Open Port Checker

Test whether a TCP port on your public IP address is open and reachable from the internet. Ideal for checking port forwarding for games, cameras, servers and VPNs.

21 FTP22 SSH25 SMTP53 DNS80 HTTP110 POP3143 IMAP443 HTTPS445 SMB587 SMTP Submission993 IMAPS1194 OpenVPN3306 MySQL3389 Remote Desktop5432 PostgreSQL5900 VNC8080 HTTP Alt8443 HTTPS Alt25565 Minecraft27015 Steam / Source32400 Plex51820 WireGuard (UDP)
Port 110 is closed or filtered on 216.73.216.48No response within 4 seconds. A firewall, your router or your ISP is probably dropping the traffic.

How the open port checker works

When you press Check, our server tries to open a TCP connection to your own public IP address on the port you chose, just like a player joining your game server or an app connecting to your camera would. There are three possible results:

  • Open: the connection succeeded. Port forwarding and firewalls are configured correctly and a program is listening.
  • Closed: the connection was refused. Traffic reaches the device, but no application is listening on that port.
  • Filtered: no reply at all. A firewall is silently dropping the traffic, the port is not forwarded, or your ISP blocks it.

For security and to prevent abuse, this tool only tests the IP address you are connecting from. It cannot be used to scan other people's networks.

How to open a port (port forwarding)

  1. Give the device running the service a fixed local IP, for example via a DHCP reservation in your router.
  2. Log in to your router, usually at 192.168.1.1 or 192.168.0.1, and find Port Forwarding, Virtual Server or NAT.
  3. Forward the external port (TCP) to the device's local IP and port.
  4. Allow the program through the device's firewall (Windows Defender Firewall, macOS firewall or ufw).
  5. Make sure the program is running, then test again here.

Why a port still shows closed

  • Carrier-grade NAT (CGNAT): if your router's WAN address is in 100.64.0.0/10 or a private range, your ISP shares one public IP among many customers and inbound connections cannot reach you. Ask your ISP for a public IPv4 address, or use IPv6.
  • ISP blocking: many residential ISPs block inbound ports 25, 80, 135–139 and 445.
  • Double NAT: an ISP modem and your own router both doing NAT. Put the modem in bridge mode or forward on both.
  • UDP-only services such as WireGuard (51820/udp) cannot be confirmed by a TCP test.

See the common network ports reference for what runs on each port.

Security tip: every open port is a door into your network. Never expose Remote Desktop (3389), SMB (445) or database ports directly; use a VPN instead.

Frequently asked questions

Can I check UDP ports?

Not reliably. UDP is connectionless, so a closed UDP port and a filtered one look the same from outside.

Why does my IPv6 port check fail?

Our checker connects over IPv4. IPv6 devices also need their own firewall rule, because IPv6 does not use NAT.

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