Port Scanner
Check whether common ports are open on a host to see which services are reachable. It is a quick connectivity check for troubleshooting your own servers and services.
Port Scanner
Quickly check if common ports are reachable on a domain or IP address.
What ports represent
A server can run many services at once, and ports are the numbered doors that separate them: web traffic on 80 and 443, email on 25, and so on. Scanning checks which of these doors respond, telling you whether a service is running and reachable from where you are testing.
This is useful when a site loads but a particular feature does not, or when you are confirming that a service you set up is actually exposed. Only scan hosts you own or have permission to test, since scanning others can violate terms or laws.
Interpreting the results
Open, closed, and filtered each mean something.
- Open: a service is listening and reachable on that port.
- Closed or filtered: nothing is responding, or a firewall is blocking it.
- An unexpectedly open port can be a security concern worth investigating.
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FAQs
What does an open port mean?▼
That a service is listening on that port and is reachable. For example, an open 443 means a secure web server is responding. A closed or filtered port means nothing answered or a firewall blocked the check.
Is it legal to scan any host?▼
Only scan hosts you own or have explicit permission to test. Scanning systems you do not control can breach terms of service or laws, so keep it to your own servers.
What are common ports I might check?▼
80 and 443 for web, 25 and 587 for email, 22 for SSH, 3306 for MySQL, among others. Each corresponds to a standard service.
Why is a port shown as filtered rather than closed?▼
Filtered usually means a firewall is silently dropping the request, so the scanner gets no response either way. Closed means the host actively refused. Both indicate the service is not reachable.
Does an open port mean I am at risk?▼
Not by itself, but unexpected open ports are worth investigating. Each open port is a potential entry point, so only the services you intend should be exposed.
Why might a scan from the browser be limited?▼
Browsers restrict raw network access for security, so a web-based scan checks reachability indirectly and may not match a full network scanner. Use it as a quick indicator.
Can a port be open locally but closed to the internet?▼
Yes. A service may listen on the server but be blocked by a firewall or router from outside, so it is reachable on the local network but not publicly.
Is a request sent to the host I scan?▼
Yes. Checking a port requires attempting to connect to it, so a request goes to the target host. Only scan hosts you are authorized to test.
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