The Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) are two of the most commonly used protocols for internet communication. Both of these protocols use what are known as port numbers to identify specific applications, services, or processes that are running on a particular device.

In this article, we will discuss some of the most popular TCP and UDP ports that are used across the internet for various purposes.

TCP Ports

1. Port 80

This port is used to access web servers and is the default port for HTTP (Hypertext Transfer Protocol) communication. Port 80 is typically used for web browsing and accessing websites.

2. Port 443

This port is used for secure web communication and is the default port for HTTPS (Hypertext Transfer Protocol Secure) communication. Port 443 is typically used when sensitive information such as login credentials or credit card information is being transmitted.

3. Port 25

This port is used for email communication and is the default port for SMTP (Simple Mail Transfer Protocol) communication. Port 25 is typically used for sending email from one email server to another.

4. Port 110

This port is used for email communication and is the default port for POP3 (Post Office Protocol version 3) communication. Port 110 is typically used for retrieving email from an email server.

5. Port 143

This port is used for email communication and is the default port for IMAP (Internet Message Access Protocol) communication. Port 143 is typically used for retrieving email from an email server.

UDP Ports

1. Port 53

This port is used for DNS (Domain Name System) communication. DNS is used to translate human-readable domain names (such as google.com) to IP addresses that can be understood by computers.

2. Port 67

This port is used for DHCP (Dynamic Host Configuration Protocol) communication. DHCP is used to assign IP addresses and other network settings to devices on a network.

3. Port 68

This port is also used for DHCP communication, but is used by client devices to request IP addresses and other network settings from a DHCP server.

4. Port 161

This port is used for SNMP (Simple Network Management Protocol) communication. SNMP is used to monitor and manage network devices such as routers, switches, and servers.

5. Port 123

This port is used for NTP (Network Time Protocol) communication. NTP is used to synchronize the time on devices across a network.

In conclusion, these TCP and UDP ports are just a few examples of the many ports that are commonly used across the internet for various purposes. Understanding the purpose and function of these ports can be helpful in troubleshooting network issues and ensuring that your devices are communicating properly.