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General Networking/Lan/Wan/TCP/IP and UDP Port Numbers Nomenclature.

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Dear Sudhanshu

http://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers
http://www.webopedia.com/quick_ref/portnumbers.asp
http://www.stengel.net/tcpports.htm


1. As we see port numbers 4, 6, 8, 10, 12, 14, 16, 26, 40 ....
were kept as Unassigned, would like to know the reason for the same i.e. why those numbers were skipped ?.

2. If a new TCP/IP OR UDP Application or Service or protocol is designed and developed, Can we use these above Unassigned ports ?.

3. As we see the Maximum port number value is 61000, so If a new TCP/IP OR UDP Application or Service or protocol is designed and developed, Should we use 61001 as the port number ?.   


Thanks & Regards,
Prashant S Akerkar

Answer
Prashant,

They are kept reserved for internal use by IETF and lot of unused ports are for future use.

You can use unassigned ones so that it does not clash with any of the widely used port numbers.

You can, however you need to get an approval from IETF so that people across the globe and application vendors like MS, Oracle etc know which port number to access your application on.

Hope this helps.
sorry for delay in replying.
-sudhanshu

General Networking/Lan/Wan

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Sudhanshu Gupta

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Any question related to IP routing protocols - BGP/OSPF/IGRP/EIGRP/RIP, HSRP. Bridging/DLSW, Cisco routers and Switches, LAN/WAN installation and monitoring.

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I have about 14 yeras of experience in networking. I am an MCSE and CCIE (7334).

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