What are The Well-Known Port Numbers?

well known ports
3 min read

A port number is a 16-bit numeric value that oscillates between 0 and 65535. There are three different types of port numbers: well-known ports, registered ports, and dynamic ports. Therefore, making port numbers an essential part of network communication. Consequently, make sure to review these while studying for your next certification (CCNA or CompTIA Network+).

First of all, these port numbers are reserved by ICANN. The Internet Committee for Assigned Names and Numbers and oversees the use of Internet domains. These well-known ports are used by your computer application to communicate. This communication is established using the Internet’s Transmission Control Protocol (TCP) or the User Datagram Protocol (UDP). 

How does a port work?

Firstly, let’s begin by clarifying that a computer has two types of ports physical ports and network communication ports. A physical port allows computers to communicate with peripheral devices. It is defined as a computer point of entry for communication. Consequently, a physical port is where communication begins or ends on a physical device. A physical port’s basic job is the reading and transmission of data.

On the other hand, a network communication port allows communication between computers on a network. They are provided by the TCP or UDP protocols at the Transport layer. These port numbers are used to determine what protocol incoming traffic should be directed to. 

Types of communication ports

The three types of communication ports are well-known ports, registered ports, and dynamic ports.

  • Well-known ports cover the range of possible port numbers from 0 through 1023.
  • Registered ports are numbered from 1024 through 49151.
  • Dynamic ports or private ports are numbered from 49152 through 65535.

Here are the Common Network Ports you need to know before your CCNA or CompTIA Network+ exam.

Well-Known Port Numbers Cheat Sheet

PortService nameDescription
 TCP/20 TCP/21 File Transfer Protocol (FTP) Sends and receives files between systems
 TCP/22 Secure Shell (SSH) Encrypted console login
TCP/22Secure FTP (SFTP)Secure File Transfer
 TCP/23 Telnet Remote console login to network devices
 TCP/25 Simple Mail Transfer Protocol (SMTP) Transfer emails between email servers
 UDP/53 Domain Name System (DNS)Convert domains into IP address
 Dynamic Host Configuration Protocol (DHCP) Automated IP addressing and configuration
 UDP/69 Trivial File Transfer Protocol (TFTP) A very simple file transfer applications
 TCP/80 HyperText Transfer Protocol (HTTP) Web server communication
 TCP/110 Post Office Protocol (POP3) Receive mail into a mail client
 UDP/123 Network Time Protocol (NTP) Synchronize Clocks
 TCP/143 Internet Message Access Protocol (IMAP4)A newer mail client protocol
 UDP/161 Simple Network Management Protocol (SNMP)Gather statistics and manage network devices
TCP/389 Lightweight Directory Access Protocol (LDAP)Communicate with network directories
TCP/443 Hypertext Transfer Protocol Secure (HTTPS)Web server communication with encryption
TCP/445Server message block (SMB) Windows file transfers and printer sharing
TCP/636Lightweight Directory Access Protocol Secure (LDAPS)LDAP over SSL
 TCP/3389 Remote Desktop Protocol (RDP)Graphical display of remote device
H.323ITU Telecommunication H.32x protocol seriesVoice over IP signaling
TCP/5060-5061Session Initiation Protocol (SIP)Voice over IP signaling protocol

Victor Hugo Solis

Master’s Degree in Information Security, a Bachelor’s Degree in Database Administration, and experience as a WordPress Web Designer & Developer.