Muchas gracias!
Eso es precisamente lo que necesitaba.
Bueno por ahora tengo este codigo....y ando un poco atascado.
No se como especificar mi ip de origen, y tampoco se porque me manda los FLAGS: FYN SYN PSH y NS, cuando en realidad solo deberia mandar el SYN....
#include <sys/types.h>
#define __FAVOR_BSD
#include <sys/socket.h>
#include <stdio.h>
#include <netdb.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>
#include <arpa/inet.h>
#include <string.h>
char data[1024] = "";
unsigned short csum(unsigned short *buf,int nwords)
{
//this function returns the checksum of a buffer
unsigned long sum;
for (sum = 0; nwords > 0; nwords--){sum += *buf++;}
sum = (sum >> 16) + (sum & 0xffff);
sum += (sum >> 16);
return (unsigned short) (~sum);
}
int createRaw(int protocol_to_sniff)
{
int raw_fd = socket(AF_INET, SOCK_RAW, protocol_to_sniff);
if (raw_fd < 0)
{
printf("ERROR creating raw socket\n"); return(1);
}else{
printf( "Raw Socket Created! :-D\n"); return raw_fd;
}
}
int bindRaw
(int socketToBind
,struct sockaddr_in
*sin) {
int err
= bind
(socketToBind
,(struct sockaddr
*)sin,sizeof(*sin)); if (err < 0)
{
printf("ERROR binding socket.\n"); return(1);
}else{
printf("Bound socket! :-D\n"); return 0;
}
}
int main(int argc,char* argv[])
{
//create raw socket for binding
int bindSocket = createRaw(6);
//create structures
unsigned char packetBuf[4096];
//specify port to bind to
bzero
((char *)&sin
,sizeof(sin)); sin.
sin_port = htons
(55000);
//bind socket
bindRaw(bindSocket,&sin);
//inform os of recieving raw ip packet
{
int tmp = 1;
setsockopt(bindSocket, 0, IP_HDRINCL,&tmp,sizeof(tmp));
}
//re-use socket structure
//Details about where this custom packet is going:
bzero
((char *)& sin, sizeof(sin)); sin.
sin_family = AF_INET
; sin.
sin_port = htons
(55000); //port to send packet to sin.
sin_addr.
s_addr = inet_addr
("173.194.34.215"); //IP to send packet to
unsigned short buffer_size = sizeof(struct ip) + sizeof(struct tcphdr);//+ sizeof(data);
//cout << "Buffer size: " << buffer_size << endl;
struct ip *IPheader = (struct ip *) packetBuf;
struct tcphdr *TCPheader = (struct tcphdr *) (packetBuf + sizeof (struct ip));
//Fill out IP Header information:
IPheader->ip_hl = 5;
IPheader->ip_v = 4; //IPv4
IPheader->ip_tos = 0; //type of service
IPheader->ip_len = htons(buffer_size); //length
IPheader->ip_id = htonl(54321);
IPheader->ip_off = 0;
IPheader->ip_ttl = 255; //max routers to pass through
IPheader->ip_p = 6; //tcp
IPheader->ip_sum = 0; //Set to 0 before calulating later
IPheader->ip_src.s_addr = inet_addr("11.11.11.11"); //source IP address
IPheader->ip_dst.s_addr = inet_addr("173.194.34.215"); //destination IP address
//Fill out TCP Header information:
TCPheader->th_sport = htons(55000); //source port
TCPheader->th_dport = htons(55000); //destination port
TCPheader->th_seq = 0;
TCPheader->th_ack = 0; //Only 0 on initial SYN
TCPheader->th_off = 0;
TCPheader->th_flags = TH_SYN; //SYN flag set
TCPheader->th_win = htonl(65535); //used for segmentation
TCPheader->th_sum = 0; //Kernel fill this out
TCPheader->th_urp = 0;
//Now fill out the checksum for the IPheader
IPheader->ip_sum = csum((unsigned short *) packetBuf, IPheader->ip_len >> 1);
//cout << "IP Checksum: " << IPheader->ip_sum << endl;
//create raw socket for sending ip packet
int sendRaw = createRaw(6);
if (sendRaw < 0)
{
printf( "ERROR creating raw socket for sending.\n"); return(1);
}else{
printf( "Raw socket created for sending! :-D\n"); }
int sendErr = sendto(sendRaw,packetBuf,
sizeof(packetBuf
),0,(struct sockaddr
*)&sin
,sizeof(sin));
if (sendErr < sizeof(packetBuf))
{
//cout << sendErr << " out of " << sizeof(packetBuf) << " were sent.\n";
return(1);
}else{
//cout << "<" << sendErr << "> Sent message!!! :-D\n";
}
printf( "Sleeping for 2 seconds"); sleep(1);
sleep(1);
char recvPacket[4096] = "";
int newData = recv(bindSocket,recvPacket,sizeof(recvPacket),0);
if (newData <=0)
{
//cout << newData << " returned by recv! :(\n";
return(1);
}else{
//cout << "<" << newData << "> RECIEVE SUCCESSFULL!! :-D\n";
}
return 0;
}
¿alguna idea?
Gracias.
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