<s>
NX	B-Application
technology	I-Application
,	O
commonly	O
known	O
as	O
NX	B-Application
or	O
NoMachine	B-Application
,	O
is	O
a	O
proprietary	B-Application
cross-platform	O
software	O
application	O
for	O
remote	O
access	O
,	O
desktop	O
sharing	O
,	O
virtual	O
desktop	O
(	O
on	O
Linux	B-Application
only	O
)	O
and	O
file	O
transfer	O
between	O
computers	O
.	O
</s>
<s>
It	O
is	O
developed	O
by	O
the	O
Luxembourg-based	O
company	O
NoMachine	B-Application
.	O
</s>
<s>
NX	B-Application
's	O
design	O
was	O
derived	O
from	O
the	O
Differential	O
X	B-Operating_System
Protocol	O
Compressor	O
project	O
(	O
DXPC	O
)	O
.	O
</s>
<s>
In	O
2003	O
,	O
the	O
compression	O
and	O
transport	O
protocol	O
NX	B-Application
was	O
created	O
to	O
improve	O
the	O
performance	O
of	O
the	O
native	O
X	B-Operating_System
display	O
protocol	O
so	O
it	O
could	O
be	O
used	O
over	O
slow	O
connections	O
such	O
as	O
dial-up	O
modems	O
.	O
</s>
<s>
It	O
wrapped	O
remote	O
connections	O
in	O
SSH	B-Protocol
sessions	O
for	O
encryption	O
.	O
</s>
<s>
The	O
core	O
compression	O
technology	O
was	O
released	O
under	O
the	O
GNU	O
GPL2	B-License
license	O
(	O
NX	B-Application
1	O
)	O
for	O
Linux	B-Application
servers	O
,	O
whilst	O
other	O
components	O
such	O
as	O
the	O
NX	B-Application
Server	I-Application
and	O
NX	B-Application
Client	I-Application
programs	O
remained	O
proprietary	B-Application
,	O
on	O
February	O
14	O
,	O
2003	O
.	O
</s>
<s>
The	O
last	O
update	O
to	O
this	O
open-source	B-Application
version	O
was	O
released	O
in	O
2012	O
.	O
</s>
<s>
In	O
2010	O
,	O
the	O
company	O
announced	O
they	O
would	O
be	O
releasing	O
the	O
technology	O
under	O
a	O
proprietary	B-Application
license	I-Application
.	O
</s>
<s>
Starting	O
in	O
2013	O
,	O
with	O
the	O
release	O
of	O
version	O
4.0	O
,	O
NX	B-Application
became	O
closed-source	B-Application
.	O
</s>
<s>
It	O
was	O
in	O
2013	O
that	O
NX	B-Application
software	O
became	O
NoMachine	B-Application
software	O
.	O
</s>
<s>
NoMachine	B-Application
NX	I-Application
can	O
be	O
installed	O
on	O
Windows	B-Application
,	O
Mac	B-Application
,	O
Linux	B-Application
,	O
Raspberry	B-Operating_System
Pi	I-Operating_System
and	O
Linux	B-Application
ARM	B-Architecture
computers	O
to	O
let	O
users	O
remotely	O
access	O
the	O
desktop	O
over	O
the	O
network	O
.	O
</s>
<s>
Users	O
connect	O
from	O
a	O
Windows	B-Application
,	O
macOS	B-Application
,	O
iOS	B-Application
,	O
Android	B-Application
,	O
Linux	B-Application
,	O
Raspberry	B-Operating_System
Pi	I-Operating_System
,	O
Linux	B-Application
ARM	B-Architecture
or	O
Web	B-Application
browser	I-Application
.	O
</s>
<s>
Other	O
features	O
include	O
USB	O
redirection	O
,	O
session	O
recording	O
,	O
file	O
transfer	O
,	O
multimedia	O
capability	O
and	O
browser-based	O
access	O
.	O
</s>
<s>
NoMachine	B-Application
Linux	B-Application
products	O
also	O
offer	O
the	O
ability	O
to	O
run	O
multiple	O
virtual	O
Linux	B-Application
