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.

sg-sin-fdc.check-host.eu:80 のレポート

Name: Check-Host sg-sin-fdc.check-host.eu:80 TCP ポート疎通テスト
Author: Check-Host

Info Ping HTTP TCP UDP MTR DNS

TCP チェック sg-sin-fdc.check-host.eu:80

Apr 22, 2026 13:44:09 UTC に確認 |

| 再チェック |

拠点	結果	応答時間	IP アドレス
Albania, Tirana	ERROR	-	67.159.52.132
Australia, Sydney	ERROR	-	67.159.52.132
Bosnia and Herzegovina, Novi Travnik	ERROR	-	67.159.52.132
Bulgaria, Sofia	ERROR	-	67.159.52.132
Canada, Montreal	ERROR	-	67.159.52.132
Switzerland, Bern	ERROR	-	67.159.52.132
Chile, Santiago	ERROR	-	67.159.52.132
China, Hohhot	ERROR	-	67.159.52.132
Germany, Nuernberg	ERROR	-	67.159.52.132
Germany, Frankfurt am Main	ERROR	-	67.159.52.132
Germany, Frankfurt am Main	ERROR	-	67.159.52.132
Germany, Limburg	ERROR	-	67.159.52.132
Germany, Frankfurt am Main	ERROR	-	67.159.52.132
Germany, Duesseldorf	ERROR	-	67.159.52.132
Denmark, Glostrup Municipality	Connected	51.0 ms	67.159.52.132
Spain, Bilbao	ERROR	-	67.159.52.132
Finland, Helsinki	ERROR	-	67.159.52.132
Finland, Helsinki	ERROR	-	67.159.52.132
France, Gravelines	ERROR	-	67.159.52.132
France, Paris	Connected	17.0 ms	67.159.52.132
United Kingdom, London	ERROR	-	67.159.52.132
Georgia, Tbilisi	ERROR	-	sg-sin-fdc.check-host.eu
Greece, Athens	ERROR	-	sg-sin-fdc.check-host.eu
Hong Kong, Hong Kong	ERROR	-	67.159.52.132
Croatia, Zagreb	ERROR	-	67.159.52.132
Hungary, Budapest	Connected	35.0 ms	67.159.52.132
Indonesia, Jakarta	ERROR	-	67.159.52.132
Israel, Petach Tikwa	ERROR	-	67.159.52.132
Israel, Netanja	ERROR	-	67.159.52.132
India, New Delhi	ERROR	-	67.159.52.132
Iceland, Reykjavik (Miðborg)	ERROR	-	67.159.52.132
Italy, Como	ERROR	-	67.159.52.132
Kuwait, Kuwait City	ERROR	-	sg-sin-fdc.check-host.eu
Lithuania, Pilaite	ERROR	-	67.159.52.132
Latvia, Riga	Connected	62.0 ms	67.159.52.132
Moldova, Chisinau	Connected	36.0 ms	67.159.52.132
Netherlands, Amsterdam	ERROR	-	67.159.52.132
Netherlands, Amsterdam	ERROR	-	67.159.52.132
Netherlands, Amsterdam	ERROR	-	67.159.52.132
Netherlands, Amsterdam	ERROR	-	67.159.52.132
Norway, Oslo	ERROR	-	67.159.52.132
Poland, Warsaw	Connected	17.0 ms	67.159.52.132
Romania, Bacău	ERROR	-	67.159.52.132
Romania, Bucharest	ERROR	-	67.159.52.132
Serbia, Belgrade	Connected	59.0 ms	67.159.52.132
Russia, St Petersburg	ERROR	-	67.159.52.132
Singapore, Singapore	ERROR	-	67.159.52.132
Turkey, Istanbul	ERROR	-	67.159.52.132
Taiwan, Taipei	ERROR	-	67.159.52.132
United States, Miami	ERROR	-	67.159.52.132
United States, Dallas	ERROR	-	67.159.52.132
United States, Kansas City	ERROR	-	67.159.52.132
United States, Dallas	ERROR	-	67.159.52.132
South Africa, Johannesburg	ERROR	-	67.159.52.132