I have an ftp to which my application will connect to make a software update. A text file on the ftp contains all SERIAL NUMBERS that are eligible to download the update.

The way I was going to do it: My application downloads the file and check the application's serial number against the downloaded list. I still think this would work ok, but just in case some kind of "hacker" (let's just not play on words) could do something against that - I wondered if a file can be checked on the ftp, without downloading it.

Afterall, it's only a textfile in which SN are written one after the other. If it comes local on a machine, even tho the process takes 1 second and the file is deleted afterward, I'm afraid someone could find a way to have unlimitted updates.

Thanks.