免費線上連接埠檢查器

What is a port checker?

UrwaTools Port Checker is a free, easy-to-use online tool that helps you see which ports are open on your computer or device. It’s ideal for testing port forwarding on your router and spotting problems caused by blocked ports in your firewall or by your ISP. If an app like email, chat, or a game isn’t connecting, you can quickly check whether its required port is open or closed. It’s also useful for basic security checks when you’re not sure which ports are exposed. If you host games like a Minecraft server, you can use this tool. It helps you check if port 25565 is set up right. This way, your friends can join without any connection problems.

What Is a Port in Networking?

A port is a communication endpoint used by devices and applications to send and receive data over a network. Every connection—whether wired or wireless—ultimately reaches a port on a device. In an operating system, a port is a logical point that links network traffic to a specific app, process, or service (such as a web server or email client).

Ports are identified by 16-bit unsigned numbers ranging from 0 to 65,535 and work together with an IP address and protocol. The most common protocols that use port numbers are TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).

Types of Port Numbers and Ranges

Port numbers are grouped into well-defined ranges:

• Well-known ports (1–1023)
•  These are fixed ports reserved for standard internet services. For example:
• Port 25 – SMTP (email sending)
• Port 80 – HTTP (web traffic)
• Registered / Ephemeral ports (1024–65,535)
•  Client applications typically use these ports for temporary connections. They are often called ephemeral ports because they are assigned for a short time while the connection is active and then released.

Understanding port numbers and their ranges helps you troubleshoot network issues, configure firewalls, and use tools like an online port checker more effectively.

Free Online Port Checker – Quickly Test Open Ports

Use our free online Port Checker to see instantly whether a port is open or closed on your network. It runs reliable TCP and UDP checks to give you accurate results, helping you understand connectivity issues and spot basic security risks in seconds.

Think of it as a smart inspector for your device’s “front doors” (ports). It quietly checks each selected port and tells you if it’s open, closed, or not responding—no technical setup required.

You can test a single port or a few specific ones used for games, apps, remote access, file sharing, or other services. You can also scan the most common ports that are often used across the internet. With just a couple of clicks, the UrwaTools Port Checker shows you exactly what’s open and what needs attention.

How to Use Our Port Checker

Our online Port Checker is built to be powerful but simple so that anyone can scan ports in just a few steps. Here’s how to run a quick port test:

Enter the Domain or IP address.

 Type the domain name or IP address you want to test into the input field. It can be your own device, a remote server, or any host you’re allowed to scan.

Choose How You Want to Select Ports

 By default, the tool opens with Custom Ports selected. You can:

Manually enter one or more port numbers you want to check, or

Pick from ready-made port groups if you don’t remember exact numbers:

• Server Ports
• Game Ports
• Application Ports
• P2P Ports

To make things even easier, our port checker also shows a full list of common ports. You can click any port number to add it or scan all common ports in a single run.

Start the Port Scan

 Click the “Check” button to start scanning. The tool will test each selected port and show you the live results.

Read the Results

If a port is reachable, it will be marked as “Open”.

If you see “Timed out”, it usually means the port is blocked, filtered, or not responding.

In just a few seconds, you’ll know which ports are open, closed, or unavailable—helping you debug connection issues and understand your network security at a glance.

Common Port Number Ranges

Port numbers go from 1 to 65,535, but not all of them are used in the same way. Many popular services use standard, well-known ports defined by IANA. Here’s a quick, easy guide:

• 0–1023 – Well-Known Ports
•  Used by core internet services such as HTTP (web), HTTPS, SMTP (email), DNS, DHCP, FTP and others.
• 1024–49,151 – Registered Ports
•  Assigned to specific applications and services. Software, servers and network tools often use these.
• 49,152–65,535 – Dynamic / Private Ports
•  Used for temporary connections. Your system and apps often use these ports automatically for outbound traffic and short-lived sessions.

How to Find Your Port Number (Windows & Mac)

Sometimes you need to know which ports your computer or server is using—for example, when setting up port forwarding, hosting a game server, or fixing connection issues. Here’s how to quickly find port numbers on different operating systems.

On Windows

• Open Command Prompt
•  Press Win + R, type cmd, and press Enter.
• Check your network details (optional)
•  Type ipconfig and press Enter to see your local IP and network information.
• List active ports
•  Type netstat -a and press Enter.
•  Windows will display a list of active connections along with the local port numbers currently in use.