desktops	O
on	O
a	O
Linux	B-Application
server	O
(	O
Linux	B-Application
Terminal	B-Device
Server	I-Device
)	O
which	O
are	O
remotely	O
accessed	O
over	O
a	O
network	O
connection	O
.	O
</s>
<s>
NX	B-Application
utilizes	O
uses	O
a	O
combination	O
of	O
video	O
and	O
image	O
encoding	O
based	O
on	O
standard	O
codecs	O
and	O
a	O
number	O
of	O
techniques	O
developed	O
by	O
NoMachine	B-Application
as	O
well	O
as	O
VirtualGL	B-Protocol
to	O
access	O
high-end	O
OpenGL-based	O
X11	B-Operating_System
applications	O
and	O
3D	O
CAD	B-Application
programs	I-Application
.	O
</s>
<s>
NX	B-Application
4	O
introduced	O
optimal	O
image	O
compression	O
and	O
caching	B-General_Concept
with	O
the	O
latest	O
video-encoding	O
techniques	O
.	O
</s>
<s>
When	O
connecting	O
hosts	O
across	O
the	O
network	O
,	O
the	O
NX	B-Application
protocol	O
works	O
as	O
a	O
generic	O
tunnel	O
,	O
with	O
additional	O
framing	O
and	O
flow	O
control	O
information	O
,	O
and	O
dynamically	O
adapts	O
compression	O
and	O
bandwidth	O
according	O
to	O
network	O
speed	O
and	O
capacity	O
.	O
</s>
<s>
Client	O
applications	O
can	O
connect	O
using	O
the	O
SSH	B-Protocol
protocol	O
,	O
with	O
the	O
same	O
authentication	O
mechanisms	O
as	O
version	O
3	O
,	O
by	O
a	O
new	O
SSH	B-Protocol
system	O
login	O
,	O
or	O
by	O
the	O
new	O
SSL-enabled	O
NX	B-Application
daemon	O
.	O
</s>
<s>
Clients	O
can	O
also	O
use	O
one	O
of	O
the	O
various	O
NoMachine	B-Application
subsystems	O
,	O
such	O
as	O
the	O
file	O
synchronization	O
service	O
,	O
software	O
updates	O
,	O
directory	O
services	O
,	O
voice/video	O
messaging	O
and	O
server	O
clustering	O
.	O
</s>
<s>
NX	B-Application
4	O
added	O
new	O
channel	O
types	O
to	O
handle	O
services	O
such	O
as	O
the	O
new	O
file-system	O
redirection	O
,	O
new	O
printing	O
system	O
,	O
virtual	O
network	O
interfaces	O
,	O
smart	O
cards	O
and	O
USB	O
devices	O
.	O
</s>
<s>
Most	O
NoMachine	B-Application
components	O
,	O
including	O
the	O
agent	O
program	O
that	O
impersonates	O
the	O
desktop	O
session	O
on	O
the	O
server	O
,	O
embed	O
so-called	O
"	O
slave	O
servers	O
"	O
—	O
lightweight	O
servers	O
that	O
provide	O
inter-process	O
communication	O
and	O
automation	O
that	O
can	O
be	O
used	O
to	O
create	O
additional	O
channels	O
,	O
under	O
the	O
control	O
of	O
the	O
client	O
and	O
server	O
.	O
</s>
<s>
Applications	O
can	O
still	O
request	O
that	O
channels	O
carry	O
data	O
using	O
the	O
NX	B-Application
X	B-Operating_System
Window	I-Operating_System
System	I-Operating_System
protocol	O
compression	O
.	O
</s>
<s>
Currently	O
,	O
the	O
display	O
(	O
video	O
)	O
channels	O
can	O
handle	O
data	O
in	O
H.264	B-Application
,	O
VP8	B-Algorithm
,	O
MJPEG	B-Application
and	O
other	O
formats	O
,	O
with	O
additional	O
primitives	O
used	O
to	O
implement	O
special	O
encoding	O
operations	O
concurrent	O
with	O
standard	O
audio	O
and	O
video	O
streams	O
.	O
</s>
<s>
Once	O
the	O
session	O
is	O
established	O
