<s>
firewalld	B-Application
is	O
a	O
firewall	B-Application
management	O
tool	O
for	O
Linux	B-Application
operating	I-Application
systems	I-Application
.	O
</s>
<s>
It	O
provides	O
firewall	B-Application
features	O
by	O
acting	O
as	O
a	O
front-end	O
for	O
the	O
Linux	B-Application
kernel	O
's	O
netfilter	B-Application
framework	O
.	O
</s>
<s>
firewalld	B-Application
's	O
current	O
default	O
backend	O
is	O
nftables	B-Application
.	O
</s>
<s>
Prior	O
to	O
v0.6.0	O
,	O
iptables	B-Application
was	O
the	O
default	O
backend	O
.	O
</s>
<s>
Through	O
its	O
abstractions	O
,	O
firewalld	B-Application
acts	O
as	O
an	O
alternative	O
to	O
nft	O
and	O
iptables	B-Application
command	O
line	O
programs	O
.	O
</s>
<s>
The	O
name	O
firewalld	B-Application
adheres	O
to	O
the	O
Unix	B-Application
convention	O
of	O
naming	O
system	B-Operating_System
daemons	I-Operating_System
by	O
appending	O
the	O
letter	O
"	O
d	O
"	O
.	O
</s>
<s>
firewalld	B-Application
is	O
written	O
in	O
Python	B-Language
.	O
</s>
<s>
It	O
was	O
intended	O
to	O
be	O
ported	O
to	O
C++	B-Language
,	O
but	O
the	O
porting	O
project	O
was	O
abandoned	O
in	O
January	O
2015	O
.	O
</s>
<s>
firewalld	B-Application
supports	O
both	O
IPv4	B-Protocol
and	O
IPv6	B-Protocol
networks	O
and	O
can	O
administer	O
separate	O
firewall	B-Application
zones	O
with	O
varying	O
degrees	O
of	O
trust	O
as	O
defined	O
in	O
zone	O
profiles	O
.	O
</s>
<s>
Administrators	O
can	O
configure	O
Network	B-Protocol
Manager	I-Protocol
to	O
automatically	O
switch	O
zone	O
profiles	O
based	O
on	O
known	O
Wi-Fi	O
(	O
wireless	O
)	O
and	O
Ethernet	O
(	O
wired	O
)	O
networks	O
,	O
but	O
firewalld	B-Application
cannot	O
do	O
this	O
on	O
its	O
own	O
.	O
</s>
<s>
Services	O
and	O
applications	O
can	O
use	O
the	O
D-Bus	B-Language
interface	O
to	O
query	O
and	O
configure	O
the	O
firewall	B-Application
.	O
</s>
<s>
firewalld	B-Application
supports	O
timed	O
rules	O
,	O
meaning	O
the	O
number	O
of	O
connections	O
(	O
or	O
"	O
hits	O
"	O
)	O
to	O
a	O
service	O
can	O
be	O
limited	O
globally	O
.	O
</s>
<s>
firewalld	B-Application
's	O
command	O
syntax	O
is	O
similar	O
to	O
but	O
more	O
verbose	O
than	O
other	O
iptables	B-Application
front-ends	O
like	O
Ubuntu	B-Operating_System
's	O
Uncomplicated	B-Language
Firewall	I-Language
(	O
ufw	O
)	O
.	O
</s>
<s>
The	O
command-line	O
interface	O
allows	O
managing	O
firewall	B-Application
rulesets	O
for	O
protocol	O
,	O
ports	O
,	O
source	O
and	O
destination	O
;	O
or	O
predefined	O
services	O
by	O
name	O
.	O
</s>
<s>
Services	O
are	O
defined	O
as	O
XML	B-Protocol
files	O
containing	O
port	O
-	O
and	O
protocol-mappings	O
,	O
and	O
optionally	O
extra	O
information	O
like	O
specifying	O
subnets	B-Protocol
and	O
listing	O
required	O
Kernel	O
helper	O
modules	O
.	O
</s>
<s>
The	O
syntax	O
resembles	O
that	O
of	O
systemd	B-Application
's	O
service	O
files	O
.	O
</s>
<s>
A	O
simple	O
service	O
file	O
for	O
a	O
web	O
server	O
listening	O
on	O
TCP	B-Protocol
port	O
443	O
might	O
look	O
like	O
this	O
:	O
</s>
<s>
firewalld	B-Application
v0.9.0	O
added	O
native	O
support	O
for	O
forward	O
and	O
output	O
forwarding	O
via	O
policy	O
objects	O
.	O
</s>
<s>
Policies	O
support	O
most	O
firewalld	B-Application
primitives	O
available	O
to	O
zones	O
:	O
services	O
,	O
ports	O
,	O
forward-ports	O
,	O
masquerade	O
,	O
rich	O
rules	O
,	O
etc	O
.	O
</s>
<s>
By	O
default	O
firewalld	B-Application
does	O
not	O
block	O
outbound	O
traffic	O
as	O
required	O
by	O
standards	O
such	O
as	O
NIST	O
800-171	O
and	O
800-53	O
.	O
</s>
<s>
firewall-config	O
is	O
a	O
graphical	O
front-end	O
that	O
is	O
optionally	O
included	O
with	O
firewalld	B-Application
,	O
with	O
support	O
for	O
most	O
of	O
its	O
features	O
.	O
</s>
<s>
firewall-applet	O
is	O
a	O
small	O
status	O
indicator	O
utility	O
that	O
is	O
optionally	O
included	O
with	O
firewalld	B-Application
.	O
</s>
<s>
It	O
can	O
provide	O
firewall	B-Application
event	O
log	O
notifications	O
as	O
well	O
as	O
a	O
quick	O
way	O
to	O
open	O
firewall-config	O
.	O
</s>
<s>
firewall-applet	O
was	O
ported	O
from	O
the	O
GTK+	B-Application
to	O
the	O
Qt	B-Language
framework	I-Language
in	O
the	O
summer	O
of	O
2015	O
following	O
the	O
GNOME	B-Application
Desktop	I-Application
’s	O
deprecation	O
of	O
system	O
tray	O
icons	O
.	O
</s>
<s>
firewalld	B-Application
ships	O
by	O
default	O
on	O
the	O
following	O
Linux	B-Application
distributions	O
:	O
</s>
<s>
firewalld	B-Application
is	O
enabled	O
by	O
default	O
in	O
all	O
of	O
these	O
distributions	O
.	O
</s>
<s>
firewalld	B-Application
is	O
also	O
available	O
as	O
one	O
of	O
many	O
firewall	B-Application
options	O
in	O
the	O
package	O
repository	O
of	O
many	O
other	O
popular	O
distributions	O
such	O
as	O
Debian	O
or	O
Ubuntu	B-Operating_System
.	O
</s>
