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Quickly check the open port status of an IP or domain for network diagnostics and security validation.
Port checking is used to verify whether a specific service is running and accessible on a server. It attempts to establish a TCP connection with the target port. If the connection is successful, the port is considered "open", and we can measure the "TCP Ping" latency (the time required to complete the connection handshake). If the connection fails or times out, the port is "closed" or filtered by a firewall.
Overview
Understand what the tool solves, how it works, and the boundaries of its data.
Enter a hostname or IP address and one or more TCP port numbers to attempt a connection from the checking service. A successful connection means a TCP connection was accepted from that service’s network location at that time. It does not test UDP, probe from your own device or Wi-Fi, or confirm what application is listening.
TCP establishes a connection between endpoints; this check attempts that connection and reports the host, port, whether it connected, elapsed connection time on success, or an error such as refusal or timeout. Results can vary by network route, firewall rules, host resolution, and server state.
Port input accepts individual numbers separated by commas and inclusive ranges such as 80,443,8000-8002. Values are filtered to the TCP port range 1–65535, duplicates are removed, and the remaining ports are checked in ascending order. A single submission can include up to 50 distinct valid ports. Common-service shortcuts can fill in frequently used ports, but they do not detect which service a server actually runs.
Protocol reference checked September 28, 2026
Guide
Follow the workflow and verify inputs and outputs with practical examples.
Enter a hostname or IP address for a system you own or are authorized to check. Confirm that the name or address is typed correctly.
Enter a port, comma-separated list, or range. For example, 443,8443 checks two TCP ports. Keep the set to 50 or fewer unique valid ports per run.
Run the check. An accepted connection is marked open and can include elapsed time. A failed attempt includes an error or timeout; it is not always enough to distinguish a closed service from filtering or a route problem.
Use cases
See how the tool fits into real work and everyday tasks.
An administrator can test TCP 443 on a managed hostname after configuring a service or firewall rule. A successful connection confirms reachability from this check’s location, then the administrator can test TLS and application behavior separately.
A support engineer can check a small list such as 80 and 443 on an authorized server to see whether connection attempts succeed from the service vantage point. Follow up from the user’s actual network if the reported problem is location-specific.
Q&A
Find concise answers to common questions and confusing cases.
No. It means a TCP connection was accepted from the checker’s network location. It does not validate encryption, authentication, application health, or configuration.
No. The connection attempt originates from the checking service, so firewalls and routes may differ from your own device or a customer’s network.
No. A refusal, timeout, DNS problem, firewall, or route issue can all prevent a successful connection. Use the returned error as a clue and verify from an authorized network.
Yes. Use commas and inclusive ranges, such as 80,443,8000-8003. The tool permits up to 50 unique valid TCP ports in one check.
Notes
Review scope, result limitations, and important precautions before use.
Only check hosts and ports you own or have explicit permission to test. This is a limited TCP reachability check, not a vulnerability scan, security assessment, UDP test, or guarantee that a service is available to every network. Avoid treating a single result as proof of security or as a complete diagnosis; confirm important findings with the system owner and from the relevant network.
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