Open Port Scanner

Scan your public IP for dangerous open ports — RDP, SMB, and more. See what attackers see before they do.

Only your own IP is scanned — this tool cannot be used to scan others

Scans 15 common ports: FTP, SSH, Telnet, SMTP, HTTP, POP3, RPC, HTTPS, SMB, MSSQL, MySQL, RDP, VNC, HTTP-Alt, HTTPS-Alt.
The scan runs from my server against your public IP. May take up to 25 seconds.
Using a VPN or Tor? The scan will test the VPN server's or Tor exit node's IP — not your home connection. Disable it first for an accurate result.

How the Scan Works

Unlike browser-based tools that are limited by security restrictions, this scanner runs server-side: my server attempts a TCP connection to each port on your public IP and records whether the port is open, closed, or filtered by a firewall.

Three possible results for each port:

OPEN	A service is listening and accepted the connection. The port is reachable from the internet.
CLOSED	The port responded but refused the connection. No service running, but the port is reachable.
FILTERED	No response within the timeout. A firewall is likely dropping packets silently.

The scan only covers your public-facing IP — the address the internet sees. Devices behind your router are not individually exposed unless you have port forwarding rules configured.

Why Open Ports Are a Risk

Every open port is a potential entry point. Automated scanners operated by attackers continuously sweep the entire IPv4 address space, probing for open ports on every public IP. When they find one, they attempt known exploits and credential attacks within minutes.

RDP (port 3389) is the #1 ransomware entry point in the US. On today's internet, an exposed RDP port is like leaving your front door wide open in a bad neighborhood — attackers will find it and start knocking within minutes. US small businesses and home offices running Windows Remote Desktop directly on the internet are primary targets.

The risk varies by port. A web server intentionally running HTTP/HTTPS on ports 80 and 443 is expected. But an exposed database port (3306, 1433) or remote desktop port (3389, 5900) on a home or small business connection is almost always a misconfiguration — and a serious one.

What to Do If a Dangerous Port Is Open

Close the port if you don't need the service

If you don't know why a port is open, it shouldn't be. Disable the service or block the port in your firewall. On Windows, check Services and Windows Defender Firewall. On a router, check port forwarding rules.

Move remote access behind a VPN

If you need RDP or SSH access to your machine, don't expose the port directly. Put it behind a VPN — connect to the VPN first, then use remote access. This removes the service from public view entirely.

Restrict access by IP address

If you must keep a port open, limit access to specific trusted IP addresses. For example, allow RDP only from your office IP. Most modern routers and cloud firewalls (like AWS or Azure) support IP allowlisting.

Change default ports and use strong credentials

If closing or hiding the port isn't possible, move the service to a non-standard port and ensure you're using complex, unique credentials with account lockout enabled to block brute-force attempts. While this won't stop a determined attacker, it drastically reduces the success of automated botnets and stops most "spray-and-pray" attacks. Security through obscurity is not enough — a weak password is still a back door.

The Verdict: Closed Should Be Your Default

For most home users and small businesses, no ports should be open unless you are explicitly running a public service. If your scan shows RDP, SMB, Telnet, or any database port as open — close it immediately.

Final step: check your router's UPnP and port forwarding settings, your firewall rules, and any remote access software you may have installed. Disable UPnP on your router to prevent devices from automatically opening ports without your knowledge. After making changes, re-run this scan to verify your security.

Also Check Your Email for Breaches

Frequently Asked Questions

What is a port and why does it matter for security?

Think of your IP address like the street address of a large apartment building. Ports are the individual doors to the apartments. Some doors (like 80 or 443) are meant for the public, but others (like 3389 for RDP) should be locked tight. An "open" port is an unlocked door that an attacker can use to walk right into your network.

Are open ports dangerous?

It depends on which port is open and whether the service behind it is up to date and properly secured. Some open ports are intentional and necessary (for example, port 443 if you're running a web server). Others — like RDP (3389), Telnet (23), or outdated FTP (21) — on residential connections are almost never needed and significantly increase your attack surface. Unpatched services on open ports are one of the most common initial access vectors for attackers.

Which open ports are the most dangerous?

The highest-risk open ports on residential or small business connections are: 3389 (RDP) — heavily targeted for ransomware; exposed RDP ports are typically found by automated scanners within minutes of going live; 22 (SSH) — constant brute-force attacks if exposed without key-based auth; 23 (Telnet) — unencrypted, should never be exposed; 445 (SMB) — used in WannaCry and similar worm attacks; 3306 (MySQL) and 5432 (PostgreSQL) — databases should never be publicly accessible.

How do I close an open port?

Open ports are controlled by your router firewall and the services running on your device. In your router admin panel, check for port forwarding rules and remove any you didn't intentionally create. Also check if UPnP (Universal Plug and Play) is enabled — this feature allows games or apps to open ports automatically without your knowledge, and is one of the most common reasons ports appear open unexpectedly on home routers. On Windows, go to Windows Defender Firewall → Advanced Settings and block inbound rules for the port. On Linux, use ufw deny [port] or iptables rules. If a service you're not using is listening on a port, disable or uninstall that service entirely.

I'm working from home — do I need any open ports?

Almost never. Most modern VPNs and remote-work tools (like Zoom, Teams, or Slack) do not require you to open ports on your router — they initiate outbound connections that firewalls allow through automatically. If your company asks you to open port 3389 for remote desktop, suggest using a corporate VPN instead. Exposing RDP directly on a home connection is a significant risk and a common ransomware entry point. When in doubt, assume closed is correct.

Does this scanner check all 65,535 ports?

This tool scans the most commonly exploited and security-relevant ports rather than all 65,535. A full port scan of every port would take significantly longer and is rarely necessary for most users. The scanned ports cover the highest-risk services including remote access, file sharing, database, and legacy protocols. For comprehensive network auditing, dedicated tools like Nmap are more appropriate.