<s>
A	O
registered	B-Protocol
port	I-Protocol
is	O
a	O
network	B-Protocol
port	I-Protocol
designated	O
for	O
use	O
with	O
a	O
certain	O
protocol	O
or	O
application	O
.	O
</s>
<s>
Registered	B-Protocol
port	I-Protocol
numbers	O
are	O
currently	O
assigned	O
by	O
the	O
Internet	O
Assigned	O
Numbers	O
Authority	O
(	O
IANA	O
)	O
and	O
were	O
assigned	O
by	O
Internet	B-Application
Corporation	I-Application
for	I-Application
Assigned	I-Application
Names	I-Application
and	I-Application
Numbers	I-Application
(	O
ICANN	B-Application
)	O
before	O
March	O
21	O
,	O
2001	O
,	O
and	O
were	O
assigned	O
by	O
the	O
Information	O
Sciences	O
Institute	O
(	O
USC/ISI	O
)	O
before	O
1998	O
.	O
</s>
<s>
Ports	O
with	O
numbers	O
0	O
–	O
1023	O
are	O
called	O
system	O
or	O
well-known	O
ports	O
;	O
ports	O
with	O
numbers	O
1024-49151	O
are	O
called	O
user	O
or	O
registered	B-Protocol
ports	I-Protocol
,	O
and	O
ports	O
with	O
numbers	O
49152-65535	O
are	O
called	O
dynamic	B-Protocol
,	I-Protocol
private	I-Protocol
or	I-Protocol
ephemeral	I-Protocol
ports	I-Protocol
.	O
</s>
<s>
Both	O
system	O
and	O
user	O
ports	O
are	O
used	O
by	O
transport	O
protocols	O
(	O
TCP	B-Protocol
,	O
UDP	B-Protocol
,	O
DCCP	B-Protocol
,	O
SCTP	B-Protocol
)	O
to	O
identify	O
an	O
application	O
or	O
service	O
.	O
</s>
