This article provides information about port assignments for various TCP/IP
ports. This was previously documented in RFC 1700.
The assignments are now listed as living documents, regularly updated and
revised when new information is available and new assignments are made. The
specific location of the port numbers list is now available at the following Web site:
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PORT NUMBERS
The port numbers are divided into three ranges: the Well Known Ports, the
Registered Ports, and the Dynamic and/or Private Ports.
| • | The Well Known Ports are those from 0 through 1023. |
| • | The Registered Ports are those from 1024 through 49151. |
| • | The Dynamic and/or Private Ports are those from 49152 through 65535. |
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WELL KNOWN PORT NUMBERS
The Well Known Ports are assigned by the IANA and on most systems can only
be used by system (or root) processes or by programs executed by
privileged users. Ports are used in the TCP [RFC793] to name the ends of
logical connections which carry long term conversations. For the purpose
of providing services to unknown callers, a service contact port is
defined.
The contact port is sometimes called the "well-known port" .To the extent
possible, these same port assignments are used with the UDP [RFC768]. The
assigned ports use a small portion of the possible port numbers. For many
years the assigned ports were in the range 0-255. Recently, the range for
assigned ports managed by the IANA has been expanded to the range 0-1023.
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REGISTERED PORT NUMBERS
The Registered Ports are listed by the IANA and on most systems can be
used by ordinary user processes or programs executed by ordinary users.
Ports are used in the TCP [RFC793] to name the ends of logical connections
which carry long term conversations. For the purpose of providing services
to unknown callers, a service contact port is defined.
The IANA registers uses of these ports as a convenience to the community.
To the extent possible, these same port assignments are used with the UDP
[RFC768]. The Registered Ports are in the range 1024-49151.
For information about specific TCP/IP port assignments, see RFC 1700 on
the Information Sciences Institute Web site at the following location:
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