<s>
UltraSurf	B-Application
is	O
a	O
freeware	B-License
Internet	B-Application
censorship	I-Application
circumvention	I-Application
product	O
created	O
by	O
UltraReach	B-Application
Internet	O
Corporation	O
.	O
</s>
<s>
The	O
software	O
bypasses	O
Internet	B-Application
censorship	I-Application
and	O
firewalls	B-Application
using	O
an	O
HTTP	O
proxy	B-Application
server	I-Application
,	O
and	O
employs	O
encryption	O
protocols	O
for	O
privacy	O
.	O
</s>
<s>
The	O
software	O
was	O
designed	O
as	O
a	O
means	O
of	O
allowing	O
internet	O
users	O
to	O
bypass	O
the	O
Great	O
Firewall	B-Application
of	O
China	O
.	O
</s>
<s>
Critics	O
in	O
the	O
open-source	B-Application
community	O
,	O
George	O
Turner	O
Says	O
,	O
have	O
expressed	O
concern	O
about	O
the	O
software	O
's	O
closed-source	B-Application
nature	O
and	O
alleged	O
security	O
through	O
obscurity	O
design	O
;	O
UltraReach	B-Application
says	O
their	O
security	O
considerations	O
mean	O
they	O
prefer	O
third	O
party	O
expert	O
review	O
to	O
open	O
source	O
review	O
.	O
</s>
<s>
In	O
2001	O
,	O
UltraReach	B-Application
was	O
founded	O
by	O
Chinese	O
dissidents	O
in	O
Silicon	O
Valley	O
.	O
</s>
<s>
Shortly	O
after	O
,	O
UltraSurf	B-Application
was	O
created	O
to	O
allow	O
internet	O
users	O
in	O
China	O
to	O
evade	O
government	O
censorship	O
and	O
monitoring	O
.	O
</s>
<s>
As	O
of	O
2011	O
UltraSurf	B-Application
reported	O
over	O
eleven	O
million	O
users	O
worldwide	O
.	O
</s>
<s>
During	O
the	O
Arab	O
Spring	O
,	O
UltraReach	B-Application
recorded	O
a	O
700	O
percent	O
spike	O
in	O
traffic	O
from	O
Tunisia	O
.	O
</s>
<s>
Wired	O
magazine	O
in	O
2010	O
called	O
UltraSurf	B-Application
"	O
one	O
of	O
the	O
most	O
important	O
free-speech	O
tools	O
on	O
the	O
Internet	O
"	O
for	O
enabling	O
citizens	O
to	O
access	O
and	O
share	O
information	O
from	O
oppressed	O
countries	O
during	O
times	O
of	O
humanitarian	O
or	O
human	O
rights	O
crises	O
.	O
</s>
<s>
UltraSurf	B-Application
is	O
funded	O
,	O
in	O
part	O
,	O
through	O
contracts	O
with	O
the	O
U.S.	O
government	O
's	O
Broadcasting	O
Board	O
of	O
Governors	O
,	O
which	O
administers	O
Voice	O
of	O
America	O
and	O
Radio	O
Free	O
Asia	O
.	O
</s>
<s>
As	O
of	O
2012	O
,	O
UltraReach	B-Application
has	O
had	O
difficulty	O
serving	O
its	O
growing	O
user	O
base	O
due	O
to	O
insufficient	O
funding	O
.	O
</s>
<s>
UltraSurf	B-Application
is	O
free	O
to	O
download	O
and	O
requires	O
no	O
installation	O
.	O
</s>
<s>
UltraSurf	B-Application
does	O
not	O
install	O
any	O
files	O
on	O
the	O
user	O
's	O
computer	O
and	O
leaves	O
no	O
registry	O
edits	O
after	O
it	O
exits	O
.	O
</s>
<s>
The	O
UltraReach	B-Application
website	O
notes	O
that	O
"	O
Some	O
anti-virus	O
software	O
companies	O
misclassify	O
UltraSurf	B-Application
as	O
a	O
malware	O
or	O
Trojan	O
because	O
UltraSurf	B-Application
encrypts	O
the	O
communications	O
and	O
circumvents	O
internet	O
censorship.	O
"	O
</s>
<s>
Some	O
security	O
companies	O
have	O
agreed	O
to	O
whitelist	O
UltraSurf	B-Application
.	O
</s>
<s>
According	O
to	O
Appelbaum	O
,	O
the	O
UltraSurf	B-Application
client	O
uses	O
anti-debugging	O
techniques	O
and	O
also	O
employs	O
executable	B-Application
compression	I-Application
.	O
</s>
<s>
The	O
client	O
acts	O
as	O
a	O
local	O
proxy	O
which	O
communicates	O
with	O
the	O
UltraReach	B-Application
