title: How can I tell if a file on an FTP is identical to a local file with out actually downloading the file?
body: <p>I'm writing a simple program that is used to synchronize files to an FTP. I want to be able to check if the local version of a file is different from the remote version, so I can tell if the file(s) need to be transfered. I could check the file size, but that's not 100% reliable because obviously it's possible for two files to be the same size but contain different data. The date/time the files were modified is also not reliable as the user's computer date could be set wrong.</p>
  
  <p>Is there some other way to tell if a local file and a file on an FTP are identical?</p>