Network Port Checker

Explore common network ports, learn what services use them, and understand their security implications. Search for specific ports or browse the comprehensive reference guide below.

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Important: Browsers cannot directly scan ports due to security restrictions. This tool provides educational information about network ports and their common uses. For actual port scanning, use dedicated tools like nmap, netcat, or online port scanning services.

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Common Network Ports Reference

Port Protocol Service Description Security

Port Number Ranges

0 - 1023
Well-Known Ports
Reserved for common services like HTTP, FTP, SSH. Require root/admin privileges to bind.
1024 - 49151
Registered Ports
Assigned by IANA for specific services. Used by applications like databases and game servers.
49152 - 65535
Dynamic/Private Ports
Ephemeral ports used for temporary connections. Assigned dynamically by the OS.

Port Security Best Practices

1

Close Unused Ports

Only open ports that are necessary for your services. Each open port is a potential entry point for attackers.

2

Use Encrypted Protocols

Prefer HTTPS (443) over HTTP (80), SFTP (22) over FTP (21), and IMAPS (993) over IMAP (143).

3

Configure Firewalls

Use firewalls to restrict access to ports based on IP addresses and implement rate limiting.

4

Monitor Port Activity

Regularly audit open ports and monitor for unusual connection attempts or traffic patterns.

About Network Ports

Network ports are virtual endpoints that allow computers to distinguish between different types of network traffic. Think of them as apartment numbers in a building - the IP address gets you to the building, and the port number directs you to the specific apartment (service).

TCP vs UDP

TCP (Transmission Control Protocol) provides reliable, ordered delivery of data. It establishes a connection before transmitting and confirms receipt of data. Used for web browsing, email, and file transfers where data integrity is crucial.

UDP (User Datagram Protocol) is connectionless and faster but doesn't guarantee delivery. Used for streaming media, online gaming, and DNS queries where speed matters more than perfect reliability.

Why Browsers Cannot Scan Ports

Web browsers implement strict security policies that prevent JavaScript from creating raw TCP/UDP socket connections. This is intentional - if browsers could scan ports, malicious websites could:

  • Scan your local network for vulnerable devices
  • Fingerprint your system and installed services
  • Conduct distributed denial-of-service attacks
  • Bypass corporate firewalls from the inside

How to Actually Check Ports

For real port checking, use these methods:

  • Command Line: Use netstat, ss, or lsof to view open ports on your system
  • Nmap: The industry-standard port scanner for network discovery
  • Online Services: Websites like canyouseeme.org can check if specific ports are accessible from the internet
  • Telnet/Netcat: Test individual port connectivity with telnet host port or nc -vz host port

This tool is for educational purposes only. Always ensure you have authorization before scanning ports on networks or systems you don't own.