Computer Ports Explained

A computer port is a physical or virtual interface on a computer or networking device that allows data to be transmitted and received. It serves as a point of connection for various external devices, peripherals, or networks. Computer ports enable communication and data exchange between the computer and other devices, both locally and across networks.

Computer ports can be categorized into two main types:

  1. Physical Ports: These are physical connectors on a computer or device that allow you to physically plug in cables or connectors. Examples of physical ports include USB ports, Ethernet ports, HDMI ports, audio jacks, and serial ports. Each type of physical port is designed for specific types of connections and data transfer.
  2. Virtual Ports: Also known as network ports or logical ports, these are software-based endpoints that facilitate communication between applications and services within a computer or over a network. Virtual ports are identified by numbers and are associated with specific protocols. Examples include TCP and UDP ports used in networking protocols.

Computer ports are crucial for various purposes:

  • Peripheral Connection: Physical ports allow you to connect external devices like printers, monitors, keyboards, mice, and USB drives to your computer.
  • Data Transfer: Ports enable data transfer between devices, such as copying files from a digital camera to a computer via a USB port.
  • Networking: Network ports facilitate communication between computers and devices over a network. Different services and applications use specific port numbers to send and receive data.
  • Audio and Video: Ports like HDMI or audio jacks allow you to connect your computer to displays, speakers, headphones, and other audiovisual equipment.
  • Charging and Power: Some ports, like USB ports, can provide power to connected devices, such as smartphones and tablets.
  • Internet Connectivity: Ethernet ports provide wired internet connectivity by connecting your computer to a local network or the internet.

Computer ports are essential components that enable connectivity, communication, and data exchange between a computer and other devices or networks. They play a crucial role in modern computing and are integral to the functionality and versatility of computers and related devices.

Virtual Computer Ports

Computer ports are identified by specific numbers, known as port numbers, which are used to designate the type of service or application that uses the port for communication. These port numbers are an integral part of the TCP/IP networking protocol suite and help ensure that data is routed correctly between different applications and devices.

Most Common Virtual Ports

Port Number      Service name  Transport protocol Description
7 Echo TCP, UDP Echo service
20 FTP-data  TCP, SCTP File Transfer Protocol data transfer
21 FTP  TCP, UDP, SCTP File Transfer Protocol (FTP) control connection
22 SSH-SCP TCP, UDP, SCTP  Secure Shell, secure logins, file transfers (scp, sftp), and port forwarding
23 Telnet TCP Telnet protocol—unencrypted text communications
25 SMTP TCP  Simple Mail Transfer Protocol, used for email routing between mail servers
53 DNS TCP, UDP  Domain Name System name resolver
69 TFTP UDP Trivial File Transfer Protocol
80 HTTP TCP, UDP, SCTP Hypertext Transfer Protocol (HTTP) uses TCP in versions 1.x and 2.

