Firewall Wizards mailing list archives

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


From: Eric Vyncke <evyncke () cisco com>
Date: Fri, 22 Nov 2002 10:55:49 +0100

At 10:50 22/11/2002 +0100, Mikael Olsson wrote:

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.

Right, but my point was that those applications require at least one peer without firewall (= accepting incoming 
connection). So, blocking incoming connections will cut the bandwidth by at least 50% (as a lot of P2P users are behind 
NAT or firewalls)

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

Agreed, you then get what you want ;-)

-eric

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