184 CHAPTER 14: NETWORKING CONCEPTSPort 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 65535Well Known PortNumbersThe Well Known Ports are controlled and assigned by the InternetAssigned Numbers Authority (IANA) http://www.iana.org and on mostsystems can only be used by system processes, or by programs executedby privileged users. Many popular services, such as Web, FTP, SMTP/POP3e-mail, DNS and so forth operate in this range.The assigned ports use a small portion of the possible port numbers. Formany years the assigned ports were in the range 0–255. Recently, therange for the assigned ports managed by the IANA has been expanded tothe range 0–1023.Registered PortNumbersThe Registered Ports are not controlled by the IANA and on most systemscan be used by ordinary user processes or programs executed by ordinaryusers.While the IANA cannot control uses of these ports, it does list uses ofthese 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 portnumbers.Private Port Numbers The Private Ports are not controlled or recorded by the IANA and are usedin the development of new software and in bespoke programs which willbe used by few users only.The Private Ports are in the range 49152–65535.Virtual PrivateNetwork ServicesThis section contains the following: Introduction to Virtual Private Networks VPN ApplicationsDUA1611-0AAA02.book Page 184 Thursday, August 2, 2001 4:01 PM
