<s>
An	O
Internet	B-Protocol
filter	I-Protocol
is	O
software	O
that	O
restricts	O
or	O
controls	O
the	O
content	O
an	O
Internet	O
user	O
is	O
capable	O
to	O
access	O
,	O
especially	O
when	O
utilized	O
to	O
restrict	O
material	O
delivered	O
over	O
the	O
Internet	O
via	O
the	O
Web	O
,	O
Email	O
,	O
or	O
other	O
means	O
.	O
</s>
<s>
Content-control	B-Protocol
software	I-Protocol
determines	O
what	O
content	O
will	O
be	O
available	O
or	O
be	O
blocked	O
.	O
</s>
<s>
Such	O
restrictions	O
can	O
be	O
applied	O
at	O
various	O
levels	O
:	O
a	O
government	O
can	O
attempt	O
to	O
apply	O
them	O
nationwide	O
(	O
see	O
Internet	B-Application
censorship	I-Application
)	O
,	O
or	O
they	O
can	O
,	O
for	O
example	O
,	O
be	O
applied	O
by	O
an	O
Internet	O
service	O
provider	O
to	O
its	O
clients	O
,	O
by	O
an	O
employer	O
to	O
its	O
personnel	O
,	O
by	O
a	O
school	O
to	O
its	O
students	O
,	O
by	O
a	O
library	O
to	O
its	O
visitors	O
,	O
by	O
a	O
parent	O
to	O
a	O
child	O
's	O
computer	O
,	O
or	O
by	O
an	O
individual	O
users	O
to	O
their	O
own	O
computers	O
.	O
</s>
<s>
When	O
imposed	O
without	O
the	O
consent	O
of	O
the	O
user	O
,	O
content	O
control	O
can	O
be	O
characterised	O
as	O
a	O
form	O
of	O
internet	B-Application
censorship	I-Application
.	O
</s>
<s>
Some	O
content-control	B-Protocol
software	I-Protocol
includes	O
time	O
control	O
functions	O
that	O
empowers	O
parents	O
to	O
set	O
the	O
amount	O
of	O
time	O
that	O
child	O
may	O
spend	O
accessing	O
the	O
Internet	O
or	O
playing	O
games	O
or	O
other	O
computer	O
activities	O
.	O
</s>
<s>
In	O
Cuba	O
,	O
if	O
a	O
computer	O
user	O
at	O
a	O
government-controlled	O
Internet	O
cafe	O
types	O
certain	O
words	O
,	O
the	O
word	B-Protocol
processor	I-Protocol
or	O
web	B-Application
browser	I-Application
is	O
automatically	O
closed	O
,	O
and	O
a	O
"	O
state	O
security	O
"	O
warning	O
is	O
given	O
.	O
</s>
<s>
The	O
term	O
"	O
content	O
control	O
"	O
is	O
used	O
on	O
occasion	O
by	O
CNN	B-Architecture
,	O
Playboy	O
magazine	O
,	O
the	O
San	O
Francisco	O
Chronicle	O
,	O
and	O
The	O
New	O
York	O
Times	O
.	O
</s>
<s>
However	O
,	O
several	O
other	O
terms	O
,	O
including	O
"	O
content	B-Protocol
filtering	I-Protocol
software	I-Protocol
"	O
,	O
"	O
filtering	O
proxy	B-Application
servers	I-Application
"	O
,	O
"	O
secure	B-Protocol
web	I-Protocol
gateways	I-Protocol
"	O
,	O
"	O
censorware	B-Protocol
"	O
,	O
"	O
content	O
security	O
and	O
control	O
"	O
,	O
"	O
web	B-Protocol
filtering	I-Protocol
software	I-Protocol
"	O
,	O
"	O
content-censoring	B-Protocol
software	I-Protocol
"	O
,	O
and	O
"	O
content-blocking	B-Protocol
software	I-Protocol
"	O
,	O
are	O
often	O
used	O
.	O
</s>
<s>
"	O
Nannyware	B-Protocol
"	O
has	O
also	O
been	O
used	O
in	O
