<s>
The	O
TUX	B-Application
web	I-Application
server	I-Application
is	O
an	O
unmaintained	O
in-kernel	B-Protocol
web	I-Protocol
server	I-Protocol
for	O
Linux	B-Operating_System
licensed	O
under	O
the	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
(	O
GPL	B-License
)	O
.	O
</s>
<s>
It	O
was	O
limited	O
to	O
serving	O
static	O
web	O
pages	O
and	O
coordinating	O
between	O
kernelspace	B-Operating_System
modules	B-Application
,	O
userspace	B-Operating_System
modules	B-Application
,	O
and	O
regular	O
userspace	B-Operating_System
web	B-Application
server	I-Application
daemons	B-Operating_System
that	O
provide	O
dynamic	O
content	O
.	O
</s>
<s>
Regular	O
userspace	B-Operating_System
web	B-Application
servers	I-Application
do	O
not	O
need	O
to	O
be	O
altered	O
in	O
any	O
way	O
for	O
TUX	O
to	O
coordinate	O
with	O
them	O
.	O
</s>
<s>
However	O
,	O
userspace	B-Operating_System
code	O
has	O
to	O
use	O
a	O
new	O
interface	O
based	O
on	O
the	O
tux(2 )	O
system	O
call	O
.	O
</s>
<s>
The	O
main	O
differences	O
between	O
TUX	O
and	O
other	O
webservers	B-Application
include	O
:	O
</s>
<s>
TUX	O
runs	O
partly	O
within	O
a	O
customized	O
version	O
of	O
the	O
Linux	B-Operating_System
kernel	I-Operating_System
and	O
partly	O
as	O
a	O
userspace	B-Operating_System
daemon	B-Operating_System
.	O
</s>
<s>
With	O
a	O
capable	O
network	B-Protocol
card	I-Protocol
,	O
TUX	O
enables	O
scatter-gather	B-General_Concept
DMA	B-General_Concept
from	O
the	O
page	O
cache	O
directly	O
to	O
the	O
network	O
.	O
</s>
<s>
While	O
only	O
being	O
able	O
to	O
serve	O
static	O
web	O
pages	O
could	O
be	O
seen	O
as	O
a	O
significant	O
disadvantage	O
,	O
TUX	O
has	O
one	O
significant	O
advantage	O
:	O
it	O
is	O
able	O
to	O
serve	O
pages	O
faster	O
than	O
traditional	O
web	B-Application
servers	I-Application
.	O
</s>
<s>
This	O
is	O
largely	O
due	O
to	O
its	O
place	O
directly	O
within	O
the	O
kernel	B-Operating_System
,	O
where	O
it	O
can	O
improve	O
performance	O
by	O
taking	O
advantage	O
of	O
facilities	O
not	O
available	O
to	O
traditional	O
web	B-Application
servers	I-Application
,	O
which	O
run	O
outside	O
of	O
the	O
kernel	B-Operating_System
.	O
</s>
<s>
Because	O
it	O
is	O
running	O
within	O
the	O
kernel	B-Operating_System
,	O
such	O
dynamic	O
content	O
cannot	O
take	O
advantage	O
of	O
functions	O
that	O
the	O
kernel	B-Operating_System
provides	O
to	O
userspace	B-Operating_System
programs	O
,	O
and	O
would	O
create	O
tremendous	O
security	O
issues	O
.	O
</s>
<s>
TUX	O
is	O
capable	O
of	O
launching	O
CGI	B-Language
programs	O
to	O
provide	O
dynamic	O
content	O
.	O
</s>
<s>
However	O
,	O
CGI	B-Language
suffers	O
from	O
significant	O
performance	O
limitations	O
,	O
so	O
a	O
CGI-heavy	O
site	O
would	O
gain	O
no	O
performance	O
advantage	O
from	O
using	O
TUX	O
.	O
</s>
<s>
TUX	O
can	O
also	O
redirect	O
any	O
request	O
it	O
cannot	O
process	O
to	O
a	O
traditional	O
userspace	B-Operating_System
web	B-Application
server	I-Application
daemon	B-Operating_System
,	O
for	O
example	O
Apache	B-Application
or	O
lighttpd	B-Protocol
.	O
</s>
<s>
TUX	O
has	O
never	O
been	O
an	O
integrated	O
part	O
of	O
the	O
official	O
Linux	B-Operating_System
kernel	I-Operating_System
,	O
although	O
it	O
was	O
shipped	O
in	O
some	O
distributions	O
,	O
notably	O
Red	O
Hat	O
,	O
SuSE	O
and	O
Fedora	O
.	O
</s>
<s>
One	O
major	O
component	O
was	O
the	O
Native	B-Application
POSIX	I-Application
Thread	I-Application
Library	I-Application
,	O
which	O
,	O
with	O
the	O
right	O
tuning	O
parameters	O
,	O
allows	O
userspace	B-Operating_System
web	B-Application
servers	I-Application
to	O
serve	O
web	O
pages	O
at	O
a	O
speed	O
very	O
close	O
to	O
that	O
of	O
a	O
kernelspace	B-Protocol
web	I-Protocol
server	I-Protocol
like	O
TUX	O
but	O
without	O
its	O
limitations	O
.	O
</s>
<s>
Core	O
kernel	B-Operating_System
developers	O
also	O
argued	O
that	O
having	O
an	O
HTTP	B-Application
daemon	I-Application
within	O
the	O
kernel	B-Operating_System
is	O
dangerous	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
common	O
bug	O
such	O
as	O
a	O
buffer	B-General_Concept
overflow	I-General_Concept
within	O
TUX	O
could	O
give	O
an	O
attacker	O
superuser	B-Application
control	O
over	O
the	O
machine	O
.	O
</s>
<s>
Therefore	O
,	O
it	O
is	O
much	O
safer	O
to	O
keep	O
the	O
HTTP	B-Application
daemon	I-Application
entirely	O
within	O
userspace	B-Operating_System
,	O
where	O
a	O
bug	O
does	O
not	O
necessarily	O
give	O
an	O
attacker	O
total	O
control	O
.	O
</s>
<s>
Tux	O
has	O
been	O
found	O
to	O
be	O
largely	O
unnecessary	O
as	O
modern	O
kernels	B-Operating_System
and	O
web	B-Application
servers	I-Application
can	O
supply	O
similar	O
speed	O
advantages	O
as	O
Tux	O
did	O
,	O
without	O
the	O
in-kernel	O
downsides	O
.	O
</s>
<s>
There	O
are	O
other	O
options	O
for	O
high-performance	O
static	O
web	B-Application
servers	I-Application
in	O
Linux	B-Operating_System
.	O
</s>
<s>
Nginx	B-Operating_System
found	O
its	O
path	O
to	O
popularity	O
in	O
party	O
by	O
extremely	O
fast	O
serving	O
of	O
static	O
content	O
.	O
</s>
