Hi Xun,

On 10/22/2013 08:15 AM, Ni, Xun wrote:

Hello, Daniel:
can all your examples block early before doing network operations?

I was referring to Linux Security Module which allows
to define access policies for an application e.g. which ports are
allowed to be used.

If the goal is just to block those ports you don't have to go through
half of the networking stack to figure out via an iptable rules that
this access is not allowed.

What's the whole netfilter universe? Can you give us more clear
examples?

I am not sure if I understood your question correctly. In case you
are asking what netfilter is I would like pointing you to the
http://www.netfilter.org/ project page.

cheers,
daniel