<s>
Reverse	B-Protocol
telnet	I-Protocol
is	O
a	O
specialized	O
application	O
of	O
telnet	B-Protocol
,	O
where	O
the	O
server	O
side	O
of	O
the	O
connection	O
reads	O
and	O
writes	O
data	O
to	O
a	O
computer	B-General_Concept
terminal	I-General_Concept
line	O
(	O
RS-232	O
serial	B-Protocol
port	I-Protocol
)	O
,	O
rather	O
than	O
providing	O
a	O
command	O
shell	O
to	O
the	O
host	O
device	O
.	O
</s>
<s>
Typically	O
,	O
reverse	B-Protocol
telnet	I-Protocol
is	O
implemented	O
on	O
an	O
embedded	O
device	O
(	O
e.g.	O
</s>
<s>
Through	O
the	O
use	O
of	O
reverse	B-Protocol
telnet	I-Protocol
on	O
such	O
a	O
device	O
,	O
IP-networked	O
users	O
can	O
use	O
telnet	B-Protocol
to	O
access	O
serially-connected	O
devices	O
.	O
</s>
<s>
In	O
the	O
past	O
,	O
reverse	B-Protocol
telnet	I-Protocol
was	O
typically	O
used	O
to	O
connect	O
to	O
modems	B-Application
or	O
other	O
external	O
asynchronous	O
devices	O
.	O
</s>
<s>
Today	O
,	O
reverse	B-Protocol
telnet	I-Protocol
is	O
used	O
mostly	O
for	O
connecting	O
to	O
the	O
console	B-Protocol
port	I-Protocol
of	O
a	O
router	O
,	O
a	O
switch	O
or	O
other	O
device	O
.	O
</s>
<s>
On	O
the	O
client	O
,	O
the	O
command	O
line	O
for	O
initiating	O
a	O
"	O
reverse	B-Protocol
telnet	I-Protocol
"	O
connection	O
might	O
look	O
like	O
this	O
:	O
</s>
<s>
(	O
The	O
syntax	O
in	O
the	O
above	O
example	O
would	O
be	O
valid	O
for	O
the	O
command-line	O
telnet	B-Protocol
client	O
packaged	O
with	O
many	O
operating	O
systems	O
,	O
including	O
most	O
Unix	B-Application
operating	I-Application
systems	I-Application
,	O
or	O
available	O
as	O
an	O
option	O
or	O
add-on	O
.	O
)	O
</s>
<s>
In	O
this	O
example	O
,	O
172.16.1.254	O
is	O
the	O
IP	B-Protocol
address	I-Protocol
of	O
the	O
console	O
device	O
,	O
and	O
2002	O
is	O
the	O
TCP	B-Protocol
port	I-Protocol
associated	O
with	O
a	O
terminal	O
line	O
on	O
the	O
server	O
.	O
</s>
