Re: urgend file type detection

Steffen Heil wrote:

> I want to allow only mail through my sarge exim 4.34 heavy daemon server
> with clamav that have
> - NO attachments
> - ONLY rtf, doc, pdf, txt, xls attachments Everything else should be
> blocked.

Use the MIME ACL.

> However, I do not want to determine this by extension, but by content.
> rfc, doc, pdf als xls should be detectable, as they have special file
> structures. txt will propably more complicated.

Matching content-type headers is useless with MS software. You can apply 
clever mime_regex checks to determine the real file content. With .txt, 
check if the file does not contain binary zeroes. Not 100% secure but 
should catch most of possible fakes.

/tom