Re: Port numbers for Peer to Peer file sharing apps.

[Mikael Olsson <mikael.olsson () clavister com>]

Eric Vyncke wrote:
> If you are concerned only by the waste of bandwidth, you may want to:
> - block all incoming TCP connections but the really needed ones

Um. That doesn't work for kazaa (fasttrack), gnutella, etc.
These apps will detect if they're firewalled, and if two peers want
to talk to eachother where one side is firewalled, the connection 
will always be initiated by the firewalled one.

(And for public networks, every port is "needed" if you ask the users.)


> - instead of blocking port 1214, ... you may want to use QoS feature 
> on router or ... to limit the bandwidth to a few kbps
>
> The reason behind the second point is to fool the cluefull students: 
> some traffic is going anyway, so, they will not try other ports but 
> the default.

This would fool the clueLESS ones. It might hold the clueful ones at 
bay for a few weeks, until they realize "Hey, that's strange, I'm 
consistently getting N times the bandwidth when I leach 1337 stuff 
on IRC or via FTP.", at which point the worst bandwidth hogs _will_
move on to other protocols, or maybe start fiddling with their port 
number settings... and tell all their friends.

Read this:
http://helpdesk.gwu.edu/helpdesk/whatsnew/fall02/kazaa.100902.html
  "Kazaa v2 is bypassing all our controls! Argh!"

And then take into account "helpful" sites like this one I found 
right away when googling for "get around bandwidth limits kazaa":
http://www.dslreports.com/forum/remark,4481903~root=campus~mode=flat

 "Have you tried:
  Socks2Http - Tool to bypass firewalls and proxys that may be 
               blocking KaZaA.

  Socks2HTTP is an agent converting SOCKS v.5 requests into HTTP requests 
  and tunneling them through HTTP proxy. [...]"

(And now I'm making it even easier to find when this gets added to the
 web archives. *sigh*)

> NB: I admit that this is not an absolute design ;-)

You'd better :P


-- 
Mikael Olsson, Clavister AB
Storgatan 12, Box 393, SE-891 28 ÖRNSKÖLDSVIK, Sweden
Phone: +46 (0)660 29 92 00   Mobile: +46 (0)70 26 222 05
Fax: +46 (0)660 122 50       WWW: http://www.clavister.com
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