Most Used Network Ports: Complete Guide

Every connection on the Internet uses a port number alongside an IP address. Ports tell the receiving computer which service the data is intended for. Understanding common ports is essential for network administrators, developers, and anyone interested in cybersecurity.

What is a Network Port?

A port is a number from 0 to 65535 that identifies a specific service on a device. When you visit a website, your browser connects to port 443 (HTTPS). When you send an email, your client connects to port 587 (SMTP). The combination of IP address + port uniquely identifies a connection endpoint.

Ports are divided into three ranges:

• Well-known ports (0-1023): Assigned by IANA for standard services (HTTP, SSH, DNS, etc.)
• Registered ports (1024-49151): Assigned to specific applications (MySQL, PostgreSQL, etc.)
• Dynamic ports (49152-65535): Temporarily assigned by the OS for outgoing connections

The 20 Most Important Ports

Essential Ports Explained

Port 80 (HTTP)

The default port for unencrypted web traffic. Modern sites redirect HTTP to HTTPS (port 443). If you see "http://" in your browser, data is sent in plaintext and can be intercepted.

Port 443 (HTTPS)

The default port for encrypted web traffic using TLS. Every modern website should use HTTPS. Google marks HTTP sites as "Not secure" and gives HTTPS a ranking boost.

Port 22 (SSH)

Secure Shell — used for encrypted remote access to servers. Essential for system administration. Change the default port or use key-based authentication for better security.

Port 53 (DNS)

Domain Name System — translates domain names to IP addresses. Uses both TCP and UDP. You can check DNS records using our DNS lookup tool.

Security Best Practices

• Close unused ports: Every open port is a potential attack surface
• Use firewalls: Block all ports except those you explicitly need
• Never expose databases: MySQL, PostgreSQL, Redis, and MongoDB should never be accessible from the Internet
• Use encrypted alternatives: HTTPS over HTTP, SSH over Telnet, IMAPS over IMAP
• Change default ports: Moving SSH from 22 to a non-standard port reduces automated attacks

How to Check Open Ports

Use the port scanner on miip.link to check which ports are open on any host. Or use command-line tools:

# Check if a port is open
nc -zv example.com 443

# Scan common ports with nmap
nmap -F example.com

# Check what's listening on your machine
netstat -tlnp    # Linux
netstat -an | grep LISTEN  # macOS

FAQ

Can two services use the same port?

No. Only one service can listen on a port at a time. If you get "address already in use" errors, another service is already using that port.

Should I change the SSH port?

Changing from port 22 to a non-standard port (like 2222) reduces automated scan noise, but it's security through obscurity. Use key-based authentication and disable password login for real security.

What ports should I block?

Block everything by default, then open only what you need. At minimum, block: Telnet (23), FTP (21), and any database ports (3306, 5432, 6379, 27017) from the Internet.