Open Port Check Tool – Test Multiple TCP and UDP Ports
Test up to 20 ports on any public IP or hostname. Verify port forwarding for web servers, remote access, and CCTV systems.
Common ports - click to test
| Port | Protocol | Service |
|---|---|---|
| 80 | HTTP | Web server |
| 443 | HTTPS | Web server (SSL) |
| 554 | RTSP | Camera video stream |
| 8000 | HTTP | Hikvision DVR/NVR |
| 8080 | HTTP | Alternate web / proxy |
| 37777 | TCP | Dahua DVR/NVR |
| 34567 | TCP | XM / Provision / Annke |
| 8443 | HTTPS | HTTPS alternate |
| 22 | SSH | Secure shell |
| 3389 | RDP | Windows Remote Desktop |
| 21 | FTP | File transfer |
How to Check Whether a Port Is Open
The check runs from our server on the public internet, the same route a visitor or a remote app would take. That is the only vantage point that can tell you whether a port is reachable from outside your own network.
- 1Enter the public IP address or DDNS hostname you want to reach.
- 2Pick TCP or UDP, then type up to 20 ports separated by commas.
- 3Run the check and read each port on its own line — Open, Closed, or Open | Filtered, with the response time.
Test Port Forwarding from Outside Your Network
A forwarding rule only works when every step of the path allows the traffic through. Testing from a device on the same network proves nothing, because that traffic never leaves your router.
- Test your public IP or DDNS hostname, never a 192.168.x.x or 10.x.x.x address.
- The service behind the port has to be running and listening while you test.
- The router rule must point at the right internal IP, which can change after a reboot.
- Both the router firewall and the firewall on the device itself must allow inbound traffic.
- If your ISP uses CGNAT, the port stays unreachable no matter how the router is configured.
Check CCTV, DVR, and NVR Ports
Remote camera access is the most common reason a port check is run at all. A recorder usually needs more than one port reachable — a web port for the interface, a streaming port for the video, and often a vendor control port for the mobile app — so test them in one run instead of one at a time.
RTSP Port 554
Port 554 carries the video stream itself on most IP cameras and recorders. If the web interface loads remotely but live video never starts, 554 is usually the port that was never forwarded. Some devices move RTSP elsewhere, so confirm the value in the device settings first.
Hikvision Port 8000
Hikvision devices commonly use 8000 for the desktop and mobile client service, alongside 80 for the web interface. Installers change both often, so read the current values from the device rather than assuming the defaults.
Dahua Port 37777
Dahua recorders commonly use 37777 for their control and streaming protocol. XM-based units sold under names such as Provision or Annke commonly use 34567. Defaults vary by firmware, so check what your unit is actually configured with.
What Open, Closed, and Open | Filtered Mean
Each result describes what our server observed at the moment of the test, not a permanent property of your connection.
TCP Results
Open means the TCP handshake completed: something accepted the connection on that port. Closed means the connection did not complete within the timeout — either nothing is listening, or something along the path dropped it.
UDP Results and Their Limitations
UDP has no handshake, so the answer is weaker evidence than TCP. Open means the service actually replied to our probe. Open | Filtered means nothing replied and no rejection came back either — the port may be open behind a service that ignores unknown packets, or silently filtered on the way. Closed means the host reported that nothing is listening there.
Why Is My Port Still Closed?
Work down this list in order — most failed checks stop at one of the first three.
- The service is not running, or it listens on a different port than the one you forwarded.
- The rule points at an internal IP the device no longer holds; give it a static or reserved address.
- A firewall on the device itself — Windows Defender, iptables, or the camera's own access rules — drops the connection.
- The router sits behind a second router, so the rule has to exist on both (double NAT).
- The ISP hands out a shared address through CGNAT, and inbound ports cannot be opened at all.
- The ISP blocks that port; 25, 80 and 445 are the usual ones on residential lines.
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Port Checker FAQ
What does Open mean in an open port check?
Open means our server reached your target IP and completed a TCP connection on that port. It confirms that the path is reachable from the internet at test time.
Why can a port show Closed even after port forwarding?
Closed can happen if the service is not running, the wrong internal IP is mapped, firewall rules block inbound traffic, or your ISP uses CGNAT.
Do I test my local LAN IP or public IP?
For remote access checks, test your public IP or DDNS hostname. Testing a private LAN IP only validates local network routing, not internet reachability.
Can I check multiple ports at once?
Yes. Enter up to 20 ports separated by commas and every one of them is tested in the same run, each with its own result and response time.
Can a UDP port checker confirm that a port is open?
Only when the service answers. For well-known UDP services this tool sends a real request and reports Open on a reply; when nothing answers, the result is reported honestly as Open | Filtered rather than as Open.
Check ports faster on mobile
FastDDNS mobile app includes built-in Port Check, LAN Scan, and WAN IP detection for faster troubleshooting on-site.
