Re: how to block files with specific extensions

[Martin Stricker <shugal@gmx.de>]

Stewart Thompson wrote:
> 
> Hi Saravanian:
> 
>         Netfilter is a packet based system. So, it don't think
> you can do what your proposing with it. There may be other
> applications that could that operate at a higher level in the
> OSI stack. If you give the list a better description of  your
> exact requirements. Someone might be able to make a
> suggestions.

Depending on what kind of files you want to filter, you will have to do
it in different software: To prevent downloading certain files with the
web browser or via FTP (which most browsers can do also), you need to
set up a web cache/proxy. Popular software for that on Linux is squid.
Then configure squid to deny the file extensions you don't like, and
configure netfilter to only accept HTTP/FTP connections from your proxy.

If you want to deny certain file types as e-mail attachments you have to
do so in your e-mail server software. Procmail should be able to, and
several ant-virus software can do this also.

Best regards,
Martin Stricker
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