<s>
ZyNOS	B-Operating_System
is	O
the	O
proprietary	O
operating	O
system	O
used	O
on	O
network	O
devices	O
made	O
by	O
Zyxel	O
Communications	O
.	O
</s>
<s>
The	O
name	O
is	O
a	O
contraction	O
of	O
Zyxel	O
and	O
Network	B-Protocol
Operating	I-Protocol
System	I-Protocol
(	O
NOS	O
)	O
.	O
</s>
<s>
Zyxel	O
first	O
introduced	O
ZyNOS	B-Operating_System
in	O
1998	O
.	O
</s>
<s>
Zyxel	O
released	O
ZyNOS	B-Operating_System
version	O
4.0	O
for	O
their	O
GS2200	O
series	O
24	O
and	O
48	O
port	O
ethernet	B-Protocol
switches	I-Protocol
in	O
April	O
,	O
2012	O
.	O
</s>
<s>
Web	O
and/or	O
command-line	B-Application
interface	I-Application
(	O
CLI	O
)	O
depending	O
on	O
the	O
device	O
.	O
</s>
<s>
Web	O
access	O
is	O
accomplished	O
by	O
connecting	O
an	O
Ethernet	O
cable	O
between	O
a	O
PC	O
and	O
an	O
open	O
port	O
on	O
the	O
device	O
and	O
entering	O
the	O
IP	B-Protocol
address	O
of	O
the	O
device	O
into	O
the	O
Web	O
browser	O
.	O
</s>
<s>
An	O
RS-232	O
serial	O
console	O
port	O
is	O
provided	O
on	O
some	O
devices	O
for	O
CLI	O
access	O
,	O
which	O
is	O
accomplished	O
by	O
using	O
SSH	B-Protocol
or	O
telnet	B-Protocol
.	O
</s>
<s>
As	O
of	O
January	O
2014	O
a	O
ZyNOS	B-Operating_System
ROM-0	O
vulnerability	O
has	O
been	O
identified	O
.	O
</s>
<s>
,	O
Danish	O
computer	O
security	O
company	O
Secunia	O
reports	O
no	O
unpatched	O
advisories	O
or	O
vulnerabilities	O
on	O
ZyNOS	B-Operating_System
version	O
4.x	O
.	O
</s>
<s>
,	O
Secunia	O
reports	O
seven	O
advisories	O
and	O
six	O
vulnerabilities	O
on	O
ZyNOS	B-Operating_System
version	O
3.x	O
.	O
</s>
<s>
,	O
a	O
DNS	O
vulnerability	O
has	O
been	O
found	O
in	O
certain	O
ZyNOS	B-Operating_System
firmware	O
versions	O
.	O
</s>
