How do I check if a TCP port is open online?

Enter your server's IP address or domain followed by a colon and the port number (e.g. 1.1.1.1:80 or example.com:443) and run a TCP check. The tool attempts a TCP handshake from 65+ global nodes and reports whether each connection succeeded, was refused, or timed out.

What is the difference between a port being refused versus timing out?

A refused connection (TCP RST) means the port is actively closed — the server replied to reject the connection. A timeout means no reply was received at all, which typically indicates a firewall is silently dropping packets before they reach the server or application.

Which TCP ports can I test?

Any valid TCP port from 1 to 65535. Common examples include port 80 (HTTP), 443 (HTTPS), 22 (SSH), 25 (SMTP), 3306 (MySQL), 5432 (PostgreSQL), and 3389 (RDP). No login or special permissions required — the check only verifies whether the TCP handshake completes.

My port is open locally but fails from external nodes — why?

If a port works locally but fails from external nodes, something between the internet and your server is blocking it — commonly a cloud security group, iptables rule, upstream ISP filter, or geoblocking policy. Running the check from multiple regions helps identify whether the block is global or specific to certain countries or ASNs.

Report for 8.8.8.8:53

Info Ping HTTP TCP UDP MTR DNS

Check TCP 8.8.8.8:53

Checked Oct 23, 2026 04:26:19 UTC |

| Check again |

Location	Result	Time	IP Address
Australia, Sydney	Connected	1.0 ms	8.8.8.8
Bosnia and Herzegovina, Novi Travnik	Connected	23.0 ms	8.8.8.8
Bulgaria, Sofia	Connected	6.0 ms	8.8.8.8
Canada, Montreal	Connected	1.0 ms	8.8.8.8
Switzerland, Bern	Connected	1.0 ms	8.8.8.8
Switzerland, Zurich	Connected	27.0 ms	8.8.8.8
China, Hohhot	Connected	200.0 ms	8.8.8.8
Cyprus, Larnaca	Connected	9.0 ms	8.8.8.8
Germany, Nuernberg	Connected	9.0 ms	8.8.8.8
Germany, Frankfurt am Main	Connected	0.0 ms	8.8.8.8
Germany, Frankfurt am Main	Connected	0.0 ms	8.8.8.8
Germany, Frankfurt am Main	Connected	2.0 ms	8.8.8.8
Germany, Koblenz	Connected	16.0 ms	8.8.8.8
Germany, Frankfurt am Main	Connected	4.0 ms	8.8.8.8
Denmark, Glostrup Municipality	Connected	71.0 ms	8.8.8.8
Spain, Bilbao	Connected	37.0 ms	8.8.8.8
Spain, Barcelona	Connected	21.0 ms	8.8.8.8
Finland, Helsinki	Connected	5.0 ms	8.8.8.8
Finland, Helsinki	Connected	11.0 ms	8.8.8.8
France, Gravelines	Connected	4.0 ms	8.8.8.8
France, Paris	Connected	61.0 ms	8.8.8.8
United Kingdom, London	Connected	8.0 ms	8.8.8.8
Hong Kong, Hong Kong	Connected	2.0 ms	8.8.8.8
Croatia, Zagreb	Connected	24.0 ms	8.8.8.8
Hungary, Budapest	Connected	44.0 ms	8.8.8.8
Israel, Petach Tikwa	Connected	3.0 ms	8.8.8.8
Israel, Netanja	Connected	2.0 ms	8.8.8.8
Iran, Tehran	Connected	0.0 ms	8.8.8.8
Iran, Tehran	Connected	1.0 ms	8.8.8.8
Iceland, Reykjavik (Miðborg)	Connected	22.0 ms	8.8.8.8
Italy, Como	Connected	1.0 ms	8.8.8.8
Japan, Tokyo	Connected	1.0 ms	8.8.8.8
South Korea, Seoul	Connected	29.0 ms	8.8.8.8
Kazakhstan, Almaty	Connected	88.0 ms	8.8.8.8
Lithuania, Pilaite	Connected	84.0 ms	8.8.8.8
Latvia, Riga	Connected	63.0 ms	8.8.8.8
Netherlands, Amsterdam	Connected	1.0 ms	8.8.8.8
Netherlands, Amsterdam	Connected	3.0 ms	8.8.8.8
Netherlands, Amsterdam	Connected	2.0 ms	8.8.8.8
Netherlands, Amsterdam	Connected	1.0 ms	8.8.8.8
Netherlands, Eygelshoven	Connected	4.0 ms	8.8.8.8
Norway, Oslo	Connected	32.0 ms	8.8.8.8
Poland, Warsaw	Connected	35.0 ms	8.8.8.8
Romania, Bacău	Connected	39.0 ms	8.8.8.8
Romania, Bucharest	Connected	8.0 ms	8.8.8.8
Serbia, Belgrade	Connected	12.0 ms	8.8.8.8
Russia, Moscow	Connected	26.0 ms	8.8.8.8
Singapore, Singapore	Connected	2.0 ms	8.8.8.8
Tor, Onion	ERROR	-	8.8.8.8
Tor, Onion	ERROR	-	8.8.8.8
Tor, Onion	ERROR	-	8.8.8.8
Turkey, Istanbul	Connected	12.0 ms	8.8.8.8
Ukraine, Khmelnytskyi	Connected	27.0 ms	8.8.8.8
United States, Dallas	Connected	10.0 ms	8.8.8.8
United States, Los Angeles	Connected	29.0 ms	8.8.8.8
United States, Houston	Connected	12.0 ms	8.8.8.8
United States, Miami	Connected	1.0 ms	8.8.8.8
South Africa, Johannesburg	Connected	2.0 ms	8.8.8.8