Network port number layout and classification

1. What is a network port
in theNetwork Technology, the port has roughly two meanings:first, the physical port, for example, the ADSL Modem,hubs,Switch,Routersan interface for connecting to other network devices, such asRJ-45 Port, SC port and so on;two. A logical port, generally referred to asTCP/IP protocolin the port,Port numberrange from 0 to 65535, such as 80 ports for browsing Web services, 21 ports for FTP services, and so on.

2.Port Classification

(1) by port number can be divided into 3 major categories:

<1> recognized ports (well known Ports): 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.

these ports usually do not take advantage of hacking programs like Trojans. In order to give you a little more understanding of these common ports, we will give you a detailed list of the services that should be provided across these ports later in this chapter for your understanding and reference.

<2> Register port (registered Ports): 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.

Most of these ports do not explicitly define the service object, the different programs can be defined according to the actual needs, such as the remote control software and Trojan horse program to be described in the following will have the definition of these ports. Keep in mind that these common program ports are necessary to protect and Avira Trojan horse programs. The port used by the common Trojan will be followed by a detailed list.

<3> dynamics and/or private ports (dynamic and/or private Ports): 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.

In addition, some of the more special programs, especially some Trojan horse programs are very like to use these ports, because these ports are often not attracted attention, easy to hide.

(2) Classification by Protocol type

Divided by protocol type, it can be divided into TCP, UDP, IP and ICMP (Internet Control Message Protocol) and other ports. The following mainly describes TCP and UDP ports:

<1> TCP Ports

TCP ports, or Transmission Control protocol ports, require a connection between the client and the server to provide reliable data transfer. Common 21 ports include the FTP service, 23 ports for the Telnet service, 25 ports for the SMTP service, and 80 ports for the HTTP service, and so on.

<2> UDP ports

UDP port, the user Packet protocol port, does not require a connection between the client and the server, and security is not guaranteed. Common DNS Service has 53 ports, SNMP (Simple Network Management Protocol) service 161 port, QQ uses 8000 and 4000 ports and so on.

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Network port number layout and classification