_flag;
    unsigned short int iph_offset;
    unsigned char iph_ttl;
    unsigned char iph_protocol;
    unsigned short int iph_chksum;
    unsigned int iph_sourceip;
    unsigned int iph_destip;

// 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 ipheader *ip = (struct ipheader *) buffer;
    struct udpheader *udp = (struct udpheader *) (buffer + sizeof(struct ipheader));
    // 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]);

    // 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
    } 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->iph_ihl = 5;
    ip->iph_ver = 4;
    ip->iph_tos = 16; // Low delay
    ip->iph_len = sizeof(struct ipheader) + sizeof(struct udpheader);
    ip->iph_ident = htons(54321);
    ip->iph_ttl = 64; // hops
    ip->iph_protocol = 17; // UDP
    // Source IP address, can use spoofed address here!!!
    ip->iph_sourceip = inet_addr(argv[1]);
    // The destination IP address
    ip->iph_destip = 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->iph_chksum = csum((unsigned short *) buffer, sizeof(struct ipheader) + 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");
    } else
        printf("setsockopt() is OK.\n");

    // Send loop, send for every 2 second for 100 count
    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;
    for (count = 1; count <= 20; count++)
        // Verify
        if (sendto(sd, buffer, ip->iph_len, 0, (struct sockaddr *) &sin, sizeof(sin)) < 0)
            perror("sendto() error");
        } else
            printf("Count #%u - sendto() is OK.\n", count);
    return 0;

migrated from security.stackexchange.com Oct 6 '15 at 15:00

This question came from our site for information security professionals.

  • Can you link the source code into pastebin or similar, just to ensure we are looking the same code. Also, can you paste the command you used to run the program? – Zokol Oct 6 '15 at 6:40
  • Also, a dump of the network traffic (wireshark or tcpdump) would be helpful to see what is happening. – David Scholefield Oct 6 '15 at 6:41
  • 1
    Could you clarify your question by providing names (fictitious ones) to the 2 machines involved since their @IP can't be used as a way to understand which one you are talking of. On which machine are you running Wireshark? – daniel Azuelos Oct 6 '15 at 7:21
  • Just a guess but, try to run your program as root. Also, use wireshark locally on the sending machine and on the receiving machine. Stay safe ;) – BrunoMCBraga Oct 6 '15 at 12:47
  • Hey guys, thanks for responding. I have included more details in the original post – srkmish Oct 6 '15 at 23:33

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