both	O
product	O
marketing	O
and	O
by	O
the	O
media	O
.	O
</s>
<s>
Industry	O
research	O
company	O
Gartner	O
uses	O
"	O
secure	B-Protocol
web	I-Protocol
gateway	I-Protocol
"	O
(	O
SWG	O
)	O
to	O
describe	O
the	O
market	O
segment	O
.	O
</s>
<s>
Companies	O
that	O
make	O
products	O
that	O
selectively	O
block	O
Web	O
sites	O
do	O
not	O
refer	O
to	O
these	O
products	O
as	O
censorware	B-Protocol
,	O
and	O
prefer	O
terms	O
such	O
as	O
"	O
Internet	B-Protocol
filter	I-Protocol
"	O
or	O
"	O
URL	O
Filter	O
"	O
;	O
in	O
the	O
specialized	O
case	O
of	O
software	O
specifically	O
designed	O
to	O
allow	O
parents	O
to	O
monitor	O
and	O
restrict	O
the	O
access	O
of	O
their	O
children	O
,	O
"	O
parental	O
control	O
software	O
"	O
is	O
also	O
used	O
.	O
</s>
<s>
Internet	B-Protocol
filters	I-Protocol
,	O
parental	O
control	O
software	O
,	O
and/or	O
accountability	O
software	O
may	O
also	O
be	O
combined	O
into	O
one	O
product	O
.	O
</s>
<s>
Those	O
critical	O
of	O
such	O
software	O
,	O
however	O
,	O
use	O
the	O
term	O
"	O
censorware	B-Protocol
"	O
freely	O
:	O
consider	O
the	O
Censorware	B-Protocol
Project	O
,	O
for	O
example	O
.	O
</s>
<s>
The	O
use	O
of	O
the	O
term	O
"	O
censorware	B-Protocol
"	O
in	O
editorials	O
criticizing	O
makers	O
of	O
such	O
software	O
is	O
widespread	O
and	O
covers	O
many	O
different	O
varieties	O
and	O
applications	O
:	O
Xeni	O
Jardin	O
used	O
the	O
term	O
in	O
a	O
9	O
March	O
2006	O
editorial	O
in	O
The	O
New	O
York	O
Times	O
when	O
discussing	O
the	O
use	O
of	O
American-made	O
filtering	B-Protocol
software	I-Protocol
to	O
suppress	O
content	O
in	O
China	O
;	O
in	O
the	O
same	O
month	O
a	O
high	O
school	O
student	O
used	O
the	O
term	O
to	O
discuss	O
the	O
deployment	O
of	O
such	O
software	O
in	O
his	O
school	O
district	O
.	O
</s>
<s>
In	O
general	O
,	O
outside	O
of	O
editorial	O
pages	O
as	O
described	O
above	O
,	O
traditional	O
newspapers	O
do	O
not	O
use	O
the	O
term	O
"	O
censorware	B-Protocol
"	O
in	O
their	O
reporting	O
,	O
preferring	O
instead	O
to	O
use	O
less	O
overtly	O
controversial	O
terms	O
such	O
as	O
"	O
content	B-Protocol
filter	I-Protocol
"	O
,	O
"	O
content	O
control	O
"	O
,	O
or	O
"	O
web	B-Protocol
filtering	I-Protocol
"	O
;	O
The	O
New	O
York	O
Times	O
and	O
The	O
Wall	O
Street	O
Journal	O
both	O
appear	O
to	O
follow	O
this	O
practice	O
.	O
</s>
<s>
On	O
the	O
other	O
hand	O
,	O
Web-based	O
newspapers	O
such	O
as	O
CNET	O
use	O
the	O
term	O
in	O
both	O
editorial	O
and	O
journalistic	O
contexts	O
,	O
for	O
example	O
"	O
Windows	O
Live	O
to	O
Get	O
Censorware.	O
"	O
</s>
<s>
Filters	O
can	O
be	O
implemented	O
in	O
many	O
different	O
ways	O
:	O
by	O
software	O
on	O
a	O
personal	O
computer	O
,	O
via	O
network	O
infrastructure	O
