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 Test łączności TCP
Author: Check-Host

Info Ping HTTP TCP UDP MTR DNS

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

Checked Apr 21, 2026 13:53:16 UTC |

| Check again |

Location	Result	Time	IP Address
Albania, Tirana	Connected	182.0 ms	188.93.91.194
Australia, Sydney	Connected	317.0 ms	188.93.91.194
Bosnia and Herzegovina, Novi Travnik	Connected	80.0 ms	188.93.91.194
Bulgaria, Sofia	Connected	68.0 ms	188.93.91.194
Canada, Montreal	Connected	183.0 ms	188.93.91.194
Switzerland, Bern	Connected	65.0 ms	188.93.91.194
Chile, Santiago	Connected	293.0 ms	188.93.91.194
China, Hohhot	ERROR	-	188.93.91.194
Germany, Nuernberg	Connected	73.0 ms	188.93.91.194
Germany, Frankfurt am Main	Connected	59.0 ms	188.93.91.194
Germany, Frankfurt am Main	Connected	64.0 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	113.0 ms	188.93.91.194
Finland, Helsinki	Connected	122.0 ms	188.93.91.194
Finland, Helsinki	Connected	92.0 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	77.0 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	68.0 ms	188.93.91.194
Croatia, Zagreb	Connected	231.0 ms	188.93.91.194
Hungary, Budapest	Connected	40.0 ms	188.93.91.194
Indonesia, Jakarta	Connected	307.0 ms	188.93.91.194
Israel, Petach Tikwa	Connected	130.0 ms	188.93.91.194
Israel, Netanja	Connected	121.0 ms	188.93.91.194
India, New Delhi	Connected	317.0 ms	188.93.91.194
Iceland, Reykjavik (Miðborg)	Connected	114.0 ms	188.93.91.194
Italy, Como	Connected	72.0 ms	188.93.91.194
Kuwait, Kuwait City	ERROR	-	ge-tbi-9.check-host.eu
Lithuania, Pilaite	Connected	122.0 ms	188.93.91.194
Latvia, Riga	Connected	107.0 ms	188.93.91.194
Moldova, Chisinau	Connected	126.0 ms	188.93.91.194
Netherlands, Amsterdam	Connected	78.0 ms	188.93.91.194
Netherlands, Amsterdam	Connected	78.0 ms	188.93.91.194
Netherlands, Amsterdam	Connected	81.0 ms	188.93.91.194
Netherlands, Amsterdam	Connected	77.0 ms	188.93.91.194
Norway, Oslo	Connected	75.0 ms	188.93.91.194
Poland, Warsaw	Connected	15.0 ms	188.93.91.194
Romania, Bacău	Connected	91.0 ms	188.93.91.194
Romania, Bucharest	Connected	90.0 ms	188.93.91.194
Serbia, Belgrade	Connected	110.0 ms	188.93.91.194
Russia, St Petersburg	Connected	98.0 ms	188.93.91.194
Singapore, Singapore	Connected	296.0 ms	188.93.91.194
Turkey, Istanbul	Connected	121.0 ms	188.93.91.194
Taiwan, Taipei	Connected	312.0 ms	188.93.91.194
United States, Miami	Connected	193.0 ms	188.93.91.194
United States, Dallas	Connected	186.0 ms	188.93.91.194
United States, Kansas City	Connected	210.0 ms	188.93.91.194
United States, Dallas	Connected	188.0 ms	188.93.91.194
South Africa, Johannesburg	Connected	229.0 ms	188.93.91.194