network	O
through	O
what	O
appears	O
to	O
be	O
an	O
obfuscated	O
form	O
of	O
TLS/SSL	B-Protocol
.	O
</s>
<s>
The	O
software	O
works	O
by	O
creating	O
an	O
encrypted	O
HTTP	O
tunnel	O
between	O
the	O
user	O
's	O
computer	O
and	O
a	O
central	O
pool	O
of	O
proxy	B-Protocol
servers	I-Protocol
,	O
enabling	O
users	O
to	O
bypass	O
firewalls	B-Application
and	O
censorship	O
.	O
</s>
<s>
UltraReach	B-Application
hosts	O
all	O
of	O
its	O
own	O
servers	O
.	O
</s>
<s>
The	O
software	O
makes	O
use	O
of	O
sophisticated	O
,	O
proprietary	B-Application
anti-blocking	O
technology	O
to	O
overcome	O
filtering	O
and	O
censorship	O
online	O
.	O
</s>
<s>
According	O
to	O
Wired	O
magazine	O
,	O
UltraSurf	B-Application
changes	O
the	O
"	O
IP	O
addresses	O
of	O
their	O
proxy	B-Protocol
servers	I-Protocol
up	O
to	O
10,000	O
times	O
an	O
hour.	O
"	O
</s>
<s>
On	O
the	O
server-side	O
,	O
a	O
2011	O
analysis	O
found	O
that	O
the	O
UltraReach	B-Application
network	O
employed	O
squid	B-Protocol
and	O
ziproxy	B-Protocol
software	O
,	O
as	O
well	O
as	O
ISC	B-Protocol
BIND	I-Protocol
servers	O
bootstrapping	O
for	O
a	O
wider	O
network	O
of	O
open	O
recursive	O
DNS	O
servers	O
,	O
the	O
latter	O
not	O
under	O
UltraReach	B-Application
control	O
.	O
</s>
<s>
UltraSurf	B-Application
is	O
designed	O
primarily	O
as	O
an	O
anti-censorship	O
tool	O
but	O
also	O
offers	O
privacy	O
protections	O
in	O
the	O
form	O
of	O
industry	O
standard	O
encryption	O
,	O
with	O
an	O
added	O
layer	O
of	O
obfuscation	O
built	O
in	O
.	O
</s>
<s>
UltraReach	B-Application
uses	O
an	O
internal	O
content	O
filter	O
which	O
blocks	O
some	O
sites	O
,	O
such	O
as	O
those	O
deemed	O
pornographic	O
or	O
otherwise	O
offensive	O
.	O
</s>
<s>
Additionally	O
,	O
the	O
Falun	O
Gong	O
criticism	O
website	O
facts.org.cn,	O
alleged	O
to	O
be	O
operated	O
by	O
the	O
Chinese	O
government	O
,	O
is	O
also	O
unreachable	O
through	O
UltraSurf	B-Application
.	O
</s>
<s>
In	O
a	O
2007	O
study	O
,	O
Harvard	O
University	O
's	O
Berkman	O
Center	O
for	O
Internet	O
&	O
Society	O
found	O
UltraSurf	B-Application
to	O
be	O
the	O
"	O
best	O
performing	O
"	O
of	O
all	O
tested	O
circumvention	O
tools	O
during	O
in-country	O
tests	O
,	O
and	O
recommended	O
it	O
for	O
widespread	O
use	O
.	O
</s>
<s>
In	O
particular	O
,	O
the	O
report	O
found	O
that	O
UltraSurf	B-Application
effectively	O
bypassed	O
various	O
forms	O
of	O
censorship	O
and	O
blocking	O
,	O
include	O
IP	O
block	O
,	O
DNS	O
block	O
,	O
and	O
keyword	O
filtering	O
.	O
</s>
<s>
The	O
report	O
noted	O
,	O
however	O
,	O
that	O
UltraReach	B-Application
is	O
designed	O
primarily	O
as	O
a	O
circumvention	O
product	O
,	O
rather	O
than	O
as	O
an	O
anonymity	O
tool	O
,	O
and	O
suggested	O
that	O
users	O
concerned	O
about	O
anonymity	O
should	O
disable	O
browser	O
support	O
for	O
active	O
content	O
when	O
using	O
UltraSurf	B-Application
.	O
</s>
<s>
A	O
2011	O
report	O
by	O
the	O
U.S.-based	O
human	O
rights	O
group	O
Freedom	O
House	O
ranked	O
UltraSurf	B-Application
fourth	O
overall	O
among	O
censorship	B-Application
circumvention	I-Application
and	O
privacy	O
tools	O
,	O
as	O
measured	O
by	O
a	O
combination	O
of	O
performance	O
,	O
usability	O
,	O
support	O
and	O
security	O
.	O
</s>
<s>
Some	O
technologists	O
have	O
expressed	O
reservations	O
about	O
the	O
UltraReach	B-Application
model	O
,	O