between	O
client	O
and	O
server	O
,	O
NX	B-Application
data	O
can	O
travel	O
on	O
TCP	O
and	O
UDP	O
streams	O
.	O
</s>
<s>
UDP	O
communication	O
is	O
disabled	O
when	O
using	O
SSH	B-Protocol
tunneling	O
,	O
so	O
that	O
all	O
data	O
uses	O
the	O
same	O
SSH	B-Protocol
link	O
.	O
</s>
<s>
The	O
display	O
protocol	O
uses	O
a	O
combination	O
of	O
video	O
and	O
image	O
encoding	O
,	O
based	O
on	O
standard	O
codecs	O
and	O
a	O
number	O
of	O
techniques	O
developed	O
by	O
NoMachine	B-Application
.	O
</s>
<s>
NX	B-Application
monitors	O
display	O
and	O
user	O
activity	O
to	O
adapt	O
quality	O
and	O
buffering	O
to	O
the	O
displayed	O
application	O
.	O
</s>
<s>
From	O
version	O
4.0	O
on	O
,	O
when	O
the	O
default	O
NX	B-Application
protocol	O
is	O
used	O
,	O
the	O
login	O
can	O
be	O
via	O
password-based	O
authentication	O
,	O
private	O
key	O
or	O
Kerberos	B-Protocol
ticket	I-Protocol
authentication	O
.	O
</s>
<s>
When	O
NX	B-Application
is	O
configured	O
to	O
send	O
its	O
data	O
by	O
SSH	B-Protocol
(	O
available	O
only	O
on	O
enterprise-version	O
servers	O
)	O
,	O
the	O
following	O
authentication	O
methods	O
are	O
available	O
:	O
</s>
<s>
Login	O
with	O
SSH	B-Protocol
key	I-Protocol
forwarded	O
from	O
client	O
(	O
e.g.	O
</s>
<s>
Login	O
with	O
Kerberos	B-Protocol
ticket	I-Protocol
requested	O
by	O
PAM	B-Application
module	O
on	O
server	O
host	O
.	O
</s>
<s>
NX	B-Application
compresses	B-General_Concept
the	O
X11	B-Operating_System
data	O
to	O
minimize	O
the	O
amount	O
of	O
data	O
transmitted	O
,	O
and	O
caches	B-General_Concept
data	O
to	O
keep	O
the	O
session	O
as	O
responsive	O
as	O
possible	O
.	O
</s>
<s>
NX	B-Application
is	O
faster	O
than	O
its	O
predecessors	O
,	O
as	O
it	O
eliminates	O
most	O
of	O
the	O
X	B-Operating_System
round	O
trips	O
,	O
while	O
dxpc	O
and	O
MLView	O
only	O
compress	O
data	O
.	O
</s>
<s>
The	O
two	O
principal	O
components	O
of	O
NX	B-Application
are	O
nxproxy	O
and	O
nxagent	O
.	O
</s>
<s>
nxproxy	O
is	O
derived	O
from	O
dxpc	O
and	O
is	O
started	O
on	O
both	O
the	O
remote	O
(	O
client	O
in	O
X	B-Operating_System
terminology	O
)	O
and	O
local	O
(	O
server	O
in	O
X	B-Operating_System
terminology	O
)	O
machines	O
,	O
simulating	O
an	O
X	B-Operating_System
server	O
on	O
the	O
client	O
and	O
forwarding	O
remote	O
X	B-Operating_System
protocol	O
requests	O
to	O
the	O
local	O
X	B-Operating_System
server	O
.	O
</s>
<s>
nxproxy	O
alone	O
achieves	O
1:10	O
to	O
1:1000	O
compression	O
ratios	O
,	O
reducing	O
bandwidth	O
,	O
but	O
does	O
not	O
eliminate	O
most	O
of	O
X	B-Operating_System
's	O
synchronous	O
round	O
trips	O
,	O
responsible	O
for	O
most	O
of	O
X	B-Operating_System
's	O
perceived	O
latency	O
.	O
</s>
<s>
nxagent	O
,	O
derived	O
from	O
Xnest	O
(	O
similar	O
to	O
Xephyr	B-Device
)	O
,	O
is	O
typically	O
started	O
on	O
the	O
remote	O
(	O
client	O
)	O
machine	O
,	O
thus	O
avoiding	O
most	O
X11	B-Operating_System
protocol	O
round	O
trips	O
.	O
</s>
