<s>
Toor	B-Operating_System
,	O
the	O
word	O
"	O
root	O
"	O
spelled	O
backwards	O
,	O
is	O
an	O
alternative	O
superuser	B-Application
account	O
in	O
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
,	O
particularly	O
BSD	B-Operating_System
and	O
variants	O
.	O
</s>
<s>
In	O
Unix	O
,	O
it	O
is	O
traditional	O
to	O
keep	O
the	O
root	O
filesystem	B-Application
as	O
small	O
as	O
reasonably	O
possible	O
,	O
moving	O
larger	O
programs	O
and	O
rapidly	O
changing	O
data	O
to	O
other	O
,	O
optional	O
parts	O
of	O
the	O
system	O
.	O
</s>
<s>
It	O
also	O
means	O
that	O
the	O
superuser	B-Application
account	O
,	O
necessary	O
for	O
repairing	O
a	O
broken	O
system	O
,	O
should	O
not	O
depend	O
on	O
any	O
programs	O
outside	O
of	O
this	O
small	O
core	O
.	O
</s>
<s>
To	O
this	O
end	O
,	O
the	O
root	B-Application
account	I-Application
is	O
often	O
configured	O
with	O
a	O
shell	B-Operating_System
which	O
is	O
small	O
,	O
efficient	O
,	O
and	O
dependable	O
,	O
but	O
awkward	O
for	O
daily	O
use	O
.	O
</s>
<s>
The	O
toor	B-Operating_System
account	O
is	O
intended	O
as	O
a	O
solution	O
to	O
this	O
problem	O
.	O
</s>
<s>
It	O
is	O
identical	O
to	O
root	O
,	O
but	O
is	O
configured	O
to	O
use	O
a	O
different	O
,	O
more	O
featureful	O
shell	B-Operating_System
.	O
</s>
<s>
Alternately	O
,	O
toor	B-Operating_System
may	O
be	O
configured	O
with	O
the	O
emergency	O
shell	B-Operating_System
,	O
allowing	O
root	O
the	O
freedom	O
to	O
use	O
the	O
featureful	O
one	O
.	O
</s>
<s>
In	O
a	O
Unix-like	B-Operating_System
system	I-Operating_System
,	O
each	O
user	O
has	O
a	O
user	B-Application
ID	I-Application
number	O
,	O
which	O
is	O
what	O
the	O
kernel	B-Operating_System
uses	O
to	O
distinguish	O
users	O
and	O
to	O
manage	O
user	O
permissions	O
.	O
</s>
<s>
User	B-Application
ID	I-Application
#0	O
is	O
reserved	O
as	O
the	O
superuser	B-Application
account	O
,	O
and	O
is	O
given	O
permission	O
to	O
do	O
anything	O
on	O
the	O
system	O
.	O
</s>
<s>
Users	O
log	O
in	O
by	O
username	O
,	O
not	O
by	O
ID	O
number	O
,	O
and	O
a	O
user	O
's	O
choice	O
of	O
login	O
shell	B-Operating_System
is	O
also	O
managed	O
by	O
name	O
.	O
</s>
<s>
This	O
separation	O
between	O
name	O
and	O
number	O
allows	O
a	O
given	O
user	B-Application
ID	I-Application
to	O
be	O
associated	O
with	O
more	O
than	O
one	O
username	O
,	O
each	O
having	O
its	O
own	O
shell	B-Operating_System
.	O
</s>
<s>
The	O
presence	O
of	O
a	O
'	O
toor	B-Operating_System
 '	O
account	O
(	O
or	O
the	O
presence	O
of	O
more	O
than	O
one	O
account	O
with	O
a	O
user	B-Application
ID	I-Application
of	O
0	O
)	O
triggers	O
a	O
warning	O
in	O
many	O
security	O
auditing	O
systems	O
.	O
</s>
<s>
This	O
is	O
valuable	O
,	O
since	O
if	O
the	O
system	B-Application
administrator	I-Application
did	O
not	O
intend	O
for	O
a	O
second	O
superuser	B-Application
account	O
,	O
then	O
it	O
may	O
mean	O
that	O
the	O
system	O
has	O
been	O
compromised	O
.	O
</s>
<s>
It	O
may	O
be	O
argued	O
that	O
even	O
an	O
intentional	O
'	O
toor	B-Operating_System
 '	O
account	O
is	O
a	O
security	O
risk	O
,	O
since	O
it	O
provides	O
a	O
second	O
point	O
of	O
attack	O
for	O
someone	O
trying	O
to	O
illicitly	O
gain	O
superuser	B-Application
privileges	O
on	O
the	O
system	O
.	O
</s>
<s>
For	O
example	O
,	O
NetBSD	B-Device
ships	O
with	O
a	O
disabled	O
'	O
toor	B-Operating_System
 '	O
account	O
,	O
meaning	O
that	O
there	O
is	O
no	O
password	O
with	O
which	O
one	O
can	O
log	O
into	O
the	O
system	O
as	O
'	O
toor	B-Operating_System
 '	O
.	O
</s>
<s>
However	O
,	O
if	O
the	O
system	O
is	O
compromised	O
,	O
an	O
administrator	O
may	O
be	O
less	O
likely	O
to	O
notice	O
the	O
enabling	O
of	O
a	O
disabled	O
account	O
than	O
the	O
creation	O
of	O
a	O
new	O
one	O
,	O
especially	O
if	O
they	O
have	O
become	O
accustomed	O
to	O
ignoring	O
warnings	O
about	O
'	O
toor	B-Operating_System
 '	O
from	O
their	O
(	O
arguably	O
misconfigured	O
)	O
security	O
program	O
.	O
</s>