however	O
.	O
</s>
<s>
In	O
particular	O
,	O
its	O
developers	O
have	O
been	O
criticized	O
by	O
proponents	O
of	O
open-source	B-Application
software	I-Application
for	O
not	O
allowing	O
peer	O
review	O
of	O
the	O
tool	O
's	O
design	O
,	O
except	O
at	O
the	O
discretion	O
of	O
its	O
creators	O
.	O
</s>
<s>
Moreover	O
,	O
because	O
UltraReach	B-Application
operates	O
all	O
its	O
own	O
servers	O
,	O
their	O
developers	O
have	O
access	O
to	O
user	O
logs	O
.	O
</s>
<s>
This	O
architecture	O
means	O
that	O
users	O
are	O
required	O
to	O
trust	O
UltraReach	B-Application
not	O
to	O
reveal	O
user	O
data	O
.	O
</s>
<s>
UltraReach	B-Application
maintains	O
that	O
it	O
keeps	O
logs	O
for	O
a	O
short	O
period	O
of	O
time	O
,	O
and	O
uses	O
them	O
only	O
for	O
the	O
purpose	O
of	O
analyzing	O
traffic	O
for	O
signs	O
of	O
interference	O
or	O
to	O
monitor	O
overall	O
performance	O
and	O
efficacy	O
;	O
the	O
company	O
says	O
it	O
does	O
not	O
disclose	O
user	O
logs	O
to	O
third	O
parties	O
.	O
</s>
<s>
According	O
to	O
Jacob	O
Appelbaum	O
with	O
the	O
Tor	B-Application
Project	I-Application
,	O
this	O
essentially	O
amounts	O
to	O
an	O
example	O
of	O
"	O
privacy	O
by	O
policy	O
"	O
.	O
</s>
<s>
In	O
an	O
April	O
2012	O
report	O
,	O
Appelbaum	O
further	O
criticized	O
UltraSurf	B-Application
for	O
its	O
use	O
of	O
internal	O
content	O
filtering	O
(	O
including	O
blocking	O
pornographic	O
websites	O
)	O
,	O
and	O
for	O
its	O
willingness	O
to	O
comply	O
with	O
subpoenas	O
from	O
U.S.	O
law	O
enforcement	O
officials	O
.	O
</s>
<s>
Appelbaum	O
's	O
report	O
also	O
noted	O
that	O
UltraSurf	B-Application
pages	O
employed	O
Google	B-Application
Analytics	I-Application
,	O
which	O
had	O
the	O
potential	O
to	O
leak	O
user	O
data	O
,	O
and	O
that	O
its	O
systems	O
were	O
not	O
all	O
up	O
to	O
date	O
with	O
the	O
latest	O
security	O
patches	O
and	O
did	O
not	O
make	O
use	O
of	O
forward	O
security	O
mechanisms	O
.	O
</s>
<s>
Furthermore	O
,	O
Appelbaum	O
claims	O
that	O
"	O
The	O
UltraSurf	B-Application
client	O
uses	O
Open	O
and	O
Free	O
Software	O
including	O
Putty	B-Operating_System
and	O
zlib	B-Language
.	O
</s>
<s>
The	O
use	O
of	O
both	O
Putty	B-Operating_System
and	O
zlib	B-Language
is	O
not	O
disclosed	O
.	O
</s>
<s>
In	O
a	O
response	O
posted	O
the	O
same	O
day	O
,	O
UltraReach	B-Application
wrote	O
that	O
it	O
had	O
already	O
resolved	O
these	O
issues	O
.	O
</s>
<s>
UltraReach	B-Application
also	O
argued	O
that	O
the	O
differences	O
between	O
the	O
software	O
approaches	O
to	O
Internet	B-Application
censorship	I-Application
represented	O
by	O
Tor	B-Application
and	O
UltraSurf	B-Application
were	O
at	O
base	O
philosophical	O
and	O
simply	O
different	O
approaches	O
to	O
censorship	B-Application
circumvention	I-Application
.	O
</s>
<s>
A	O
top-secret	O
NSA	O
presentation	O
revealed	O
as	O
part	O
of	O
the	O
2013	O
global	O
surveillance	O
disclosures	O
dismisses	O
this	O
response	O
by	O
UltraSurf	B-Application
as	O
"	O
all	O
talk	O
and	O
no	O
show	O
"	O
.	O
</s>
<s>
Due	O
to	O
restrictions	O
imposed	O
by	O
some	O
organizations	O
,	O
McAfee	B-Operating_System
VirusScan	I-Operating_System
is	O
flagging	O
some	O
Ultrasurf	B-Application
versions	O
as	O
a	O
potentially	B-Application
unwanted	I-Application
program	I-Application
,	O
avoiding	O
its	O
execution	O
on	O
those	O
machines	O
.	O
</s>