HTTP/3 uses QUIC, a transport protocol on top of UDP

88 Kerberos TCP, UDP Network authentication system
102 Iso-tsap TCP ISO Transport Service Access Point (TSAP) Class 0 protocol
110 POP3 TCP Post Office Protocol, version 3 (POP3)
135 Microsoft EPMAP TCP, UDP Microsoft EPMAP (End Point Mapper), also known as DCE/RPC Locator service, used to remotely manage services including DHCP server, DNS server, and WINS. Also used by DCOM
137 NetBIOS-ns TCP, UDP  NetBIOS Name Service, used for name registration and resolution
139 NetBIOS-ssn TCP, UDP NetBIOS Session Service
143 IMAP4 TCP, UDP  Internet Message Access Protocol (IMAP), management of electronic mail messages on a server
161 SNMP UDP Simple Network Management Protocol (SNMP)
162 SNMPTRAP UDP Simple Network Management Protocol Trap (SNMPTRAP)
381 HP Openview TCP, UDP HP data alarm manager
383 HP Openview TCP, UDP HP performance data collector.
443 HTTP over SSL TCP, UDP, SCTP Hypertext Transfer Protocol Secure (HTTPS) uses TCP in versions 1.x and 2. HTTP/3 uses QUIC, a transport protocol on top of UDP.
464 Kerberos TCP, UDP Kerberos Change/Set password
465 SMTP over TLS/SSL, SSM TCP Authenticated SMTP over TLS/SSL (SMTPS), URL Rendezvous Directory for SSM (Cisco protocol)
587 SMTP TCP Email message submission
593 Microsoft DCOM TCP, UDP HTTP RPC Ep Map, Remote procedure call over Hypertext Transfer Protocol, often used by Distributed Component Object Model services and Microsoft Exchange Server
636 LDAP over TLS/SSL TCP, UDP Lightweight Directory Access Protocol over TLS/SSL
691 MS Exchange TCP MS Exchange Routing
902 VMware Server unofficial VMware ESXi
989 FTP over SSL TCP, UDP FTPS Protocol (data), FTP over TLS/SSL
990 FTP over SSL TCP, UDP  FTPS Protocol (control), FTP over TLS/SSL
993 IMAP4 over SSL TCP Internet Message Access Protocol over TLS/SSL (IMAPS)
995 POP3 over SSL TCP, UDP Post Office Protocol 3 over TLS/SSL
1025 Microsoft RPC TCP Microsoft operating systems tend to allocate one or more unsuspected, publicly exposed services (probably DCOM, but who knows) among the first handful of ports immediately above the end of the service port range (1024+).
1194 OpenVPN TCP, UDP OpenVPN
1337 WASTE unofficial WASTE Encrypted File Sharing Program
1589 Cisco VQP TCP, UDP Cisco VLAN Query Protocol (VQP)
1725 Steam UDP Valve Steam Client uses port 1725
2082 cPanel unofficial cPanel default
2083 radsec, cPanel TCP, UDP  Secure RADIUS Service (radsec), cPanel default SSL
2483 Oracle DB TCP, UDP Oracle database listening for insecure client connections to the listener, replaces port 1521
2484 Oracle DB TCP, UDP Oracle database listening for SSL client connections to the listener
2967 Symantec AV TCP, UDP Symantec System Center agent (SSC-AGENT)
3074 XBOX Live TCP, UDP Xbox LIVE and Games for Windows – Live
3306 MySQL TCP  MySQL database system
3724 World of Warcraft TCP, UDP Some Blizzard games, Unofficial Club Penguin Disney online game for kids
4664 Google Desktop unofficial Google Desktop Search
5432 PostgreSQL TCP PostgreSQL database system
5900 RFB/VNC Server TCP, UDP virtual Network Computing (VNC) Remote Frame Buffer RFB protocol
6665-6669 IRC TCP Internet Relay Chat .
6881 BitTorrent unofficial BitTorrent is part of the full range of ports used most often
6999 BitTorrent unofficial BitTorrent is part of the full range of ports used most often
6970 Quicktime unofficial QuickTime Streaming Server
8086 Kaspersky AV TCP Kaspersky AV Control Center
8087 Kaspersky AV UDP Kaspersky AV Control Center
8222 VMware Server TCP, UDP VMware Server Management User Interface (insecure Web interface).
9100 PDL TCP PDL Data Stream, used for printing to certain network printers.
10000 BackupExec unofficial Webmin, Web-based Unix/Linux system administration tool (default port)
12345 NetBus unofficial NetBus remote administration tool (often Trojan horse).
27374 Sub7 unofficial Sub7 default
31337 Back Orifice unofficial Back Orifice 2000 remote administration tools

Physical Computer Ports

While there are service application computer ports, there are other ports a computer utilizes. Computer ports are physical or virtual interfaces on a computer system that allow communication between the computer and external devices. These ports serve as entry and exit points for data and signals, enabling the computer to interact with various hardware components, peripherals, and networks. Each port type has a specific purpose and is designed to handle particular types of data or communication protocols.