On macOS

1. Open Network Utility or Terminal

• Press Command + Space, search for “Network Utility” (on older macOS), or
• Open Terminal from Applications → Utilities.

     2. Use Port Scan (Network Utility)

• In Network Utility, go to the Port Scan tab.
• Enter the IP address or hostname you want to check.
• Click Scan to see which ports are open.

    3. OR, using Terminal:

•  Run a simple command like:
• netstat -an
• It will list active connections and the ports your Mac is using.

With these steps, you can quickly find and confirm the port numbers needed for your apps, servers, and port checker tests.

Common Well-Known Ports and What They’re Used For

Here’s a simple, easy-to-scan list of popular, well-known ports. These are the ports you’ll most often check when troubleshooting network issues or testing services with the UrwaTools Port Checker:

• 20 & 21 – FTP
•  File Transfer Protocol, used for uploading and downloading files between client and server.
• 22 – SSH
•  Secure Shell, used for secure remote login and command-line access.
• 23 – Telnet
•  Legacy remote login service, mostly replaced by SSH due to security risks.
• 25 – SMTP
•  Simple Mail Transfer Protocol, used for sending email between mail servers.
• 53 – DNS
•  The Domain Name System translates domain names (like example.com) into IP addresses.
• 80 – HTTP
•  Hypertext Transfer Protocol is standard web traffic for non-encrypted websites.
• 110 – POP3
•  Post Office Protocol 3, used by email clients to download messages from a mail server.
• 115 – SFTP
•  Simple File Transfer Protocol (legacy file transfer service, now rarely used).
• 123 – NTP
•  Network Time Protocol keeps device clocks in sync over the Internet.
• 143 – IMAP
•  Internet Message Access Protocol lets email clients read mail directly on the server.
• 161 – SNMP
•  Simple Network Management Protocol, used for monitoring and managing network devices.
• 194 – IRC
•  Internet Relay Chat, used for real-time text chat channels and groups.
• 443 – HTTPS / SSL
•  Secure HTTP encrypts web traffic for secure browsing (padlock in your browser).
• 445 – SMB
•  Server Message Block, used for file and printer sharing on local networks.
• 465 – SMTPS
•  SMTP over SSL sends email securely using encryption.
• 554 – RTSP
•  Real Time Streaming Protocol, used for audio and video streaming control.
• 873 – RSYNC
•  rsync file transfer service, popular for backups and file synchronisation.
• 993 – IMAPS
•  IMAP over SSL, secure access to email on the server.
• 995 – POP3S
•  POP3 over SSL, secure email download to a local client.
• 3389 – RDP
•  Remote Desktop Protocol, used for remote graphical access to Windows machines.
• 5631 – PC Anywhere
•  Remote control and support software port (Symantec pcAnywhere).
• 3306 – MySQL
•  Default port for MySQL database servers.
• 5432 – PostgreSQL
•  Default port for PostgreSQL database servers.
• 5900 – VNC
•  Virtual Network Computing, used for remote desktop sharing.
• 6379 – Redis
•  Default port for Redis in-memory data store and cache.
• 8333 – Bitcoin
•  Default port for Bitcoin nodes on the peer-to-peer network.
• 11211 – Memcached
•  Default port for Memcached caching servers.
• 25565 – Minecraft
•  Default port for Minecraft Java Edition servers.

These ports are a great starting point when checking if a service is reachable or if a firewall or router is blocking traffic.

If you want to see every assigned port number, you can check this trusted full port list. I’ve already listed the most common ports above, but you can enter any custom port number into the checker to test it. The tool uses your device’s IP address by default. It is the address you are using to visit this page. However, you can change the IP field to scan a different address. It could be a remote server or client. Please use this feature carefully. If misused, we may limit scans to your own source IP again, like before. Also, remember that if you are using a VPN or proxy, the tool may not detect your real device IP correctly.

What Is Port Forwarding?

Port forwarding (also called port mapping) is a way to send internet traffic from your router to the right device inside your private network. The router does not block the request. Instead, it accepts incoming packets on a specific port. Then, it forwards them to a selected computer using its routing rules. You can read a clear technical overview of port forwarding if you want more details.

Port forwarding helps remote devices connect to certain apps or services on a computer in your LAN. You might run a web server on port 80. You could also host a game server or allow SSH access to one machine on your network. By opening and forwarding only the ports you need, you can stay connected. It also helps you keep better control over your network security.