<s>
BSD	B-Operating_System
Authentication	I-Operating_System
,	O
otherwise	O
known	O
as	O
BSD	B-Operating_System
Auth	I-Operating_System
,	O
is	O
an	O
authentication	O
framework	B-Architecture
and	O
software	O
API	B-General_Concept
employed	O
by	O
OpenBSD	B-Operating_System
and	O
accompanying	O
software	O
such	O
as	O
OpenSSH	B-Language
.	O
</s>
<s>
It	O
originated	O
with	O
BSD/OS	B-Operating_System
,	O
and	O
although	O
the	O
specification	O
and	O
implementation	O
were	O
donated	O
to	O
the	O
FreeBSD	B-Operating_System
project	I-Operating_System
by	O
BSDi	O
,	O
OpenBSD	B-Operating_System
chose	O
to	O
adopt	O
the	O
framework	B-Architecture
in	O
release	O
2.9	O
.	O
</s>
<s>
Pluggable	B-Application
Authentication	I-Application
Modules	I-Application
(	O
PAM	O
)	O
serves	O
a	O
similar	O
purpose	O
on	O
other	O
operating	O
systems	O
such	O
as	O
Linux	B-Application
,	O
FreeBSD	B-Operating_System
and	O
NetBSD	B-Device
.	O
</s>
<s>
BSD	B-Operating_System
Auth	I-Operating_System
performs	O
authentication	O
by	O
executing	O
scripts	O
or	O
programs	O
as	O
separate	O
processes	O
from	O
the	O
one	O
requiring	O
the	O
authentication	O
.	O
</s>
<s>
This	O
prevents	O
the	O
child	O
authentication	O
process	B-Operating_System
from	O
interfering	O
with	O
the	O
parent	O
except	O
through	O
a	O
narrowly	O
defined	O
inter-process	B-Operating_System
communication	I-Operating_System
API	B-General_Concept
,	O
a	O
technique	O
inspired	O
by	O
the	O
principle	O
of	O
least	O
privilege	O
and	O
known	O
as	O
privilege	O
separation	O
.	O
</s>
<s>
This	O
behaviour	O
has	O
significant	O
security	O
benefits	O
,	O
notably	O
improved	O
fail-safeness	O
of	O
software	O
,	O
and	O
robustness	O
against	O
malicious	O
and	O
accidental	O
software	B-Error_Name
bugs	I-Error_Name
.	O
</s>
