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 50+ 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 ge-tbi-9.check-host.eu:80

Name: Check-Host ge-tbi-9.check-host.eu:80 TCP Port Connectivity Test
Author: Check-Host

Info Ping HTTP TCP UDP MTR DNS

Check TCP ge-tbi-9.check-host.eu:80

Checked Apr 22, 2026 13:47:41 UTC |

| Check again |

Location	Result	Time	IP Address
Albania, Tirana	Connected	114.0 ms	188.93.91.194
Australia, Sydney	Connected	316.0 ms	188.93.91.194
Bosnia and Herzegovina, Novi Travnik	Connected	74.0 ms	188.93.91.194
Bulgaria, Sofia	Connected	69.0 ms	188.93.91.194
Canada, Montreal	Connected	151.0 ms	188.93.91.194
Switzerland, Bern	Connected	72.0 ms	188.93.91.194
Chile, Santiago	Connected	291.0 ms	188.93.91.194
China, Hohhot	Connected	294.0 ms	188.93.91.194
Germany, Nuernberg	Connected	78.0 ms	188.93.91.194
Germany, Frankfurt am Main	Connected	59.0 ms	188.93.91.194
Germany, Frankfurt am Main	Connected	58.0 ms	188.93.91.194
Germany, Limburg	Connected	58.0 ms	188.93.91.194
Germany, Frankfurt am Main	Connected	64.0 ms	188.93.91.194
Germany, Duesseldorf	Connected	80.0 ms	188.93.91.194
Denmark, Glostrup Municipality	Connected	12.0 ms	188.93.91.194
Spain, Bilbao	Connected	112.0 ms	188.93.91.194
Finland, Helsinki	Connected	120.0 ms	188.93.91.194
Finland, Helsinki	Connected	94.0 ms	188.93.91.194
France, Gravelines	Connected	81.0 ms	188.93.91.194
France, Paris	Connected	9.0 ms	188.93.91.194
United Kingdom, London	Connected	75.0 ms	188.93.91.194
Georgia, Tbilisi	ERROR	-	ge-tbi-9.check-host.eu
Greece, Athens	ERROR	-	ge-tbi-9.check-host.eu
Hong Kong, Hong Kong	Connected	75.0 ms	188.93.91.194
Croatia, Zagreb	Connected	99.0 ms	188.93.91.194
Hungary, Budapest	Connected	15.0 ms	188.93.91.194
Indonesia, Jakarta	Connected	304.0 ms	188.93.91.194
Israel, Petach Tikwa	Connected	121.0 ms	188.93.91.194
Israel, Netanja	Connected	109.0 ms	188.93.91.194
India, New Delhi	Connected	319.0 ms	188.93.91.194
Iceland, Reykjavik (Miðborg)	Connected	115.0 ms	188.93.91.194
Italy, Como	Connected	77.0 ms	188.93.91.194
Kuwait, Kuwait City	ERROR	-	ge-tbi-9.check-host.eu
Lithuania, Pilaite	Connected	115.0 ms	188.93.91.194
Latvia, Riga	Connected	31.0 ms	188.93.91.194
Moldova, Chisinau	Connected	36.0 ms	188.93.91.194
Netherlands, Amsterdam	Connected	75.0 ms	188.93.91.194
Netherlands, Amsterdam	Connected	72.0 ms	188.93.91.194
Netherlands, Amsterdam	Connected	81.0 ms	188.93.91.194
Netherlands, Amsterdam	Connected	79.0 ms	188.93.91.194
Norway, Oslo	Connected	81.0 ms	188.93.91.194
Poland, Warsaw	Connected	21.0 ms	188.93.91.194
Romania, Bacău	Connected	101.0 ms	188.93.91.194
Romania, Bucharest	Connected	83.0 ms	188.93.91.194
Serbia, Belgrade	Connected	34.0 ms	188.93.91.194
Russia, St Petersburg	Connected	104.0 ms	188.93.91.194
Singapore, Singapore	Connected	294.0 ms	188.93.91.194
Turkey, Istanbul	Connected	101.0 ms	188.93.91.194
Taiwan, Taipei	Connected	309.0 ms	188.93.91.194
United States, Miami	Connected	185.0 ms	188.93.91.194
United States, Dallas	Connected	201.0 ms	188.93.91.194
United States, Kansas City	Connected	228.0 ms	188.93.91.194
United States, Dallas	Connected	191.0 ms	188.93.91.194
South Africa, Johannesburg	Connected	219.0 ms	188.93.91.194