forcing FTP-uploaded files to be of certain types only

[Mikhail Teterin]

Hello!

We run an FTP server for the customers to upload their data (usually -- giant 
core-files and database-dumps).

Sometimes they forget compress them, however, wasting many gigabytes of our 
server's space...

How hard would it be to make the stock FreeBSD FTP-server to examine the 
first, say, 100Kb of the uploaded file and interrupt transfer if the file is 
of a prohibited or is not of an allowed type?

Anything under 100Kb is fine, I guess, and 100Kb is more than enough to detect 
compression or lack thereof...

Thanks for ideas!

	-mi