Notices for planetlab: message number 00059
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FYI: [PlanetLab-PIs] open proxy complaints]

-------- Original Message --------
Subject: 	[SPAM: 6.280] [PlanetLab-PIs] open proxy complaints
Date: 	Mon, 12 Oct 2009 13:13:22 -0400
From: 	Larry Peterson <llp@cs.princeton.edu>
To: 	pis@lists.planet-lab.org, techs@lists.planet-lab.org

We periodically receive complaints about open proxies running
on PlanetLab. There seems to be a recent up-tick in this sort of
activity, probably because some new site has started to sell a list
of proxies, and they don't take the time to understand what nodes
are actually usable as open proxies. Nor do they have any incentive
to do so -- the more IP addresses on their list, the more "valuable"
their service.

It would be helpful for all PIs and Tech contacts to understand why
this happens. The following is the response typically sent by the
researchers running the CoDeen slice.



We receive many queries about whether CoDeeN is an open proxy, and
whether it is safe for the hosting institutions. CoDeeN uses
semi-restricted proxies, with a number of protections against the abuse
normally encountered by open proxies. Some of these are described below:

  * Sites that contained licensed content, such as electronic journals
and databases, are not accessible by the general public. In this manner,
an organization does not have to worry about protecting its
subscriptions from unauthorized access.

  * Requests are not forwarded from a client outside the organization
to a server within the organization via a local proxy. In this way,
pages with IP-address restrictions cannot be viewed by outsiders.

  * We test a number of known virus and attack signatures, and
automatically ban clients attempting to use these attacks.

  * We log all accesses, and cooperate with investigations of abuse.
All clients using CoDeeN are greeted with a splash screen providing
information on our privacy policies.

  * We restrict the HTTP methods we allow, as well as the ports that
can be accessed. As a result, clients cannot post content, upload files,
or access non-HTTP services, such as SMTP-based e-mail.

  * We detect robotically-generated traffic and place more restrictions
on it in terms of request behavior. Robots are banned quite
aggressively, as soon as we detect any suspicious-looking traffic.

  * Despite these steps, some Web sites still list CoDeeN among their
"anonymous" or "elite" proxies. The reason for this is because most of
these sites make money selling access to their lists or to their
proxy-hopping software. By advertising larger lists, their service looks
more impressive than it really is. Many of the more honest sites have
begun to either separate out CoDeeN proxies or offer tools to avoid
using them.

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