<s>
An	O
ephemeral	B-Protocol
port	I-Protocol
is	O
a	O
communications	O
endpoint	O
(	O
port	B-Protocol
)	O
of	O
a	O
transport	B-Architecture
layer	I-Architecture
protocol	O
of	O
the	O
Internet	B-Protocol
protocol	I-Protocol
suite	I-Protocol
that	O
is	O
used	O
for	O
only	O
a	O
short	O
period	O
of	O
time	O
for	O
the	O
duration	O
of	O
a	O
communication	O
session	O
.	O
</s>
<s>
Such	O
short-lived	O
ports	O
are	O
allocated	O
automatically	O
within	O
a	O
predefined	O
range	O
of	O
port	B-Protocol
numbers	I-Protocol
by	O
the	O
IP	B-Protocol
stack	I-Protocol
software	O
of	O
a	O
computer	O
operating	O
system	O
.	O
</s>
<s>
The	O
Transmission	B-Protocol
Control	I-Protocol
Protocol	I-Protocol
(	O
TCP	O
)	O
,	O
the	O
User	B-Protocol
Datagram	I-Protocol
Protocol	I-Protocol
(	O
UDP	O
)	O
,	O
and	O
the	O
Stream	B-Protocol
Control	I-Protocol
Transmission	I-Protocol
Protocol	I-Protocol
(	O
SCTP	B-Protocol
)	O
typically	O
use	O
an	O
ephemeral	B-Protocol
port	I-Protocol
for	O
the	O
client-end	O
of	O
a	O
client	B-Operating_System
–	I-Operating_System
server	I-Operating_System
communication	O
.	O
</s>
<s>
At	O
the	O
server	B-Application
end	O
of	O
the	O
communication	O
session	O
,	O
ephemeral	B-Protocol
ports	I-Protocol
may	O
also	O
be	O
used	O
for	O
continuation	O
of	O
communications	O
with	O
a	O
client	B-Protocol
that	O
initially	O
connected	O
to	O
one	O
of	O
the	O
services	O
listening	O
with	O
a	O
well-known	O
port	B-Protocol
.	O
</s>
<s>
For	O
example	O
,	O
the	O
Trivial	B-Device
File	I-Device
Transfer	I-Device
Protocol	I-Device
(	O
TFTP	B-Device
)	O
and	O
Remote	B-Operating_System
Procedure	I-Operating_System
Call	I-Operating_System
(	O
RPC	O
)	O
applications	O
can	O
behave	O
in	O
this	O
manner	O
.	O
</s>
<s>
The	O
allocation	O
of	O
an	O
ephemeral	B-Protocol
port	I-Protocol
is	O
temporary	O
and	O
only	O
valid	O
for	O
the	O
duration	O
of	O
the	O
communication	O
session	O
.	O
</s>
<s>
After	O
completion	O
of	O
the	O
session	O
,	O
the	O
port	B-Protocol
is	O
destroyed	O
and	O
the	O
port	B-Protocol
number	I-Protocol
becomes	O
available	O
for	O
reuse	O
,	O
but	O
many	O
implementations	O
simply	O
increment	O
the	O
last	O
used	O
port	B-Protocol
number	I-Protocol
until	O
the	O
ephemeral	B-Protocol
port	I-Protocol
range	O
is	O
exhausted	O
,	O
when	O
the	O
numbers	O
roll	O
over	O
.	O
</s>
<s>
Ephemeral	B-Protocol
ports	I-Protocol
are	O
also	O
called	O
dynamic	B-Protocol
ports	I-Protocol
,	O
because	O
they	O
are	O
used	O
on	O
a	O
per	O
request	O
basis	O
,	O
and	O
are	O
only	O
known	O
by	O
number	O
once	O
allocated	O
.	O
</s>
<s>
The	O
RFC	O
6056	O
says	O
that	O
the	O
range	O
for	O
ephemeral	B-Protocol
ports	I-Protocol
should	O
be	O
1024	O
–	O
65535	O
.	O
</s>
<s>
Many	O
Linux	B-Operating_System
kernels	I-Operating_System
use	O
the	O
port	B-Protocol
range	O
32768	O
–	O
60999	O
.	O
</s>
<s>
FreeBSD	B-Operating_System
has	O
used	O
the	O
IANA	O
port	B-Protocol
range	O
since	O
release	O
4.6	O
.	O
</s>
<s>
Previous	O
versions	O
,	O
including	O
the	O
Berkeley	B-Operating_System
Software	I-Operating_System
Distribution	I-Operating_System
(	O
BSD	B-Operating_System
)	O
,	O
use	O
ports	O
1024	O
–	O
5000	O
as	O
ephemeral	B-Protocol
ports	I-Protocol
.	O
</s>
<s>
Microsoft	B-Application
Windows	I-Application
operating	I-Application
systems	I-Application
through	O
Windows	B-Application
XP	I-Application
use	O
the	O
range	O
1025	O
–	O
5000	O
as	O
ephemeral	B-Protocol
ports	I-Protocol
by	O
default	O
.	O
</s>
<s>
Windows	B-Application
Vista	I-Application
,	O
Windows	B-Device
7	I-Device
,	O
and	O
Server	B-Device
2008	I-Device
use	O
the	O
IANA	O
range	O
by	O
default	O
.	O
</s>
<s>
Windows	B-Application
Server	I-Application
2003	I-Application
uses	O
the	O
range	O
10255000	O
by	O
default	O
,	O
until	O
Microsoft	O
security	O
update	O
MS08-037	O
from	O
2008	O
is	O
installed	O
,	O
after	O
which	O
it	O
uses	O
the	O
IANA	O
range	O
by	O
default	O
.	O
</s>
<s>
Windows	B-Device
Server	I-Device
2008	I-Device
with	O
Exchange	O
Server	B-Application
2007	O
installed	O
has	O
a	O
default	O
port	B-Protocol
range	O
of	O
102560000	O
.	O
</s>
<s>
Solaris	B-Application
OS	I-Application
uses	O
32768	O
–	O
65535	O
range	O
.	O
</s>
<s>
AIX	B-Application
OS	I-Application
uses	O
32768	O
–	O
65535	O
range	O
.	O
</s>
<s>
If	O
certain	O
server	B-Application
software	I-Application
is	O
used	O
,	O
that	O
uses	O
non-ephemeral	O
custom	O
port	B-Protocol
ranges	O
for	O
initiating	O
some	O
further	O
connections	O
,	O
it	O
needs	O
to	O
be	O
ensured	O
by	O
configuration	O
that	O
this	O
custom	O
port	B-Protocol
range	O
and	O
the	O
ephemeral	B-Protocol
port	I-Protocol
range	O
do	O
not	O
overlap	O
.	O
</s>
