OnMyPort
My IP Ports

Open Port Checker & Port Forwarding Test

Test router port forwarding and external TCP port reachability instantly without bloat or ads.

Port Scanner
Your Public IP
Reset to my IP
1–65535
Quick:
Recent Probes 0

No recent scans recorded.

Target hosts and tested ports will appear here automatically for fast 1-click re-testing.

Auto-prunes oldest probes beyond 10 entries (FIFO)

TCP Port Diagnosis: Filtered vs Closed vs Open

Understand port probe outcomes and quick fixes before changing router settings.

OPEN SYN-ACK

Handshake Successful

Your host responded to the TCP probe. The port is open and routing traffic normally.

  • Port forward rule is active.
  • App daemon is listening.
  • Reachable from public internet.
✓ Ready for traffic
CLOSED RST Packet

Host Reached, No Service

Packets reached your device, but the OS rejected the connection (TCP RST).

  • Service/server is not running.
  • App listening on 127.0.0.1 instead of 0.0.0.0.
  • Router forward points to wrong internal IP.
Fix: Bind service to 0.0.0.0
FILTERED Timeout (2s)

Packet Dropped / Timeout

No response within 2000ms. Packets were blocked or discarded on route.

  • Windows Defender / UFW firewall blocking.
  • Missing router port forward rule.
  • ISP blocks port or uses CGNAT.
Fix: Check Firewall & Router NAT
CGNAT Detection & Fix

If ports show FILTERED despite correct rules, your ISP likely uses Carrier-Grade NAT (WAN IP 100.64.0.0/10). Standard port forwarding won't work without a static IP or Cloudflare/Tailscale tunnel.

Router Port Collisions (80 & 443)

Testing ports 80 or 443 on home routers can fail because the router reserves them for its own web UI. Remap external port (e.g., forward external 8443 to internal 443) and assign a static LAN DHCP reservation.

FREQUENTLY ASKED QUESTIONS

Frequently Asked Questions & Port Diagnostics

Everything you need to know about checking open ports, router port forwarding, and network security.

How do I check my port?

Enter your public IP (auto-detected above) and the target port number (e.g. 25565, 80, 443, 22), then click "Check Port". Our edge server sends an immediate TCP SYN packet. If your router forwards the packet and your application responds with SYN-ACK, the port is OPEN and accessible to the internet.

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How can I check if port 443 is open?

To test port 443 (HTTPS), keep your web server running, type 443 in the Port field, and click "Check Port". If it shows CLOSED or FILTERED, confirm your SSL web daemon (Nginx, Apache, Caddy, or IIS) is bound to 0.0.0.0 and your router does not reserve 443 for its remote admin panel.

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Can you see me check my port?

No. onmyport.com operates with a strict zero-logging policy. Probes are executed strictly in memory to perform the TCP handshake and verify reachability. We do not store your IP address, target ports, or scan history on any database or persistent log.

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How can I check my IP port?

Your external WAN IP is automatically detected when you open onmyport.com. Simply choose your port number or select a quick preset (such as Minecraft 25565, RDP 3389, or SSH 22) and hit "Check Port". You can also test remote domains or secondary servers anytime.

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How to check open ports in CMD and PowerShell?

In Windows Command Prompt (CMD), run "netstat -ano | findstr :<PORT>" to see if an application is LISTENING locally. In PowerShell, run "Test-NetConnection 127.0.0.1 -Port <PORT>" to verify socket connectivity and obtain "TcpTestSucceeded : True".

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How does a UDP port checker work online?

Unlike TCP which uses a 3-way handshake (SYN, SYN-ACK, ACK), UDP is connectionless and does not respond unless the specific application protocol answers with valid payload. Most online UDP port scanners guess or rely on ICMP "Port Unreachable" packets, which routers routinely drop. For reliable UDP verification (DNS 53, WireGuard 51820), local socket testing or bidirectional protocol testing is required.

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How to test port forwarding on routers (TP-Link, Asus, Netgear, ISP)?

Log into your router (e.g. 192.168.1.1 or 192.168.0.1), navigate to Port Forwarding / Virtual Server, and forward the external port (e.g. 25565) to your PC's internal static IP. Ensure Windows Defender Firewall allows inbound TCP traffic, then test your public IP on onmyport.com. If still FILTERED, verify your ISP does not use CGNAT.

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Why does port checker show filtered instead of closed?

A FILTERED result means your TCP SYN packet was silently dropped without any acknowledgment—typically caused by Windows Defender Firewall, an upstream router without a forwarding rule, or ISP CGNAT. In contrast, a CLOSED result proves your host is reachable, but the target operating system replied with a TCP RST packet because no application is listening on that port or it is restricted to 127.0.0.1.

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Need step-by-step setup guides?

Learn how to port forward Minecraft 25565, check listening ports in PowerShell, or bypass CGNAT with zero-trust tunnels.

Browse All Guides