<s>
On	O
systems	O
with	O
a	O
functional	O
X11	B-Operating_System
implementation	O
,	O
nxproxy	O
and	O
nxagent	O
are	O
all	O
that	O
is	O
needed	O
to	O
establish	O
a	O
connection	O
with	O
low-bandwidth	O
requirements	O
between	O
a	O
set	O
of	O
remote	O
X	B-Operating_System
clients	O
and	O
the	O
local	O
X	B-Operating_System
server	O
.	O
</s>
<s>
SSH	B-Protocol
can	O
be	O
used	O
to	O
establish	O
a	O
secure	O
tunnel	O
between	O
the	O
hosts	O
.	O
</s>
<s>
NX	B-Application
3	O
relies	O
on	O
SSH	B-Protocol
functionalities	O
and	O
existing	O
open-source	B-Application
SSH	B-Protocol
software	O
,	O
making	O
it	O
possible	O
to	O
run	O
contemporary	O
Unix	O
and	O
Windows	B-Application
desktops	O
and	O
arbitrary	O
network	O
applications	O
over	O
the	O
Internet	O
in	O
a	O
secured	O
and	O
controlled	O
way	O
.	O
</s>
<s>
FreeNX	B-Application
and	O
the	O
various	O
NX	B-Application
Clients	I-Application
are	O
used	O
for	O
setup	O
,	O
handling	O
suspend	O
and	O
resume	O
,	O
secure	O
tunnelling	O
over	O
SSH	B-Protocol
,	O
and	O
printing	O
and	O
sound	O
.	O
</s>
<s>
NoMachine	B-Application
's	O
NX	B-Application
protocol	O
allow	O
client	O
connections	O
to	O
hosts	O
via	O
Remote	B-Protocol
Desktop	I-Protocol
Protocol	I-Protocol
(	O
for	O
Windows	B-Protocol
Remote	I-Protocol
Desktop	I-Protocol
Services	O
sessions	O
)	O
and	O
remote	O
Virtual	B-Protocol
Network	I-Protocol
Computing	I-Protocol
sessions	O
(	O
most	O
modern	O
general-purpose	O
operating	O
system	O
platforms	O
)	O
,	O
as	O
well	O
as	O
XDM	O
.	O
</s>
<s>
Prior	O
to	O
version	O
4.0	O
,	O
NoMachine	B-Application
released	O
core	O
NX	B-Application
technology	I-Application
under	O
the	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
,	O
and	O
offered	O
non-free	B-Application
commercial	O
NX	B-Application
solutions	O
,	O
free	O
client	O
and	O
server	O
products	O
for	O
Linux	B-Application
and	O
Solaris	B-Application
,	O
and	O
free	O
client	O
software	O
for	O
Microsoft	B-Application
Windows	I-Application
,	O
macOS	B-Application
and	O
embedded	B-Architecture
systems	I-Architecture
.	O
</s>
<s>
Due	O
to	O
the	O
free-software	O
nature	O
of	O
older	O
NX	B-Application
releases	O
,	O
the	O
FreeNX	B-Application
project	O
was	O
started	O
to	O
provide	O
wrapper	O
scripts	O
for	O
the	O
GPL	B-License
NX	B-Application
libraries	O
.	O
</s>
<s>
FreeNX	B-Application
was	O
developed	O
and	O
maintained	O
by	O
Fabian	O
Franz	O
,	O
but	O
has	O
not	O
announced	O
a	O
release	O
since	O
2008	O
.	O
</s>
<s>
2X	B-Protocol
Software	I-Protocol
has	O
developed	O
another	O
commercial	O
terminal	B-Device
server	I-Device
for	O
Linux	B-Application
using	O
the	O
NX	B-Application
protocol	O
.	O
</s>
<s>
On	O
July	O
7	O
,	O
2009	O
,	O
Google	B-Application
announced	O
their	O
open-source	B-Application
NX	B-Application
server	I-Application
,	O
Neatx	B-Application
,	O
as	O
an	O
internal	O
project	O
.	O
</s>
<s>
Its	O
source	O
code	O
is	O
available	O
under	O
the	O