such	O
as	O
proxy	B-Application
servers	I-Application
,	O
DNS	B-Protocol
servers	O
,	O
or	O
firewalls	B-Application
that	O
provide	O
Internet	O
access	O
.	O
</s>
<s>
Browser	B-Application
based	O
content	B-Protocol
filtering	I-Protocol
solution	O
is	O
the	O
most	O
lightweight	O
solution	O
to	O
do	O
the	O
content	B-Protocol
filtering	I-Protocol
,	O
and	O
is	O
implemented	O
via	O
a	O
third	O
party	O
browser	B-Protocol
extension	I-Protocol
.	O
</s>
<s>
E-mail	O
filters	O
act	O
on	O
information	O
contained	O
in	O
the	O
mail	B-Operating_System
body	O
,	O
in	O
the	O
mail	B-Operating_System
headers	O
such	O
as	O
sender	O
and	O
subject	O
,	O
and	O
e-mail	O
attachments	O
to	O
classify	O
,	O
accept	O
,	O
or	O
reject	O
messages	O
.	O
</s>
<s>
Bayesian	B-Application
filters	I-Application
,	O
a	O
type	O
of	O
statistical	O
filter	O
,	O
are	O
commonly	O
used	O
.	O
</s>
<s>
A	O
DNS-based	O
client-side	O
filter	O
would	O
be	O
to	O
set	O
up	O
a	O
DNS	B-Protocol
Sinkhole	I-Protocol
,	O
such	O
as	O
Pi-Hole	B-Application
.	O
</s>
<s>
This	O
type	O
of	O
filter	O
is	O
implemented	O
at	O
the	O
transport	B-Architecture
layer	I-Architecture
as	O
a	O
transparent	O
proxy	O
,	O
or	O
at	O
the	O
application	B-Application
layer	I-Application
as	O
a	O
web	B-Application
proxy	I-Application
.	O
</s>
<s>
Filtering	B-Protocol
software	I-Protocol
may	O
include	O
data	B-Application
loss	I-Application
prevention	I-Application
functionality	O
to	O
filter	O
outbound	O
as	O
well	O
as	O
inbound	O
information	O
.	O
</s>
<s>
This	O
type	O
of	O
filtering	O
is	O
implemented	O
at	O
the	O
DNS	B-Protocol
layer	O
and	O
attempts	O
to	O
prevent	O
lookups	O
for	O
domains	O
that	O
do	O
not	O
fit	O
within	O
a	O
set	O
of	O
policies	O
(	O
either	O
parental	O
control	O
or	O
company	O
rules	O
)	O
.	O
</s>
<s>
Multiple	O
free	O
public	B-Operating_System
DNS	I-Operating_System
services	I-Operating_System
offer	O
filtering	O
options	O
as	O
part	O
of	O
their	O
services	O
.	O
</s>
<s>
DNS	B-Protocol
Sinkholes	I-Protocol
such	O
as	O
Pi-Hole	B-Application
can	O
be	O
also	O
be	O
used	O
for	O
this	O
purpose	O
,	O
though	O
client-side	O
only	O
.	O
</s>
<s>
Many	O
search	O
engines	O
,	O
such	O
as	O
Google	B-Application
and	O
Bing	O
offer	O
users	O
the	O
option	O
of	O
turning	O
on	O
a	O
safety	O
filter	O
.	O
</s>
<s>
Content	B-Protocol
filtering	I-Protocol
software	I-Protocol
can	O
,	O
however	O
,	O
also	O
be	O
used	O
to	O
block	O
malware	O
and	O
other	O
content	O
that	O
is	O
or	O
contains	O
hostile	O
,	O
intrusive	O
,	O
or	O
annoying	O
material	O
including	O
adware	O
,	O
spam	O
,	O
computer	O
viruses	O
,	O
worms	O
,	O
trojan	O
horses	O
,	O
and	O
spyware	O
.	O
</s>
<s>
Most	O
content	B-Protocol
control	I-Protocol
software	I-Protocol
