Fusion Proxy
LoginGet Started

Free Network Tool

Online port scanner

Check whether a curated list of common service ports is reachable on a single host. Useful for verifying that a server you control is exposing the services you expect — not for probing arbitrary infrastructure.

20 ports max per scan3 curated presetsPrivate & reserved ranges blockedNo arbitrary ranges
Selected list: Common ports · 18 ports

We do not support arbitrary ranges, custom port lists, or scans against private addresses. Each scan checks at most 20 explicit ports against one host.

When this tool helps

The scanner is meant for owners and operators who want to confirm a server is exposing the services they meant to expose — the modern equivalent of checking whether you remembered to open port 443 in the firewall after a deploy.

Confirm a deploy

After standing up a new server, run a scan to verify the right ports are reachable from outside.

Catch a regression

If a service stops responding, a quick scan separates a port-level issue from an application-level one.

Audit a firewall change

Scan before and after an iptables or security-group change to verify the change did what you intended.

Verify a managed proxy

If you’re renting a proxy from us, scan the assigned port to confirm it is reachable from your location.

Why the lists are curated

A free public scanner that accepts arbitrary port ranges turns into a generic reconnaissance service. We picked three short lists that cover the questions an operator actually asks: “are my web services up,” “is mail working,” and “are the ports I usually rely on reachable.” Anything more thorough belongs on a tool you run yourself, against infrastructure you own.

Common ports

18 general-purpose ports including SSH, HTTP, HTTPS, and database services.

Web services

12 ports used by HTTP, HTTPS, common reverse proxies, and dashboard front-ends.

Mail services

7 ports used by SMTP submission, IMAP, POP3, and their TLS variants.

Frequently asked questions

Why is the list of ports fixed?
A public tool that accepts arbitrary port ranges quickly becomes a reconnaissance service against random networks. The fixed lists keep the tool useful for everyday operator checks while making it hard to misuse.
Can I scan ports inside my own network?
No. Targets that resolve to private, loopback, link-local, or reserved addresses are refused. Internal scans should run from inside the network they target.
What does “open” mean here?
It means our infrastructure was able to complete a TCP handshake to that port. The service may still reject your traffic at the application layer.
What does “closed” mean?
Our probe was either actively refused or timed out. From the outside, we cannot reliably tell which it was without sending more probes than we want to.
Will my server see this scan in its logs?
Yes. Each probe is a real TCP connection from our edge IPs. If you operate the host you’re scanning, you can confirm it on your end.
How fast is the scan?
A single scan against the curated list usually finishes in a couple of seconds. There is a per-IP rate limit, so repeated scans from the same browser are spaced out.

Need a server with reachable proxy ports?

Our datacenter and ISP plans expose stable ports with predictable reachability worldwide.

View plans