tage,” he notes. As a result, numerous
YouTube and Twitter knockoffs exist
in some countries, including China,
and other countries block services
such as Skype in order to protect gov-ernment-run telephone services and
Breaching censors’ Walls
Increasingly, students, dissidents,
journalists, bloggers, human rights
advocates, and others are challenging
Internet censorship. In the digital age,
they’re fighting back with an arsenal of
tools such as proxy servers that circumvent filtering by masking the user and
altering the way data flows to a Web
server or by VPNs that tunnel through
to other less censorious countries.
It’s a cat-and-mouse game, to be
sure. As individuals begin downloading and using proxy servers, it’s common for government censors to detect
the activity and block downloads, as
well as the proxies. However, the same
applications frequently become available at alternative sites and through
peer-to-peer services. Moreover, new
proxy servers continually spring up.
But VPNs represent a different challenge, and most censoring countries
are hesitant to block them because
they’re essential for commerce and
used heavily by foreign business leaders and diplomats.
Some services, like Tor, a free program offered by the nonprofit Tor Project, circumvent censorship by routing
communications across a distributed
network of relays located around the
world. These VPN tunnels make it possible to access blocked pages and sites,
china, like many
blocks Web sites
sporadically and in
no systematic way.
such as Facebook or YouTube. They
also allow journalists and dissidents
to publish Web sites and other services
without revealing their location.
Another free VPN application, AnchorFree Hotspot Shield, enables users to view otherwise censored Web
sites by converting the http protocol
to an encrypted https protocol and
providing users with a virtual identity. “Although the product was originally intended to serve as a universal
privacy and security offering, a growing number of people are looking for
a way to bypass controls and access
information freely,” says AnchorFree
CEO David Gorodyansky.
Both Tor Project and AnchorFree’s
Web sites are blocked in China. Nev-
ertheless, Gorodyansky claims that
usage in China has doubled since the
Chinese government began blocking
the site last summer. Potential users
download Tor and AnchorFree Hot-
spot Shield by visiting mirror sites or
by sending the companies an email
message and receiving a message
with a Windows- or Mac-compatible
file. In addition, individuals share ap-
plications with USB flash drives and
through peer-to-peer services.
Deibert, R.J., Palfrey, J.G., Rohozinskiand, R.,
Zittrain, J. (Eds.)
Access Denied: The Practice and Policy
of Global Internet Filtering, MIT Press,
Cambridge, MA, 2008.
“The Connection has Been Reset,” The
Atlantic, March 2008.
Cashing in on Internet censorship, Cnn.
com, February 19, 2010, http://www.cnn.
Reporters Without Borders
Enemies of the Internet, Reporters Without
Borders, March 12, 2010, http://www.rsf.
Samuel Greengard is an author and journalist based in
West linn, oR.
© 2010 ACM 0001-0782/10/0700 $10.00
CMU Researchers Analyze Twitter Sentiments
a computer analysis of people’s
sentiments in a billion Twitter
messages during 2008 and 2009
yielded measures of consumer
confidence and presidential
job approval similar to those of
public opinion polls, according
to Carnegie Mellon University
The findings suggest that
analyzing the text in tweets could
be an inexpensive, rapid means
of gauging public opinion on
some subjects, says Noah smith,
assistant professor of language
technologies and machine
learning at Carnegie Mellon.
however, the tools for extracting
public opinion from the text of
social media are crude and social
media remain in their infancy,
smith says, so the extent to which
these methods could supplement
or replace traditional public
opinion polls is unknown.
sentiment measurements were
much more volatile day-to-day
than the polling data, but when
the researchers “smoothed”
the results by averaging them
over a period of days, the results
often correlated closely with
the polling data, says brendan
o’Connor, a graduate student
in Carnegie Mellon’s Language
Technologies institute and first
author of the study.