is	O
marketed	O
to	O
organizations	O
or	O
parents	O
.	O
</s>
<s>
Over	O
blocking	O
can	O
filter	O
out	O
material	O
that	O
should	O
be	O
acceptable	O
under	O
the	O
filtering	O
policy	O
in	O
effect	O
,	O
for	O
example	O
health	O
related	O
information	O
may	O
unintentionally	O
be	O
filtered	O
along	O
with	O
porn-related	O
material	O
because	O
of	O
the	B-Application
Scunthorpe	I-Application
problem	I-Application
.	O
</s>
<s>
Content-control	B-Protocol
software	I-Protocol
was	O
mentioned	O
as	O
blocking	O
access	O
to	O
Beaver	O
College	O
before	O
its	O
name	O
change	O
to	O
Arcadia	O
University	O
.	O
</s>
<s>
In	O
the	O
United	O
States	O
,	O
the	O
First	O
Amendment	O
to	O
the	O
United	O
States	O
Constitution	O
has	O
been	O
cited	O
in	O
calls	O
to	O
criminalise	O
forced	O
internet	B-Application
censorship	I-Application
.	O
</s>
<s>
Part	O
of	O
the	O
civil	O
liberties	O
argument	O
,	O
especially	O
from	O
groups	O
like	O
the	O
Electronic	O
Frontier	O
Foundation	O
,	O
was	O
that	O
parents	O
who	O
wanted	O
to	O
block	O
sites	O
could	O
use	O
their	O
own	O
content-filtering	B-Protocol
software	I-Protocol
,	O
making	O
government	O
involvement	O
unnecessary	O
.	O
</s>
<s>
In	O
the	O
late	O
1990s	O
,	O
groups	O
such	O
as	O
the	O
Censorware	B-Protocol
Project	O
began	O
reverse-engineering	O
the	O
content-control	B-Protocol
software	I-Protocol
and	O
decrypting	O
the	O
blacklists	O
to	O
determine	O
what	O
kind	O
of	O
sites	O
the	O
software	O
blocked	O
.	O
</s>
<s>
Some	O
content-control	B-Protocol
software	I-Protocol
companies	O
responded	O
by	O
claiming	O
that	O
their	O
filtering	O
criteria	O
were	O
backed	O
by	O
intensive	O
manual	O
checking	O
.	O
</s>
<s>
The	O
Motion	O
Picture	O
Association	O
successfully	O
obtained	O
a	O
UK	O
ruling	O
enforcing	O
ISPs	O
to	O
use	O
content-control	B-Protocol
software	I-Protocol
to	O
prevent	O
copyright	O
infringement	O
by	O
their	O
subscribers	O
.	O
</s>
<s>
Many	O
types	O
of	O
content-control	B-Protocol
software	I-Protocol
have	O
been	O
shown	O
to	O
block	O
sites	O
based	O
on	O
the	O
religious	O
and	O
political	O
leanings	O
of	O
the	O
company	O
owners	O
.	O
</s>
<s>
CYBERsitter	B-Protocol
blocks	O
out	O
sites	O
like	O
National	O
Organization	O
for	O
Women	O
.	O
</s>
<s>
Nancy	O
Willard	O
,	O
an	O
academic	O
researcher	O
and	O
attorney	O
,	O
pointed	O
out	O
that	O
many	O
U.S.	O
public	O
schools	O
and	O
libraries	O
use	O
the	O
same	O
filtering	B-Protocol
software	I-Protocol
that	O
many	O
Christian	O
organizations	O
use	O
.	O
</s>
<s>
Content	O
labeling	O
may	O
be	O
considered	O
another	O
form	O
of	O
content-control	B-Protocol
software	I-Protocol
.	O
</s>
<s>
A	O
small	O
file	O
is	O
generated	O
that	O
contains	O
a	O
condensed	O
,	O
computer	O
