<s>
Systrace	B-Application
is	O
a	O
computer	O
security	O
utility	O
which	O
limits	O
an	O
application	B-Application
's	I-Application
access	O
to	O
the	O
system	O
by	O
enforcing	O
access	O
policies	O
for	O
system	B-Operating_System
calls	I-Operating_System
.	O
</s>
<s>
This	O
can	O
mitigate	O
the	O
effects	O
of	O
buffer	B-General_Concept
overflows	I-General_Concept
and	O
other	O
security	O
vulnerabilities	O
.	O
</s>
<s>
It	O
was	O
developed	O
by	O
Niels	O
Provos	O
and	O
runs	O
on	O
various	O
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
.	O
</s>
<s>
Systrace	B-Application
is	O
particularly	O
useful	O
when	O
running	O
untrusted	O
or	O
binary-only	O
applications	O
and	O
provides	O
facilities	O
for	O
privilege	O
elevation	O
on	O
a	O
system	B-Operating_System
call	I-Operating_System
basis	O
,	O
helping	O
to	O
eliminate	O
the	O
need	O
for	O
potentially	O
dangerous	O
setuid	O
programs	O
.	O
</s>
<s>
Systrace	B-Application
used	O
to	O
be	O
integrated	O
into	O
OpenBSD	B-Operating_System
,	O
but	O
was	O
removed	O
in	O
April	O
2016	O
(	O
in	O
favour	O
of	O
pledge	O
post	O
OpenBSD	B-Operating_System
5.9	O
)	O
.	O
</s>
<s>
It	O
is	O
available	O
for	O
Linux	B-Application
and	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
,	O
although	O
the	O
OS	B-Operating_System
X	I-Operating_System
port	O
is	O
currently	O
unmaintained	O
.	O
</s>
<s>
It	O
was	O
removed	O
from	O
NetBSD	B-Device
at	O
the	O
end	O
of	O
2007	O
due	O
to	O
several	O
unfixed	O
implementation	O
issues	O
.	O
</s>
<s>
As	O
of	O
version	O
1.6f	O
Systrace	B-Application
supports	O
64-bit	O
Linux	B-Application
2.6.1	O
via	O
kernel	O
patch	O
.	O
</s>
<s>
Systrace	B-Application
supports	O
the	O
following	O
features	O
:	O
</s>
<s>
Confines	O
untrusted	O
binary	O
applications	O
:	O
An	O
application	O
is	O
allowed	O
to	O
make	O
only	O
those	O
system	B-Operating_System
calls	I-Operating_System
specified	O
as	O
permitted	O
in	O
the	O
policy	O
.	O
</s>
<s>
If	O
the	O
application	O
attempts	O
to	O
execute	O
a	O
system	B-Operating_System
call	I-Operating_System
that	O
is	O
not	O
explicitly	O
permitted	O
,	O
an	O
alarm	O
gets	O
raised	O
.	O
</s>
<s>
Interactive	O
policy	O
generation	O
with	O
graphical	O
user	O
interface	O
:	O
Policies	O
can	O
be	O
generated	O
interactively	O
via	O
a	O
graphical	O
frontend	O
to	O
Systrace	B-Application
.	O
</s>
<s>
The	O
frontend	O
shows	O
system	B-Operating_System
calls	I-Operating_System
and	O
their	O
parameters	O
not	O
currently	O
covered	O
by	O
policy	O
and	O
allows	O
the	O
user	O
to	O
refine	O
the	O
policy	O
until	O
it	O
works	O
as	O
expected	O
.	O
</s>
<s>
Supports	O
different	O
emulations	O
:	O
Linux	B-Application
,	O
BSDI	O
,	O
etc	O
..	O
</s>
<s>
Non-interactive	O
policy	O
enforcement	O
:	O
Once	O
a	O
policy	O
has	O
been	O
trained	O
,	O
automatic	O
policy	O
enforcement	O
can	O
be	O
used	O
to	O
deny	O
all	O
system	B-Operating_System
calls	I-Operating_System
not	O
covered	O
by	O
the	O
current	O
policy	O
.	O
</s>
<s>
Remote	O
monitoring	O
and	O
intrusion	O
detection	O
:	O
Systrace	B-Application
supports	O
multiple	O
frontends	O
by	O
using	O
a	O
frontend	O
that	O
makes	O
use	O
of	O
the	O
network	O
,	O
very	O
advanced	O
features	O
are	O
possible	O
.	O
</s>
<s>
Privilege	O
elevation	O
:	O
Using	O
Systrace	B-Application
's	O
privilege	O
elevation	O
mode	O
,	O
it	O
's	O
possible	O
to	O
get	O
rid	O
of	O
setuid	O
binaries	O
.	O
</s>
<s>
A	O
special	O
policy	O
statement	O
allows	O
selected	O
system	B-Operating_System
calls	I-Operating_System
to	O
run	O
with	O
higher	O
privileges	O
,	O
for	O
example	O
,	O
creating	O
a	O
raw	B-Protocol
socket	I-Protocol
.	O
</s>
<s>
Systrace	B-Application
has	O
had	O
some	O
vulnerabilities	O
in	O
the	O
past	O
,	O
including	O
:	O
</s>
