Re: [Full-Disclosure] Blocking Music Sharing.

[Nick FitzGerald <nick@xxxxxxxxxxxxxxxxxxx>]

"Johnson, Mark" <mjohnson@xxxxxxxx> wrote:

> Due to the legal issues, I am trying to block access to sites like Kazaa
> and Limewire in the office.  If I am not mistaken, these networks can
> use different ports each time, so there is no way to block it at the
> firewall.  Is this right?  And if so, what is the best way to block
> access to these types of sites?

You seem to be making the mistake of asking a "how do we detect X is 
happening?" question when it sounds as if you really want the "how do 
we prevent X from happening?" solution.

As you seem to be aware, detection of such protocols is fairly 
problematic.  And, even though it is doable for some currently 
interesting sub-set of all protocols you may find problematic, it is 
unlikely that will always be the case.

A better solution is to approach it as a policy issue and have 
enforcement of "allowable" software on the client machines.  There are 
very few products to help with such solutions for now.  Conventionally
-- perhaps there is some natural bias in human thought processes that, 
in such situations, strongly tends to the  "wrong" approach being seen 
as the "obvious" or "natural" one?? -- the products that are available 
are designed to answer "how do we detect...?" style questions.

Anyway, products that can monitor (and preferably detect but prevent) 
the execution of non-sanctioned programs should then feed into an HR 
policy about the use of non-sanctioned software on your corporate PCs 
with suitable disincentives attached -- loss of bonuses or other 
performance payments, "black marks" in the promotion ladder, formal 
warnings, etc.


-- 
Nick FitzGerald
Computer Virus Consulting Ltd.
Ph/FAX: +64 3 3529854

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