TCP port number range and classification

The range of port numbers is from 1~65535

The concept of port:
In network technology, the port has roughly two meanings: the first is the physical port, for example, ADSL Modem, hub, switch, router interface for connecting other network devices, such as RJ-45 Port, SC port and so on. The second is the logical port, generally refers to the TCP/IP protocol port, the range of port number from 0 to 65535, such as for browsing the Web services 80 port, for the FTP service 21 port and so on.

What we're going to introduce here is the logical port.

Classification Status:

(1) Recognized port (wellknownports)

From 0 to 1023, they are tightly bound (binding) to some services. Usually the communication of these ports clearly indicates the protocol of a certain service. For example: Port 80 is actually always HTTP traffic.

(2) Registration port (registeredports)

From 1024 to 49151. They are loosely tied to some services. This means that there are many services bound to these ports, which are also used for many other purposes. For example: Many systems handle dynamic ports starting around 1024.

(3) dynamic and/or private ports (dynamicand/orprivateports)

From 49152 to 65535. In theory, these ports should not be assigned to the service. In fact, machines typically allocate dynamic ports from 1024 onwards. But there are exceptions: Sun's RPC port starts at 32768.

System administrators can redirect ports: A common technique is to redirect one port to another address. For example, the default HTTP port is 80, and many people redirect it to another port, such as 8080. If this is changed, to access this article should use this address http://wwd.3322.net:8080/net/port.htm (of course, this is only a theoretical example). The redirect is implemented to hide the accepted default port and reduce the rate of damage. This way, if someone wants to attack a recognized default port, a port scan must be performed first. Most port redirection is similar to the original port, for example, where most HTTP ports change from 80:81,88,8000,8080,8888.

Reference:

Http://blog.sina.com.cn/s/blog_4bdf819f0100vryh.html

http://blog.csdn.net/hsj521li/article/details/7678880

Http://www.2cto.com/net/201203/124616.html