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.

Informe para za-joh-virtarix.check-host.eu:80

Name: Check-Host za-joh-virtarix.check-host.eu:80 Prueba de conectividad TCP
Author: Check-Host

Info Ping HTTP TCP UDP MTR DNS

Comprobar TCP za-joh-virtarix.check-host.eu:80

Comprobado Jul 21, 2026 17:09:02 UTC |

| Comprobar de nuevo |

Ubicación	Resultado	Tiempo	Dirección IP
Albania, Tirana	ERROR	-	102.208.217.202
Australia, Sydney	ERROR	-	102.208.217.202
Bosnia and Herzegovina, Novi Travnik	ERROR	-	102.208.217.202
Bulgaria, Sofia	ERROR	-	102.208.217.202
Brazil, São Paulo	ERROR	-	102.208.217.202
Canada, Montreal	ERROR	-	102.208.217.202
Switzerland, Bern	ERROR	-	102.208.217.202
Switzerland, Zurich	ERROR	-	102.208.217.202
Chile, Santiago	ERROR	-	102.208.217.202
China, Hohhot	ERROR	-	102.208.217.202
Germany, Nuernberg	ERROR	-	102.208.217.202
Germany, Frankfurt am Main	ERROR	-	102.208.217.202
Germany, Limburg	ERROR	-	102.208.217.202
Germany, Frankfurt am Main	ERROR	-	102.208.217.202
Germany, Frankfurt am Main	ERROR	-	102.208.217.202
Germany, Frankfurt am Main	ERROR	-	102.208.217.202
Germany, Koblenz	ERROR	-	102.208.217.202
Denmark, Glostrup Municipality	ERROR	-	-
Spain, Bilbao	ERROR	-	102.208.217.202
Spain, Barcelona	ERROR	-	102.208.217.202
Finland, Helsinki	ERROR	-	102.208.217.202
Finland, Helsinki	ERROR	-	102.208.217.202
France, Gravelines	ERROR	-	102.208.217.202
France, Paris	ERROR	-	102.208.217.202
United Kingdom, London	ERROR	-	102.208.217.202
Georgia, Tbilisi	ERROR	-	za-joh-virtarix.check-host.eu
Hong Kong, Hong Kong	ERROR	-	102.208.217.202
Croatia, Zagreb	ERROR	-	102.208.217.202
Hungary, Budapest	ERROR	-	102.208.217.202
Israel, Petach Tikwa	ERROR	-	102.208.217.202
Israel, Netanja	ERROR	-	102.208.217.202
India, New Delhi	ERROR	-	102.208.217.202
Iceland, Reykjavik (Miðborg)	ERROR	-	102.208.217.202
Italy, Como	ERROR	-	102.208.217.202
South Korea, Seoul	ERROR	-	102.208.217.202
Lithuania, Pilaite	ERROR	-	102.208.217.202
Latvia, Riga	ERROR	-	102.208.217.202
Moldova, Chisinau	ERROR	-	102.208.217.202
Netherlands, Amsterdam	ERROR	-	102.208.217.202
Netherlands, Amsterdam	ERROR	-	102.208.217.202
Netherlands, Amsterdam	ERROR	-	102.208.217.202
Netherlands, Amsterdam	ERROR	-	102.208.217.202
Netherlands, Eygelshoven	ERROR	-	102.208.217.202
Norway, Oslo	ERROR	-	102.208.217.202
Poland, Warsaw	ERROR	-	102.208.217.202
Romania, Bacău	ERROR	-	102.208.217.202
Romania, Bucharest	ERROR	-	102.208.217.202
Serbia, Belgrade	ERROR	-	102.208.217.202
Russia, Moscow	ERROR	-	102.208.217.202
Singapore, Singapore	ERROR	-	102.208.217.202
Tor, Onion	ERROR	-	za-joh-virtarix.check-host.eu
Tor, Onion	ERROR	-	za-joh-virtarix.check-host.eu
Tor, Onion	ERROR	-	za-joh-virtarix.check-host.eu
Turkey, Istanbul	ERROR	-	102.208.217.202
Turkey, Istanbul	ERROR	-	102.208.217.202
Taiwan, Taipei	ERROR	-	102.208.217.202
Ukraine, Khmelnytskyi	ERROR	-	102.208.217.202
United States, Dallas	ERROR	-	102.208.217.202
United States, Dallas	ERROR	-	102.208.217.202
United States, Los Angeles	ERROR	-	102.208.217.202
United States, Houston	ERROR	-	102.208.217.202
United States, Miami	ERROR	-	102.208.217.202
South Africa, Johannesburg	ERROR	-	102.208.217.202
South Africa, Johannesburg	ERROR	-	102.208.217.202