<s>
netgraph	B-Device
is	O
the	O
graph	O
based	O
kernel	B-Operating_System
networking	B-Architecture
subsystem	O
of	O
FreeBSD	B-Operating_System
since	O
3.4	O
and	O
DragonFly	B-Application
BSD	I-Application
since	O
the	O
fork	O
from	O
FreeBSD	B-Operating_System
.	O
</s>
<s>
Netgraph	B-Device
provides	O
support	O
for	O
L2TP	B-Application
,	O
PPTP	B-Protocol
,	O
ATM	O
,	O
Bluetooth	B-Protocol
using	O
a	O
modular	O
set	O
of	O
nodes	O
that	O
are	O
the	O
graph	O
.	O
</s>
<s>
Netgraph	B-Device
has	O
also	O
been	O
ported	O
on	O
other	O
Operating	O
Systems	O
:	O
</s>
<s>
Netgraph	B-Device
was	O
originally	O
designed	O
and	O
implemented	O
at	O
Whistle	O
Communications	O
by	O
Julian	O
Elischer	O
and	O
Archie	O
Cobbs	O
for	O
the	O
Whistle	O
InterJet	O
small	O
office	O
router	O
product	O
.	O
</s>
<s>
The	O
purpose	O
of	O
the	O
project	O
was	O
to	O
create	O
a	O
flexible	O
framework	O
for	O
implementing	O
new	O
networking	B-Architecture
protocols	O
.	O
</s>
<s>
Key	O
requirements	O
included	O
the	O
ability	O
to	O
prototype	O
with	O
user-space	O
programs	O
while	O
still	O
retaining	O
the	O
ability	O
to	O
interact	O
with	O
data	O
flows	O
normally	O
hidden	O
within	O
the	O
kernel	B-Operating_System
.	O
</s>