GNU	B-License
GPL	I-License
v2	O
license	O
.	O
</s>
<s>
X2Go	B-Application
is	O
based	O
on	O
the	O
3.x	O
NX	B-Application
libraries	O
,	O
but	O
is	O
not	O
compatible	O
with	O
other	O
implementations	O
.	O
</s>
<s>
The	O
primary	O
NX	B-Application
clients	I-Application
are	O
the	O
official	O
freeware	B-License
,	O
NoMachine	B-Application
,	O
and	O
NoMachine	B-Application
Enterprise	O
Client	O
.	O
</s>
<s>
Several	O
open-source	B-Application
projects	O
can	O
also	O
use	O
the	O
NX	B-Application
protocol	O
but	O
many	O
of	O
these	O
OSS	O
projects	O
do	O
not	O
work	O
with	O
more	O
recent	O
versions	O
of	O
the	O
official	O
NX	B-Application
software	O
.	O
</s>
<s>
The	O
kNX	O
project	O
was	O
a	O
proof-of-concept	O
application	O
written	O
by	O
Joseph	O
Wenninger	O
,	O
with	O
plans	O
for	O
it	O
to	O
eventually	O
become	O
a	O
complete	O
NX	B-Application
client	I-Application
to	O
show	O
that	O
an	O
open-source	B-Application
client	O
could	O
be	O
written	O
.	O
</s>
<s>
More	O
recent	O
open-source	B-Application
efforts	O
include	O
QtNX	B-Application
,	O
which	O
offers	O
full	O
suspend	O
and	O
resume	O
.	O
</s>
<s>
However	O
,	O
it	O
has	O
been	O
reported	O
as	O
incompatible	O
with	O
the	O
most	O
recent	O
NX	B-Application
libraries	O
.	O
</s>
<s>
Nxcl	O
,	O
an	O
update	O
to	O
nxclientlib	O
,	O
the	O
core	O
of	O
QtNX	B-Application
,	O
was	O
completed	O
by	O
Seb	O
James	O
in	O
September	O
2007	O
,	O
and	O
works	O
with	O
version	O
3	O
of	O
the	O
NX	B-Application
core	O
libraries	O
.	O
</s>
<s>
It	O
also	O
drops	O
dependency	O
on	O
Qt	O
,	O
which	O
prevented	O
nxclientlib	O
from	O
becoming	O
widely	O
used	O
as	O
a	O
cross-platform	O
basis	O
for	O
NX	B-Application
client	I-Application
programs	O
.	O
</s>
<s>
nxcl	O
provides	O
a	O
library	O
that	O
can	O
be	O
linked	O
to	O
a	O
client	O
program	O
(	O
libnxcl	O
)	O
,	O
and	O
a	O
self-contained	O
NX	B-Application
client	I-Application
with	O
a	O
D-Bus	B-Language
API	B-General_Concept
(	O
the	O
nxcl	O
binary	O
)	O
.	O
</s>
<s>
It	O
is	O
available	O
from	O
the	O
FreeNX	B-Application
Subversion	B-Application
server	O
.	O
</s>
<s>
Another	O
obsolete	O
(	O
last	O
updated	O
Jan	O
2013	O
)	O
OSS	O
NX	B-Application
client	I-Application
is	O
OpenNX	O
,	O
described	O
as	O
a	O
"	O
drop-in	O
replacement	O
for	O
NoMachine	B-Application
's	O
 [ proprietary ] 	O
nxclient	O
"	O
with	O
full	O
suspend	O
and	O
resume	O
.	O
</s>
<s>
Various	O
open-source	B-Application
terminal	B-Device
server	I-Device
projects	O
,	O
such	O
as	O
X2Go	B-Application
,	O
also	O
use	O
the	O
NX	B-Application
protocol	O
.	O
</s>
<s>
However	O
,	O
X2Go	B-Application
is	O
not	O
compatible	O
with	O
other	O
NX	B-Application
servers	I-Application
or	O
clients	O
.	O
</s>
<s>
Remmina	B-Language
,	O
another	O
recent	O
GTK+	O
remote	B-Protocol
desktop	I-Protocol
client	O
project	O
,	O
announced	O
the	O
ability	O
to	O
use	O
the	O
NX	B-Application
protocol	O
in	O
its	O
release	O
0.8	O
.	O
</s>
