<s>
PuTTY	B-Operating_System
(	O
)	O
is	O
a	O
free	B-License
and	I-License
open-source	I-License
terminal	B-Application
emulator	I-Application
,	O
serial	B-Device
console	I-Device
and	O
network	O
file	O
transfer	O
application	O
.	O
</s>
<s>
It	O
supports	O
several	O
network	O
protocols	O
,	O
including	O
SCP	B-Protocol
,	O
SSH	B-Protocol
,	O
Telnet	B-Protocol
,	O
rlogin	B-Application
,	O
and	O
raw	O
socket	O
connection	O
.	O
</s>
<s>
It	O
can	O
also	O
connect	O
to	O
a	O
serial	B-Protocol
port	I-Protocol
.	O
</s>
<s>
The	O
name	O
"	O
PuTTY	B-Operating_System
"	O
has	O
no	O
official	O
meaning	O
.	O
</s>
<s>
PuTTY	B-Operating_System
was	O
originally	O
written	O
for	O
Microsoft	B-Application
Windows	I-Application
,	O
but	O
it	O
has	O
been	O
ported	O
to	O
various	O
other	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
Official	O
ports	O
are	O
available	O
for	O
some	O
Unix-like	B-Operating_System
platforms	O
,	O
with	O
work-in-progress	O
ports	O
to	O
and	O
,	O
and	O
unofficial	O
ports	O
have	O
been	O
contributed	O
to	O
platforms	O
such	O
as	O
Symbian	B-Operating_System
,	O
Windows	B-Operating_System
Mobile	I-Operating_System
and	O
Windows	B-Protocol
Phone	I-Protocol
.	O
</s>
<s>
PuTTY	B-Operating_System
was	O
written	O
and	O
is	O
maintained	O
primarily	O
by	O
Simon	O
Tatham	O
,	O
a	O
British	O
programmer	O
.	O
</s>
<s>
PuTTY	B-Operating_System
supports	O
many	O
variations	O
on	O
the	O
secure	O
remote	O
terminal	O
,	O
and	O
provides	O
user	O
control	O
over	O
the	O
SSH	B-Protocol
encryption	O
key	O
and	O
protocol	O
version	O
,	O
alternate	O
ciphers	O
such	O
as	O
AES	B-Algorithm
,	O
3DES	B-Algorithm
,	O
RC4	B-Algorithm
,	O
Blowfish	B-Algorithm
,	O
DES	B-Algorithm
,	O
and	O
Public-key	B-Application
authentication	O
.	O
</s>
<s>
PuTTY	B-Operating_System
uses	O
its	O
own	O
format	O
of	O
key	O
files	O
–	O
PPK	O
(	O
protected	O
by	O
Message	O
Authentication	O
Code	O
)	O
.	O
</s>
<s>
PuTTY	B-Operating_System
supports	O
SSO	O
through	O
GSSAPI	O
,	O
including	O
user	O
provided	O
GSSAPI	O
DLLs	O
.	O
</s>
<s>
It	O
also	O
can	O
emulate	O
control	O
sequences	O
from	O
xterm	B-Language
,	O
VT220	B-Device
,	O
VT102	O
or	O
ECMA-48	O
terminal	B-Application
emulation	I-Application
,	O
and	O
allows	O
local	O
,	O
remote	O
,	O
or	O
dynamic	O
port	B-Protocol
forwarding	I-Protocol
with	O
SSH	B-Protocol
(	O
including	O
X11	B-Operating_System
forwarding	O
)	O
.	O
</s>
<s>
The	O
network	O
communication	O
layer	O
supports	O
IPv6	B-Protocol
,	O
and	O
the	O
SSH	B-Protocol
protocol	O
supports	O
the	O
zlib@openssh.com	O
delayed	O
compression	O
scheme	O
.	O
</s>
<s>
It	O
can	O
also	O
be	O
used	O
with	O
local	O
serial	B-Protocol
port	I-Protocol
connections	O
.	O
</s>
<s>
PuTTY	B-Operating_System
comes	O
bundled	O
with	O
command-line	O
SCP	B-Protocol
and	O
SFTP	B-Protocol
clients	O
,	O
called	O
"	O
pscp	B-Operating_System
"	O
and	O
"	O
psftp	B-Operating_System
"	O
respectively	O
,	O
and	O
plink	O
,	O
a	O
command-line	O
connection	O
tool	O
,	O
used	O
for	O
non-interactive	O
sessions	O
.	O
</s>
<s>
PuTTY	B-Operating_System
does	O
not	O
support	O
session	O
tabs	O
directly	O
,	O
but	O
many	O
wrappers	O
are	O
available	O
that	O
do	O
.	O
</s>
<s>
PuTTY	B-Operating_System
development	O
began	O
late	O
in	O
1998	O
,	O
and	O
was	O
a	O
usable	O
SSH-2	O
client	O
by	O
October	O
2000	O
.	O
</s>
<s>
PuTTY	B-Operating_System
consists	O
of	O
several	O
components	O
:	O
</s>
<s>
PSCP	B-Operating_System
an	O
SCP	B-Protocol
client	O
,	O
i.e.	O
</s>
<s>
PSFTP	B-Operating_System
an	O
SFTP	B-Protocol
client	O
,	O
i.e.	O
</s>
<s>
Plink	O
a	O
command-line	O
interface	O
to	O
the	O
PuTTY	B-Operating_System
back	O
ends	O
.	O
</s>
