<s>
Logical	B-Architecture
Unit	I-Architecture
Number	I-Architecture
Masking	I-Architecture
or	O
LUN	B-Architecture
masking	I-Architecture
is	O
an	O
authorization	O
process	O
that	O
makes	O
a	O
Logical	O
Unit	O
Number	O
available	O
to	O
some	O
hosts	B-Device
and	O
unavailable	O
to	O
other	O
hosts	B-Device
.	O
</s>
<s>
LUN	B-Architecture
Masking	I-Architecture
is	O
a	O
level	O
of	O
security	O
that	O
makes	O
a	O
LUN	O
available	O
to	O
only	O
selected	O
hosts	B-Device
and	O
unavailable	O
to	O
all	O
others	O
.	O
</s>
<s>
LUN	B-Architecture
masking	I-Architecture
is	O
mainly	O
implemented	O
at	O
the	O
host	B-Architecture
bus	I-Architecture
adapter	I-Architecture
(	O
HBA	O
)	O
level	O
.	O
</s>
<s>
The	O
security	O
benefits	O
of	O
LUN	B-Architecture
masking	I-Architecture
implemented	O
at	O
HBAs	O
are	O
limited	O
,	O
since	O
with	O
many	O
HBAs	O
it	O
is	O
possible	O
to	O
forge	B-General_Concept
source	O
addresses	O
(	O
WWNs/MACs/IPs	O
)	O
and	O
compromise	O
the	O
access	O
.	O
</s>
<s>
Many	O
storage	O
controllers	O
also	O
support	O
LUN	B-Architecture
masking	I-Architecture
.	O
</s>
<s>
When	O
LUN	B-Architecture
masking	I-Architecture
is	O
implemented	O
at	O
the	O
storage	O
controller	O
level	O
,	O
the	O
controller	O
itself	O
enforces	O
the	O
access	O
policies	O
to	O
the	O
device	O
and	O
as	O
a	O
result	O
it	O
is	O
more	O
secure	O
.	O
</s>
<s>
For	O
example	O
,	O
Windows	B-Application
servers	O
attached	O
to	O
a	O
SAN	O
will	O
,	O
under	O
some	O
conditions	O
,	O
corrupt	O
non-Windows	O
(	O
Unix	B-Application
,	O
Linux	B-Application
,	O
NetWare	B-Operating_System
)	O
volumes	O
on	O
the	O
SAN	O
by	O
attempting	O
to	O
write	O
Windows	B-Application
volume	O
labels	O
to	O
them	O
.	O
</s>
<s>
By	O
hiding	O
the	O
other	O
LUNs	O
from	O
the	O
Windows	B-Application
server	O
,	O
this	O
can	O
be	O
prevented	O
,	O
since	O
the	O
Windows	B-Application
server	O
does	O
not	O
even	O
realize	O
the	O
other	O
LUNs	O
exist	O
.	O
</s>