readable	O
digest	O
of	O
this	O
description	O
that	O
can	O
then	O
be	O
used	O
by	O
content	B-Protocol
filtering	I-Protocol
software	I-Protocol
to	O
block	O
or	O
allow	O
that	O
site	O
.	O
</s>
<s>
These	O
include	O
the	O
World	O
Wide	O
Web	O
Consortium	O
's	O
Resource	O
Description	O
Framework	O
(	O
RDF	O
)	O
as	O
well	O
as	O
Platform	O
for	O
Internet	O
Content	O
Selection	O
(	O
PICS	O
)	O
labels	O
used	O
by	O
Microsoft	O
's	O
Internet	B-Application
Explorer	I-Application
Content	O
Advisor	O
.	O
</s>
<s>
Both	O
labels	O
are	O
recognized	O
by	O
a	O
wide	B-Application
variety	I-Application
of	I-Application
content-control	I-Application
software	I-Application
.	O
</s>
<s>
The	O
Voluntary	O
Content	O
Rating	O
(	O
VCR	O
)	O
system	O
was	O
devised	O
by	O
Solid	O
Oak	O
Software	O
for	O
their	O
CYBERsitter	B-Protocol
filtering	B-Protocol
software	I-Protocol
,	O
as	O
an	O
alternative	O
to	O
the	O
PICS	O
system	O
,	O
which	O
some	O
critics	O
deemed	O
too	O
complex	O
.	O
</s>
<s>
It	O
employs	O
HTML	B-Language
metadata	O
tags	O
embedded	O
within	O
web	O
page	O
documents	O
to	O
specify	O
the	O
type	O
of	O
content	O
contained	O
in	O
the	O
document	O
.	O
</s>
<s>
Wood	O
supposedly	O
bypassed	O
the	O
$84	O
million	O
filter	O
in	O
about	O
half	O
an	O
hour	O
to	O
highlight	O
problems	O
with	O
the	O
government	O
's	O
approach	O
to	O
Internet	O
content	B-Protocol
filtering	I-Protocol
.	O
</s>
<s>
The	O
use	O
of	O
Internet	B-Protocol
filters	I-Protocol
or	O
content-control	B-Protocol
software	I-Protocol
varies	O
widely	O
in	O
public	O
libraries	O
in	O
the	O
United	O
States	O
,	O
since	O
Internet	O
use	O
policies	O
are	O
established	O
by	O
the	O
local	O
library	O
board	O
.	O
</s>
<s>
Many	O
libraries	O
adopted	O
Internet	B-Protocol
filters	I-Protocol
after	O
Congress	O
conditioned	O
the	O
receipt	O
of	O
universal	O
service	O
discounts	O
on	O
the	O
use	O
of	O
Internet	B-Protocol
filters	I-Protocol
through	O
the	O
Children	O
's	O
Internet	O
Protection	O
Act	O
(	O
CIPA	O
)	O
.	O
</s>
<s>
Other	O
libraries	O
do	O
not	O
install	O
content	B-Protocol
control	I-Protocol
software	I-Protocol
,	O
believing	O
that	O
acceptable	O
use	O
policies	O
and	O
educational	O
efforts	O
address	O
the	O
issue	O
of	O
children	O
accessing	O
age-inappropriate	O
content	O
while	O
preserving	O
adult	O
users	O
 '	O
right	O
to	O
freely	O
access	O
information	O
.	O
</s>
<s>
Some	O
libraries	O
use	O
Internet	B-Protocol
filters	I-Protocol
on	O
computers	O
used	O
by	O
children	O
only	O
.	O
</s>
<s>
Some	O
libraries	O
that	O
employ	O
content-control	B-Protocol
software	I-Protocol
allow	O
the	O
software	O
to	O
be	O
deactivated	O
on	O
a	O
case-by-case	O
basis	O
on	O
application	O
to	O
a	O
librarian	O
;	O
libraries	O
