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 Kiểm Tra Kết Nối Cổng TCP
Author: Check-Host

Info Ping HTTP TCP UDP MTR DNS

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

Checked Apr 21, 2026 21:01:51 UTC |

| Check again |

Location	Result	Time	IP Address
Albania, Tirana	Connected	120.0 ms	188.93.91.194
Australia, Sydney	Connected	324.0 ms	188.93.91.194
Bosnia and Herzegovina, Novi Travnik	Connected	74.0 ms	188.93.91.194
Bulgaria, Sofia	Connected	68.0 ms	188.93.91.194
Canada, Montreal	Connected	185.0 ms	188.93.91.194
Switzerland, Bern	Connected	72.0 ms	188.93.91.194
Chile, Santiago	Connected	293.0 ms	188.93.91.194
China, Hohhot	Connected	296.0 ms	188.93.91.194
Germany, Nuernberg	Connected	78.0 ms	188.93.91.194
Germany, Frankfurt am Main	Connected	60.0 ms	188.93.91.194
Germany, Frankfurt am Main	Connected	64.0 ms	188.93.91.194
Germany, Limburg	Connected	64.0 ms	188.93.91.194
Germany, Frankfurt am Main	Connected	69.0 ms	188.93.91.194
Germany, Duesseldorf	Connected	67.0 ms	188.93.91.194
Denmark, Glostrup Municipality	Connected	12.0 ms	188.93.91.194
Spain, Bilbao	Connected	115.0 ms	188.93.91.194
Finland, Helsinki	Connected	104.0 ms	188.93.91.194
Finland, Helsinki	Connected	100.0 ms	188.93.91.194
France, Gravelines	Connected	80.0 ms	188.93.91.194
France, Paris	Connected	9.0 ms	188.93.91.194
United Kingdom, London	Connected	80.0 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	74.0 ms	188.93.91.194
Croatia, Zagreb	Connected	70.0 ms	188.93.91.194
Hungary, Budapest	Connected	15.0 ms	188.93.91.194
Indonesia, Jakarta	Connected	308.0 ms	188.93.91.194
Israel, Petach Tikwa	Connected	124.0 ms	188.93.91.194
Israel, Netanja	Connected	118.0 ms	188.93.91.194
India, New Delhi	Connected	325.0 ms	188.93.91.194
Iceland, Reykjavik (Miðborg)	Connected	114.0 ms	188.93.91.194
Italy, Como	Connected	76.0 ms	188.93.91.194
Kuwait, Kuwait City	ERROR	-	ge-tbi-9.check-host.eu
Lithuania, Pilaite	Connected	126.0 ms	188.93.91.194
Latvia, Riga	Connected	31.0 ms	188.93.91.194
Moldova, Chisinau	Connected	35.0 ms	188.93.91.194
Netherlands, Amsterdam	Connected	78.0 ms	188.93.91.194
Netherlands, Amsterdam	Connected	66.0 ms	188.93.91.194
Netherlands, Amsterdam	Connected	81.0 ms	188.93.91.194
Netherlands, Amsterdam	Connected	83.0 ms	188.93.91.194
Norway, Oslo	Connected	75.0 ms	188.93.91.194
Poland, Warsaw	Connected	20.0 ms	188.93.91.194
Romania, Bacău	Connected	91.0 ms	188.93.91.194
Romania, Bucharest	Connected	89.0 ms	188.93.91.194
Serbia, Belgrade	Connected	123.0 ms	188.93.91.194
Russia, St Petersburg	Connected	100.0 ms	188.93.91.194
Singapore, Singapore	Connected	314.0 ms	188.93.91.194
Turkey, Istanbul	Connected	101.0 ms	188.93.91.194
Taiwan, Taipei	Connected	301.0 ms	188.93.91.194
United States, Miami	Connected	202.0 ms	188.93.91.194
United States, Dallas	Connected	184.0 ms	188.93.91.194
United States, Kansas City	Connected	193.0 ms	188.93.91.194
United States, Dallas	Connected	192.0 ms	188.93.91.194
South Africa, Johannesburg	Connected	232.0 ms	188.93.91.194