<s>
Shorewall	B-Protocol
is	O
an	O
open	B-Application
source	I-Application
firewall	B-Application
tool	O
for	O
Linux	B-Operating_System
that	O
builds	O
upon	O
the	O
Netfilter	B-Application
(	O
iptables/ipchains	O
)	O
system	O
built	O
into	O
the	O
Linux	B-Operating_System
kernel	I-Operating_System
,	O
making	O
it	O
easier	O
to	O
manage	O
more	O
complex	O
configuration	O
schemes	O
by	O
providing	O
a	O
higher	O
level	O
of	O
abstraction	O
for	O
describing	O
rules	O
using	O
text	O
files	O
.	O
</s>
<s>
It	O
is	O
not	O
a	O
daemon	B-Operating_System
since	O
it	O
does	O
not	O
run	O
continuously	O
,	O
but	O
rather	O
configures	O
rules	O
in	O
the	O
kernel	B-Operating_System
that	O
allow	O
and	O
disallow	O
traffic	O
through	O
the	O
system	O
.	O
</s>
<s>
Shorewall	B-Protocol
is	O
configured	O
through	O
a	O
group	O
of	O
plain-text	O
configuration	O
files	O
and	O
does	O
not	O
have	O
a	O
graphical	B-Application
user	I-Application
interface	I-Application
,	O
though	O
a	O
Webmin	B-Application
module	I-Application
is	O
available	O
separately	O
.	O
</s>
<s>
A	O
monitoring	O
utility	O
packaged	O
with	O
Shorewall	B-Protocol
can	O
be	O
used	O
to	O
watch	O
the	O
status	O
of	O
the	O
system	O
as	O
it	O
operates	O
and	O
to	O
assist	O
in	O
testing	O
.	O
</s>
<s>
Shorewall	B-Protocol
is	O
mainly	O
used	O
in	O
network	O
installations	O
(	O
as	O
opposed	O
to	O
a	O
personal	B-Protocol
computer	I-Protocol
firewall	I-Protocol
)	O
,	O
since	O
most	O
of	O
its	O
strength	O
lies	O
in	O
its	O
ability	O
to	O
work	O
with	O
"	O
zones	O
"	O
,	O
such	O
as	O
the	O
DMZ	B-General_Concept
or	O
a	O
'	O
net	O
 '	O
zone	O
.	O
</s>
<s>
Each	O
zone	O
would	O
then	O
have	O
different	O
rules	O
,	O
making	O
it	O
easy	O
to	O
have	O
for	O
example	O
relaxed	O
rules	O
on	O
the	O
company	O
intranet	B-General_Concept
,	O
yet	O
clamp	O
down	O
on	O
traffic	O
coming	O
in	O
from	O
the	O
Internet	O
.	O
</s>
<s>
The	O
plain-text	O
configuration	O
files	O
are	O
usually	O
well-commented	O
and	O
easy	O
to	O
use	O
,	O
though	O
Shorewall	B-Protocol
may	O
be	O
more	O
difficult	O
for	O
new	O
users	O
to	O
handle	O
than	O
other	O
firewall	B-Application
systems	O
with	O
graphical	O
front-ends	O
.	O
</s>
<s>
Starting	O
with	O
version	O
4	O
,	O
Shorewall	B-Protocol
began	O
using	O
a	O
Perl-based	O
compiler	O
frontend	O
;	O
previously	O
it	O
used	O
a	O
shell-based	O
compiler	O
frontend	O
.	O
</s>
<s>
Support	O
for	O
IPv6	B-Protocol
firewalling	O
is	O
included	O
since	O
version	O
4.2.4	O
.	O
</s>
<s>
Management	O
of	O
the	O
Shorewall	B-Protocol
project	O
was	O
handed	O
over	O
to	O
a	O
Shorewall	B-Protocol
committee	O
who	O
would	O
manage	O
the	O
future	O
direction	O
of	O
the	O
Shorewall	B-Protocol
project	O
.	O
</s>
<s>
Tom	O
Eastep	O
however	O
continues	O
to	O
be	O
a	O
major	O
contributor	O
to	O
the	O
Shorewall	B-Protocol
project	O
as	O
of	O
September	O
2020	O
.	O
</s>