that	O
are	O
subject	O
to	O
CIPA	O
are	O
required	O
to	O
have	O
a	O
policy	O
that	O
allows	O
adults	O
to	O
request	O
that	O
the	O
filter	O
be	O
disabled	O
without	O
having	O
to	O
explain	O
the	O
reason	O
for	O
their	O
request	O
.	O
</s>
<s>
Many	O
legal	O
scholars	O
believe	O
that	O
a	O
number	O
of	O
legal	O
cases	O
,	O
in	O
particular	O
Reno	O
v	O
.	O
American	O
Civil	O
Liberties	O
Union	O
,	O
established	O
that	O
the	O
use	O
of	O
content-control	B-Protocol
software	I-Protocol
in	O
libraries	O
is	O
a	O
violation	O
of	O
the	O
First	O
Amendment	O
.	O
</s>
<s>
The	O
Children	O
's	O
Internet	O
Protection	O
Act	O
 [ CIPA ] 	O
and	O
the	O
June	O
2003	O
case	O
United	O
States	O
v	O
.	O
American	O
Library	O
Association	O
found	O
CIPA	O
constitutional	O
as	O
a	O
condition	O
placed	O
on	O
the	O
receipt	O
of	O
federal	O
funding	O
,	O
stating	O
that	O
First	O
Amendment	O
concerns	O
were	O
dispelled	O
by	O
the	O
law	O
's	O
provision	O
that	O
allowed	O
adult	O
library	O
users	O
to	O
have	O
the	O
filtering	B-Protocol
software	I-Protocol
disabled	O
,	O
without	O
having	O
to	O
explain	O
the	O
reasons	O
for	O
their	O
request	O
.	O
</s>
<s>
The	O
Washington	O
State	O
Supreme	O
Court	O
ruled	O
that	O
NCRL	O
's	O
internet	B-Protocol
filtering	I-Protocol
policy	O
did	O
not	O
violate	O
Article	O
I	O
,	O
Section	O
5	O
of	O
the	O
Washington	O
State	O
Constitution	O
.	O
</s>
<s>
In	O
March	O
2007	O
,	O
Virginia	O
passed	O
a	O
law	O
similar	O
to	O
CIPA	O
that	O
requires	O
public	O
libraries	O
receiving	O
state	O
funds	O
to	O
use	O
content-control	B-Protocol
software	I-Protocol
.	O
</s>
<s>
Content	B-Protocol
filtering	I-Protocol
in	O
general	O
can	O
"	O
be	O
bypassed	O
entirely	O
by	O
tech-savvy	O
individuals.	O
"	O
</s>
<s>
Some	O
software	O
may	O
be	O
bypassed	O
successfully	O
by	O
using	O
alternative	O
protocols	O
such	O
as	O
FTP	B-Protocol
or	O
telnet	B-Protocol
or	O
HTTPS	B-Protocol
,	O
conducting	O
searches	O
in	O
a	O
different	O
language	O
,	O
using	O
a	O
proxy	B-Application
server	I-Application
or	O
a	O
circumventor	O
such	O
as	O
Psiphon	B-Application
.	O
</s>
<s>
Also	O
cached	O
web	O
pages	O
returned	O
by	O
Google	B-Application
or	O
other	O
searches	O
could	O
bypass	O
some	O
controls	O
as	O
well	O
.	O
</s>
<s>
Some	O
of	O
the	O
more	O
poorly	O
designed	O
programs	O
can	O
be	O
shut	O
down	O
by	O
killing	O
their	O
processes	O
:	O
for	O
example	O
,	O
in	O
Microsoft	B-Application
Windows	I-Application
through	O
the	O
Windows	O
Task	B-General_Concept
Manager	I-General_Concept
,	O
or	O
in	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
using	O
Force	O
Quit	O
or	O
Activity	O
Monitor	O
.	O
</s>
<s>
Numerous	O
workarounds	O
and	O
counters	O
to	O
workarounds	O
from	O
