import urllib
import os
import shutil

hostspath = "C:\\Windows\\System32\\drivers\\etc"
savepath = hostspath + "\\hostsave"

def download_hosts(url = "http://my-hosts-file.googlecode.com/svn/trunk/hosts"):
os.chdir(hostspath)
if os.getcwd() != hostspath:
print("Switch Dir to System32 Error,check permission!\npwd:"+os.getcwd())
exit()
try:
urllib.urlretrieve(url, "hostsave")
except:
print '\t Error when retrieveing hosts file from url: ', url

def backup_hosts():
shutil.copy("hosts","hosts.bak")

def replace_hosts():
shutil.copy("hostsave", "hosts")
print("Replace original hosts file finished, then flush dns...")
os.remove(savepath)  
 os.system("ipconfig /flushdns")

def main():
download_hosts()
backup_hosts()
replace_hosts()
if **name** == '**main**':
main()