Server Ports Basics You Must Know
In network technology, server ports are divided into physical ports and logical ports (or virtual ports). Physical ports are connectors used to connect other network devices, such as ethernet port, LAN port and USB port. The devices connected to these ports are usually ADSL Modem, hubs, switches, routers, etc. The logical port generally refers to the port in the TCP/IP protocol, and the port number ranges from 0 to 65535, such as port 80 for browsing web services, port 21 for FTP services, and so on. Hence, each server provides the corresponding services through different server ports. Sometimes a server may be a Web server, an FTP server, or a mail server at the same time.
What Are Server Physical Ports?
Server physical port is a visual port, an input and output interface required to connect a server to communicate with other devices or computer networks. Several different types of physical ports available on servers include VGA port, IPMI port, ethernet port, USB port, and serial port.
The VGA port is a graphics card port used to transmit video signals. The IPMI port is an intelligent platform management port used to manage servers.
The ethernet port is a connection port for computer network equipment and servers. The server LAN port is one of them, usually connected to a router. Its purpose is to complete the connection of wired network hardware of local area network, metropolitan area network and wide area network.
USB (Universal Serial Bus) is a server port used to connect devices such as a mouse, 4U chassis, and keyboard. The server USB port features plug-and-play and hot-swappable functions, which makes file copying or plug-in installation more convenient.
A server serial port, like COM port, is a standard cable port. This type of port allows the server to transmit data between serial ports and network devices, such as switches, microcomputers. The serial port allows you to use your computer to access, manage and configure remote devices over the network.
What Are the Server Logical Port Types?
With the development of the communication network, the physical port of the server port can no longer meet the network requirements, and the logical port emerges as the times require. Logical ports, also known as TCP/IP protocol ports, are classified into various types according to their properties and services. Each of them offers a different service.
Server Ports by Properties
According to the nature of the server ports, logical ports are divided into well-known ports, registered ports, and dynamic or private ports. Specific applications of these are as follows:
Well-known ports: The port numbers for recognized ports are from 0 to 1023. Usually, these ports are bound to a specific service, providing a certain service protocol from servers.
Registered ports: The port numbers of the registered ports are from 1024 to 49151, and they are also bound to some server services. However, these ports do not have clearly defined service objects, and different applications can redefine them according to their needs.
Dynamic or private ports: The port numbers for dynamic or private ports are from 49152 to 65535. In general, common services cannot be allocated to these ports, because these ports are vulnerable to Trojan horse attacks.
Server Ports by Services
Besides physical ports, server protocol ports provide more services. Because the communication between computers generally uses the TCP and UDP communication protocols, the server protocol ports are also divided into TCP ports and UDP ports. You can click here for server TCP ports list and UDP port list.
Common ports that use the TCP ports are as follows:
FTP：The file transfer protocol is a set of standard protocols for network file transfer. It works on the seventh layer of the OSI model and the fourth layer of the TCP model, namely the application layer. The FTP protocol allows server users to communicate with another host in the manner of file operations.
Telnet：It is a port used for remote login. You can connect to the computer remotely as your own identity through servers. This port also provides a communication service based on DOS mode.
SMTP：It is a protocol for e-mail transmission with a high degree of reliability. SMTP is a mail transfer service built on the FTP file transfer service. It is mainly used for mail information transfer between systems and provides notifications about incoming letters. This is also why the server is called a mail server.
POP3：It is used to receive mail, corresponding to SMTP, using port 110. When your servers have the corresponding POP3 protocol program, you can receive mail through the mail program.
The UDP protocol in server ports is a connectionless transport layer protocol, located in the OSI reference model, and is mainly used in data services that do not require packet transmission order. The UDP protocol applies to multiple applications running on the same server. Commonly used UDP port numbers are: 53 (DNS), 69 (TFTP), 161 (SNMP). The UDP protocols used include TFTP, SNMP, NFS, DNS, and BOOTP.
TCP vs UDP
The TCP and UDP protocol ports on the server ports provide different services for a wide variety of devices connected to the server, which allows them to coexist under the same IP address. So what is the difference between the TCP protocol port and the UDP protocol port? Here is the answer.
TCP ports provide a more reliable service link because they must establish endpoints between sending and receiving locations. These ports keep track of data, ensuring that packets are delivered to recipients in a safe and orderly manner.
The connection speed of the UDP port is faster, but the reliability is relatively low. These ports allow data to be sent out of order and do not track and inspect data like TCP ports. They are mainly used for speed-critical operations, such as online gaming or video conferencing.
How to Check the Logical Ports Opened by the Server?
If you want to know your server port information, you can view the port through Netstat command on your computer. The Netstat command is generally used to display statistical data related to IP, TCP, UDP, and ICMP protocols and to check the network connection of each server port of the machine. Netstat is a program that accesses the network and related information in the kernel. It can provide reports on TCP connections, TCP and UDP monitoring, and process memory management.
The purpose of knowing your server port information is to give you more control over your applications. Because these applications use specific server ports, you need to pay attention to them to ensure stability. If some ports are down or unusable, you must check the relevant ports to deal with them. Of course, you can also open a port by deploying a router to assign to other devices or applications. It should be noted that some ports must be manually manipulated to bypass the firewall and avoid being prevented from running.