content-control	B-Protocol
software	I-Protocol
creators	O
exist	O
.	O
</s>
<s>
Google	B-Application
services	O
are	O
often	O
blocked	O
by	O
filters	O
,	O
but	O
these	O
may	O
most	O
often	O
be	O
bypassed	O
by	O
using	O
https://	O
in	O
place	O
of	O
http://	B-Protocol
since	O
content	B-Protocol
filtering	I-Protocol
software	I-Protocol
is	O
not	O
able	O
to	O
interpret	O
content	O
under	O
secure	O
connections	O
(	O
in	O
this	O
case	O
SSL	O
)	O
.	O
</s>
<s>
An	O
encrypted	O
VPN	B-Application
can	O
be	O
used	O
as	O
means	O
of	O
bypassing	O
content	B-Protocol
control	I-Protocol
software	I-Protocol
,	O
especially	O
if	O
the	O
content	B-Protocol
control	I-Protocol
software	I-Protocol
is	O
installed	O
on	O
an	O
Internet	O
gateway	O
or	O
firewall	B-Application
.	O
</s>
<s>
Other	O
ways	O
to	O
bypass	O
a	O
content	O
control	O
filter	O
include	O
translation	O
sites	O
and	O
establishing	B-Protocol
a	I-Protocol
remote	I-Protocol
connection	I-Protocol
with	O
an	O
uncensored	O
device	O
.	O
</s>
<s>
Mac	B-Application
OS	I-Application
X	I-Application
v10.4	I-Application
offers	O
parental	O
controls	O
for	O
several	O
applications	O
(	O
Mail	B-Operating_System
,	O
Finder	B-Application
,	O
iChat	B-Protocol
,	O
Safari	B-Application
&	O
Dictionary	B-Operating_System
)	O
.	O
</s>
<s>
Microsoft	O
's	O
Windows	B-Application
Vista	I-Application
operating	I-Application
system	I-Application
also	O
includes	O
content-control	B-Protocol
software	I-Protocol
.	O
</s>
<s>
Content	B-Protocol
filtering	I-Protocol
technology	O
exists	O
in	O
two	O
major	O
forms	O
:	O
application	O
gateway	O
or	O
packet	B-Application
inspection	I-Application
.	O
</s>
<s>
For	O
HTTP	B-Protocol
access	O
the	O
application	O
gateway	O
is	O
called	O
a	O
web-proxy	O
or	O
just	O
a	O
proxy	O
.	O
</s>
<s>
Packet	B-Application
inspection	I-Application
filters	O
do	O
not	O
initially	O
interfere	O
with	O
the	O
connection	O
to	O
the	O
server	O
but	O
inspect	O
the	O
data	O
in	O
the	O
connection	O
as	O
it	O
goes	O
past	O
,	O
at	O
some	O
point	O
the	O
filter	O
may	O
decide	O
that	O
the	O
connection	O
is	O
to	O
be	O
filtered	O
and	O
it	O
will	O
then	O
disconnect	O
it	O
by	O
injecting	O
a	O
TCP-Reset	O
or	O
similar	O
faked	O
packet	O
.	O
</s>
<s>
The	O
two	O
techniques	O
can	O
be	O
used	O
together	O
with	O
the	O
packet	O
filter	O
monitoring	O
a	O
link	O
until	O
it	O
sees	O
an	O
HTTP	B-Protocol
connection	O
starting	O
to	O
an	O
IP	O
address	O
that	O
has	O
content	O
that	O
needs	O
filtering	O
.	O
</s>
<s>
Gateway-based	O
content	B-Protocol
control	I-Protocol
software	I-Protocol
may	O
be	O
more	O
difficult	O
to	O
bypass	O
than	O
desktop	O
software	O
as	O
the	O
user	O
does	O
not	O
have	O
physical	O
access	O
to	O
the	O
filtering	O
device	O
.	O
</s>
