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184 C
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14: N
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ONCEPTS
Port Numbers
The port numbers are divided into three ranges:
■
Well Known ports — those from 0 to 1023
■
Registered ports — those from 1024 to 49151
■
Dynamic or Private ports — those from 49152 to 65535
Well Known Port
Numbers
The Well Known Ports are controlled and assigned by the Internet
Assigned Numbers Authority (IANA)
http://www.iana.org
and on most
systems can only be used by system processes, or by programs executed
by privileged users. Many popular services, such as Web, FTP, SMTP/POP3
e-mail, DNS and so forth operate in this range.
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 the assigned ports managed by the IANA has been expanded to
the range 0–1023.
Registered Port
Numbers
The Registered Ports are not controlled by the IANA and on most systems
can be used by ordinary user processes or programs executed by ordinary
users.
While the IANA cannot control uses of these ports, it does list uses of
these ports as convenience.
The Registered Ports are in the range 1024–49151.
Visit
http://www.ietf.org/rfc/rfc1700.txt
for a list of IP port
numbers.
Private Port Numbers The Private Ports are not controlled or recorded by the IANA and are used
in the development of new software and in bespoke programs which will
be used by few users only.
The Private Ports are in the range 49152–65535.
Virtual Private
Network Services
This section contains the following:
■
Introduction to Virtual Private Networks
■
VPN Applications
DUA1611-0AAA02.book Page 184 Thursday, August 2, 2001 4:01 PM