<s>
NPF	B-Protocol
is	O
a	O
BSD	O
licensed	O
stateful	O
packet	B-Protocol
filter	I-Protocol
,	O
a	O
central	O
piece	O
of	O
software	O
for	O
firewalling	B-Application
.	O
</s>
<s>
It	O
is	O
comparable	O
to	O
iptables	B-Application
,	O
ipfw	B-Protocol
,	O
ipfilter	B-Protocol
and	O
PF	B-Protocol
.	O
</s>
<s>
NPF	B-Protocol
is	O
developed	O
on	O
NetBSD	B-Device
.	O
</s>
<s>
NPF	B-Protocol
was	O
primarily	O
written	O
by	O
Mindaugas	O
Rasiukevicius	O
.	O
</s>
<s>
NPF	B-Protocol
first	O
appeared	O
in	O
the	O
NetBSD	B-Device
6.0	O
release	O
in	O
2012	O
.	O
</s>
<s>
NPF	B-Protocol
is	O
designed	O
for	O
high	O
performance	O
on	O
SMP	B-Operating_System
systems	O
and	O
for	O
easy	O
extensibility	O
.	O
</s>
<s>
It	O
supports	O
various	O
forms	O
of	O
Network	B-Protocol
Address	I-Protocol
Translation	I-Protocol
(	O
NAT	O
)	O
,	O
stateful	O
packet	O
inspection	O
,	O
tree	O
and	O
hash	O
tables	O
for	O
IP	O
sets	O
,	O
bytecode	O
(	O
BPF	B-Protocol
or	O
n-code	O
)	O
for	O
custom	O
filter	O
rules	O
and	O
other	O
features	O
.	O
</s>
<s>
NPF	B-Protocol
has	O
extension	O
framework	O
for	O
supporting	O
custom	O
modules	O
.	O
</s>
<s>
Features	O
such	O
as	O
packet	O
logging	O
,	O
traffic	O
normalization	O
,	O
random	O
blocking	O
are	O
provided	O
as	O
NPF	B-Protocol
extensions	O
.	O
</s>
