<s>
Shadowsocks	B-Language
is	O
a	O
free	B-License
and	I-License
open-source	I-License
encryption	B-Protocol
protocol	I-Protocol
project	O
,	O
widely	O
used	O
in	O
China	O
to	O
circumvent	O
Internet	O
censorship	O
.	O
</s>
<s>
Shadowsocks	B-Language
is	O
not	O
a	O
proxy	O
on	O
its	O
own	O
,	O
but	O
(	O
typically	O
)	O
is	O
the	O
client	O
software	O
to	O
help	O
connect	O
to	O
a	O
third-party	O
SOCKS5	B-Application
proxy	O
,	O
which	O
is	O
similar	O
to	O
a	O
Secure	O
Shell	O
(	O
SSH	O
)	O
tunnel	O
.	O
</s>
<s>
Unlike	O
an	O
SSH	O
tunnel	O
,	O
shadowsocks	B-Language
can	O
also	O
proxy	O
User	B-Protocol
Datagram	I-Protocol
Protocol	I-Protocol
(	O
UDP	O
)	O
traffic	O
.	O
</s>
<s>
On	O
22	O
August	O
2015	O
,	O
"	O
clowwindy	O
"	O
announced	O
in	O
a	O
GitHub	B-Application
thread	O
that	O
they	O
had	O
been	O
contacted	O
by	O
the	O
police	O
and	O
could	O
no	O
longer	O
maintain	O
the	O
project	O
.	O
</s>
<s>
Three	O
days	O
later	O
,	O
on	O
25August	O
,	O
another	O
proxy	O
application	O
,	O
GoAgent	B-Operating_System
,	O
also	O
had	O
its	O
GitHub	B-Application
repository	O
removed	O
.	O
</s>
<s>
The	O
removal	O
of	O
the	O
projects	O
got	O
media	O
's	O
attention	O
,	O
with	O
news	O
outlets	O
speculating	O
about	O
the	O
possible	O
connection	O
between	O
the	O
takedowns	O
and	O
a	O
distributed-denial-of-service	O
attack	O
targeting	O
GitHub	B-Application
that	O
happened	O
several	O
days	O
later	O
.	O
</s>
<s>
The	O
original	O
Python	O
implementation	O
can	O
still	O
be	O
installed	O
with	O
Pip	B-Application
(	O
package	O
manager	O
)	O
,	O
but	O
the	O
contents	O
of	O
its	O
GitHub	B-Application
repository	O
have	O
been	O
removed	O
.	O
</s>
<s>
There	O
are	O
also	O
client-only	O
implementations	O
available	O
for	O
Windows	O
(	O
shadowsocks-win	O
)	O
,	O
macOS	O
(	O
ShadowsocksX-NG	O
)	O
,	O
Android	O
(	O
shadowsocks-android	O
)	O
,	O
and	O
iOS	O
(	O
Wingy	O
)	O
.	O
</s>
<s>
Many	O
clients	O
,	O
including	O
shadowsocks-win	O
and	O
shadowsocks-android	O
,	O
support	O
redirecting	O
all	O
system	O
traffic	O
over	O
Shadowsocks	B-Language
,	O
not	O
just	O
applications	O
that	O
have	O
been	O
explicitly	O
configured	O
to	O
do	O
so	O
,	O
allowing	O
Shadowsocks	B-Language
to	O
be	O
used	O
similarly	O
to	O
a	O
VPN	B-Application
.	O
</s>
<s>
If	O
an	O
application	O
does	O
n't	O
support	O
proxy	O
servers	O
,	O
a	O
proxifier	O
can	O
be	O
used	O
to	O
redirect	O
the	O
application	O
to	O
the	O
Shadowsocks	B-Language
client	O
.	O
</s>
<s>
Some	O
proxifiers	O
,	O
such	O
as	O
Proxycap	O
,	O
support	O
Shadowsocks	B-Language
directly	O
,	O
thus	O
avoiding	O
the	O
need	O
for	O
a	O
Shadowsocks	B-Language
client	O
,	O
but	O
some	O
require	O
a	O
client	O
.	O
</s>
<s>
Net::Shadowsocks	O
is	O
name	O
of	O
the	O
Perl	O
implementation	O
of	O
Shadowsocks	B-Language
protocol	O
client	O
and	O
server	O
available	O
on	O
CPAN	B-Language
.	O
</s>
<s>
ShadowsocksR	O
is	O
a	O
fork	B-Application
of	O
the	O
original	O
Shadowsocks	B-Language
project	O
,	O
claimed	O
to	O
be	O
superior	O
in	O
terms	O
of	O
security	O
and	O
stability	O
.	O
</s>
<s>
Upon	O
release	O
,	O
it	O
was	O
found	O
to	O
violate	O
the	O
License	B-License
by	O
not	O
having	O
the	O
source	O
code	O
of	O
the	O
C#	O
client	O
available	O
.	O
</s>
<s>
Shadowsocks	B-Language
is	O
currently	O
under	O
development	O
,	O
while	O
development	O
of	O
ShadowsocksR	O
has	O
stopped	O
.	O
</s>
<s>
Shadowsocks	B-Language
is	O
similar	O
to	O
The	O
Tor	O
Project	O
's	O
Pluggable	O
Transport	O
(	O
PT	O
)	O
idea	O
.	O
</s>
<s>
They	O
also	O
both	O
use	O
a	O
socks	B-Application
proxy	I-Application
interface	O
.	O
</s>
<s>
Whereas	O
Shadowsocks	B-Language
is	O
simpler	O
,	O
Obfs4	O
used	O
in	O
PT	O
is	O
more	O
obfuscated	O
.	O
</s>
<s>
Unlike	O
Obfs4	O
,	O
Shadowsocks	B-Language
is	O
not	O
resistant	O
to	O
Active	O
Probing	O
.	O
</s>
<s>
The	O
most	O
similar	O
PT	O
to	O
Shadowsocks	B-Language
is	O
Obfs3	O
.	O
</s>
