<s>
In	O
computer	B-Architecture
networking	I-Architecture
,	O
a	O
media	B-Protocol
access	I-Protocol
control	I-Protocol
attack	I-Protocol
or	O
MAC	B-Protocol
flooding	I-Protocol
is	O
a	O
technique	O
employed	O
to	O
compromise	O
the	O
security	O
of	O
network	B-Protocol
switches	I-Protocol
.	O
</s>
<s>
The	O
attack	O
works	O
by	O
forcing	O
legitimate	O
MAC	B-Protocol
table	I-Protocol
contents	O
out	O
of	O
the	O
switch	O
and	O
forcing	O
a	O
unicast	O
flooding	O
behavior	O
potentially	O
sending	O
sensitive	O
information	O
to	O
portions	O
of	O
the	O
network	O
where	O
it	O
is	O
not	O
normally	O
intended	O
to	O
go	O
.	O
</s>
<s>
Switches	O
maintain	O
a	O
MAC	B-Protocol
table	I-Protocol
that	O
maps	O
individual	O
MAC	O
addresses	O
on	O
the	O
network	O
to	O
the	O
physical	O
ports	O
on	O
the	O
switch	O
.	O
</s>
<s>
This	O
allows	O
the	O
switch	O
to	O
direct	O
data	O
out	O
of	O
the	O
physical	O
port	O
where	O
the	O
recipient	O
is	O
located	O
,	O
as	O
opposed	O
to	O
indiscriminately	O
broadcasting	B-Operating_System
the	O
data	O
out	O
of	O
all	O
ports	O
as	O
an	O
Ethernet	B-Protocol
hub	I-Protocol
does	O
.	O
</s>
<s>
The	O
advantage	O
of	O
this	O
method	O
is	O
that	O
data	O
is	O
bridged	B-Protocol
exclusively	O
to	O
the	O
network	B-Protocol
segment	I-Protocol
containing	O
the	O
computer	O
that	O
the	O
data	O
is	O
specifically	O
destined	O
for	O
.	O
</s>
<s>
In	O
a	O
typical	O
MAC	B-Protocol
flooding	I-Protocol
attack	O
,	O
a	O
switch	O
is	O
fed	O
many	O
Ethernet	B-Protocol
frames	I-Protocol
,	O
each	O
containing	O
different	O
source	O
MAC	O
addresses	O
,	O
by	O
the	O
attacker	O
.	O
</s>
<s>
The	O
intention	O
is	O
to	O
consume	O
the	O
limited	O
memory	B-General_Concept
set	O
aside	O
in	O
the	O
switch	O
to	O
store	O
the	O
MAC	O
address	O
table	O
.	O
</s>
<s>
The	O
effect	O
of	O
this	O
attack	O
may	O
vary	O
across	O
implementations	O
,	O
however	O
the	O
desired	O
effect	O
(	O
by	O
the	O
attacker	O
)	O
is	O
to	O
force	O
legitimate	O
MAC	O
addresses	O
out	O
of	O
the	O
MAC	O
address	O
table	O
,	O
causing	O
significant	O
quantities	O
of	O
incoming	O
frames	O
to	O
be	O
flooded	B-Protocol
out	O
on	O
all	O
ports	O
.	O
</s>
<s>
It	O
is	O
from	O
this	O
flooding	O
behavior	O
that	O
the	O
MAC	B-Protocol
flooding	I-Protocol
attack	O
gets	O
its	O
name	O
.	O
</s>
<s>
After	O
launching	O
a	O
successful	O
MAC	B-Protocol
flooding	I-Protocol
attack	O
,	O
a	O
malicious	O
user	O
can	O
use	O
a	O
packet	B-Protocol
analyzer	I-Protocol
to	O
capture	O
sensitive	O
data	O
being	O
transmitted	O
between	O
other	O
computers	O
,	O
which	O
would	O
not	O
be	O
accessible	O
were	O
the	O
switch	O
operating	O
normally	O
.	O
</s>
<s>
The	O
attacker	O
may	O
also	O
follow	O
up	O
with	O
an	O
ARP	O
spoofing	O
attack	O
which	O
will	O
allow	O
them	O
to	O
retain	O
access	O
to	O
privileged	O
data	O
after	O
switches	O
recover	O
from	O
the	O
initial	O
MAC	B-Protocol
flooding	I-Protocol
attack	O
.	O
</s>
<s>
MAC	B-Protocol
flooding	I-Protocol
can	O
also	O
be	O
used	O
as	O
a	O
rudimentary	O
VLAN	B-Protocol
hopping	I-Protocol
attack	O
.	O
</s>
<s>
To	O
prevent	O
MAC	B-Protocol
flooding	I-Protocol
attacks	O
,	O
network	O
operators	O
usually	O
rely	O
on	O
the	O
presence	O
of	O
one	O
or	O
more	O
features	O
in	O
their	O
network	O
equipment	O
:	O
</s>
