<s>
The	O
Simple	O
Service	O
Discovery	O
Protocol	O
(	O
SSDP	O
)	O
is	O
a	O
network	O
protocol	O
based	O
on	O
the	O
Internet	B-Protocol
protocol	I-Protocol
suite	I-Protocol
for	O
advertisement	O
and	O
discovery	O
of	O
network	O
services	O
and	O
presence	O
information	O
.	O
</s>
<s>
It	O
accomplishes	O
this	O
without	O
assistance	O
of	O
server-based	O
configuration	O
mechanisms	O
,	O
such	O
as	O
Dynamic	B-Protocol
Host	I-Protocol
Configuration	I-Protocol
Protocol	I-Protocol
(	O
DHCP	B-Protocol
)	O
or	O
Domain	B-Protocol
Name	I-Protocol
System	I-Protocol
(	O
DNS	B-Protocol
)	O
,	O
and	O
without	O
special	O
static	O
configuration	O
of	O
a	O
network	O
host	O
.	O
</s>
<s>
SSDP	O
is	O
the	O
basis	O
of	O
the	O
discovery	O
protocol	O
of	O
Universal	B-Application
Plug	I-Application
and	I-Application
Play	I-Application
(	O
UPnP	B-Application
)	O
and	O
is	O
intended	O
for	O
use	O
in	O
residential	O
or	O
small	O
office	O
environments	O
.	O
</s>
<s>
Although	O
the	O
IETF	O
proposal	O
has	O
since	O
expired	O
(	O
April	O
,	O
2000	O
)	O
,	O
SSDP	O
was	O
incorporated	O
into	O
the	O
UPnP	B-Application
protocol	O
stack	O
,	O
and	O
a	O
description	O
of	O
the	O
final	O
implementation	O
is	O
included	O
in	O
UPnP	B-Application
standards	O
documents	O
.	O
</s>
<s>
SSDP	O
is	O
a	O
text-based	O
protocol	O
based	O
on	O
HTTPU	O
,	O
which	O
uses	O
UDP	B-Protocol
as	O
the	O
underlying	O
transport	O
protocol	O
.	O
</s>
<s>
Services	O
are	O
announced	O
by	O
the	O
hosting	O
system	O
with	O
multicast	O
addressing	O
to	O
a	O
specifically	O
designated	O
IP	B-Protocol
multicast	I-Protocol
address	O
at	O
UDP	B-Protocol
port	I-Protocol
number	O
1900	O
.	O
</s>
<s>
In	O
IPv4	B-Protocol
,	O
the	O
multicast	O
address	O
is	O
and	O
SSDP	O
over	O
IPv6	B-Protocol
uses	O
the	O
address	O
set	O
for	O
all	O
scope	O
ranges	O
indicated	O
by	O
.	O
</s>
<s>
Additionally	O
,	O
applications	O
may	O
use	O
the	O
source-specific	O
multicast	O
addresses	O
derived	O
from	O
the	O
local	O
IPv6	B-Protocol
routing	O
prefix	O
,	O
with	O
group	O
ID	O
C	O
(	O
decimal	O
12	O
)	O
.	O
</s>
<s>
Responses	O
to	O
such	O
search	O
requests	O
are	O
sent	O
via	O
unicast	O
addressing	O
to	O
the	O
originating	O
address	O
and	O
port	B-Protocol
number	I-Protocol
of	O
the	O
multicast	O
request	O
.	O
</s>
<s>
Microsoft	O
's	O
IPv6	B-Protocol
SSDP	O
implementations	O
in	O
Windows	O
Media	O
Player	O
and	O
Server	O
use	O
the	O
link-local	B-Protocol
scope	O
address	O
.	O
</s>
<s>
Microsoft	O
uses	O
port	B-Protocol
number	I-Protocol
2869	O
for	O
event	O
notification	O
and	O
event	O
subscriptions	O
.	O
</s>
<s>
Many	O
devices	O
,	O
including	O
some	O
residential	O
routers	O
,	O
have	O
a	O
vulnerability	O
in	O
the	O
UPnP	B-Application
software	O
that	O
allows	O
an	O
attacker	O
to	O
get	O
replies	O
from	O
port	B-Protocol
number	I-Protocol
1900	I-Protocol
to	O
a	O
destination	O
address	O
of	O
their	O
choice	O
.	O
</s>
<s>
With	O
a	O
botnet	B-Architecture
of	O
thousands	O
of	O
devices	O
,	O
the	O
attackers	O
can	O
generate	O
sufficient	O
packet	O
rates	O
and	O
occupy	O
bandwidth	O
to	O
saturate	O
links	O
,	O
causing	O
the	O
denial	O
of	O
services	O
.	O
</s>
<s>
The	O
network	O
company	O
Cloudflare	B-Application
has	O
described	O
this	O
attack	O
as	O
the	O
"	O
Stupidly	O
Simple	O
DDoS	O
Protocol	O
"	O
.	O
</s>
