Check Ports on IP-Addresses - Online Tool


Check, if Ports are open, on a specific IP-Address with the Online-Tool on this Website.

IPV4 / IPV6-Address
Port

PORT CHECK RESULTS:


Description

The online tool allows you to check if specific ports on a given IP address are open or closed. This is useful for troubleshooting network issues, ensuring services are running, or verifying firewall configurations.

The online tool establishes a server-sided TCP connection between our server and the specified IP address and port. If the connection is successful, it indicates that the port is open and accepting connections. If the connection fails, it can be suggested that the port is closed or filtered by a firewall.

Our Server's current IP-Address is 212.227.72.245

The Server is located in Germany.

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🔐 Understanding TCP and UDP Ports

In computer networking, ports are communication endpoints used by devices to send and receive data. They help direct traffic to the correct service or application running on a device. There are two main types of transport protocols that use ports:

🔗 TCP (Transmission Control Protocol)

  • Connection-Oriented: TCP requires a connection to be established before data is exchanged.
  • Reliable: It ensures all data packets are delivered in the correct order and checks for errors.
  • Use Cases: Commonly used for web browsing (HTTP/HTTPS), email (SMTP), and file transfers (FTP).

When checking if a TCP port is open, the client attempts to establish a connection using the TCP handshake. If the connection is successful, we can confidently say that the port is open and accepting connections.

📡 UDP (User Datagram Protocol)

  • Connectionless: UDP does not establish a connection before sending data.
  • Unreliable: There’s no guarantee that packets will arrive or be in order.
  • Use Cases: Used for fast, real-time applications like DNS queries, video streaming, VoIP, and gaming.

Since UDP does not use a connection handshake, there's no built-in mechanism to confirm if a port is open. If the server responds to a UDP packet, the port is likely open — but if there’s no response, we can’t be sure whether the port is closed or the response was simply dropped or ignored.

❓ Why Can Only TCP Ports Be Confirmed Open?

  • ✅ TCP: A successful handshake (connect) means the port is open.
  • ❌ UDP: No handshake. Lack of response may mean the port is closed, filtered, or just not responding — so there's no reliable way to confirm.

As a result, **TCP port scanning** is more accurate for detecting open services, while **UDP scanning** can produce uncertain or false-negative results.

📌 Summary

Protocol Connection Type Reliable? Can Confirm Open?
TCP Connection-Oriented Yes ✅ Yes
UDP Connectionless No ⚠️ Not reliably