Here are some common types of computer ports:

  1. USB (Universal Serial Bus) Ports: USB ports are widely used for connecting a variety of peripherals, such as keyboards, mice, printers, external hard drives, USB flash drives, cameras, and smartphones. USB ports provide a versatile and convenient way to transfer data and provide power to devices.
  2. Ethernet Port: The Ethernet port, also known as an RJ45 port, is used to connect a computer to a local area network (LAN) using an Ethernet cable. It enables high-speed data transfer and internet connectivity.
  3. HDMI (High-Definition Multimedia Interface) Port: HDMI ports are used to connect a computer to external displays, such as monitors, projectors, and TVs, to transmit high-definition audio and video signals.
  4. DisplayPort: Similar to HDMI, DisplayPort is used for connecting computers to displays. It supports high-resolution video and audio and is commonly found on laptops and desktop computers.
  5. Audio Ports: These include headphone jacks and microphone jacks, allowing you to connect audio devices such as headphones, speakers, and microphones to your computer.
  6. VGA (Video Graphics Array) Port: VGA ports are used to connect older displays, such as CRT monitors and projectors, to computers. They transmit analog video signals.
  7. Thunderbolt Ports: Thunderbolt ports offer high-speed data transfer and can also support video output. They are used to connect devices like external hard drives, monitors, and docking stations.
  8. Serial and Parallel Ports: While less common in modern computers, these ports were used in the past for connecting peripherals like printers and serial devices.
  9. PS/2 Ports: These are used for connecting keyboards and mice to computers. They have largely been replaced by USB ports.
  10. Card Slots: Some computers have slots for various types of expansion cards, such as graphics cards, sound cards, and network interface cards.
  11. FireWire (IEEE 1394) Ports: FireWire ports were used for high-speed data transfer and connecting devices like digital cameras and external hard drives. They are less common today.
  12. SIM Card Slot: Found in laptops and devices with cellular capabilities, SIM card slots allow connection to mobile networks.

Computer ports are essential for establishing connections between a computer and external devices, enabling data transfer, communication, and interaction. Different types of ports serve different purposes and support various protocols, making them crucial components for expanding the functionality of a computer system.


Computer ports are essential communication endpoints that allow different applications and services to interact over a network. They facilitate data transmission and reception, enabling various functions in networking and computing:

  1. Service Differentiation: Ports are numbered to differentiate between different services and applications running on a device. This ensures that data is sent to the appropriate destination based on the specific port number.
  2. Application Communication: Ports enable applications to communicate with each other locally or across networks. They provide a standardized way for software to send and receive data, supporting tasks like file transfer, email exchange, web browsing, and more.
  3. Network Routing: Ports play a role in routing data within a network. Routers and switches use port numbers to direct data packets to the correct devices or services.
  4. Firewall and Security: Ports are used in firewall configurations to control data flow and protect systems. By allowing or blocking specific port numbers, administrators can enhance security by managing access to services.
  5. Load Balancing: In server environments, load balancers distribute incoming traffic across multiple servers based on port numbers, optimizing resource utilization and ensuring high availability.
  6. Internet Services: Ports enable internet-based services like web hosting, email, and remote access. Web servers, email servers, and VPNs use specific port numbers to provide these services.
  7. Network Troubleshooting: Port numbers help diagnose network issues. Analyzing which ports are open or blocked can help identify communication problems and pinpoint areas of concern.
  8. Application Development: Developers use port numbers to create networked applications that can communicate with other software or services, enabling collaborative and distributed functionality.
  9. Protocol Implementation: Different protocols, such as TCP and UDP, use ports to establish connections and manage data transfer. Port numbers define the behavior and rules for protocol communication.
  10. Versatility: The vast range of port numbers accommodates numerous services simultaneously, allowing devices to handle various tasks concurrently.

In closing, computer ports are critical for seamless communication and data exchange between applications, devices, and services in both local and global network environments. They are fundamental components of modern networking that contribute to efficient and organized data flow while enhancing security and enabling a wide range of functionalities.

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