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.

hk-hon-storm.check-host.eu:80 のレポート

Name: Check-Host hk-hon-storm.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 hk-hon-storm.check-host.eu:80

Apr 21, 2026 14:00:18 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	-	176.65.139.108
Australia, Sydney	ERROR	-	176.65.139.108
Bosnia and Herzegovina, Novi Travnik	ERROR	-	176.65.139.108
Bulgaria, Sofia	ERROR	-	176.65.139.108
Canada, Montreal	ERROR	-	176.65.139.108
Switzerland, Bern	ERROR	-	176.65.139.108
Chile, Santiago	ERROR	-	176.65.139.108
China, Hohhot	ERROR	-	176.65.139.108
Germany, Nuernberg	ERROR	-	176.65.139.108
Germany, Frankfurt am Main	ERROR	-	176.65.139.108
Germany, Frankfurt am Main	ERROR	-	176.65.139.108
Germany, Limburg	ERROR	-	176.65.139.108
Germany, Frankfurt am Main	ERROR	-	176.65.139.108
Germany, Duesseldorf	ERROR	-	176.65.139.108
Denmark, Glostrup Municipality	Connected	12.0 ms	176.65.139.108
Spain, Bilbao	ERROR	-	176.65.139.108
Finland, Helsinki	ERROR	-	176.65.139.108
Finland, Helsinki	ERROR	-	176.65.139.108
France, Gravelines	ERROR	-	176.65.139.108
France, Paris	Connected	9.0 ms	176.65.139.108
United Kingdom, London	ERROR	-	176.65.139.108
Georgia, Tbilisi	ERROR	-	hk-hon-storm.check-host.eu
Greece, Athens	ERROR	-	hk-hon-storm.check-host.eu
Hong Kong, Hong Kong	ERROR	-	176.65.139.108
Croatia, Zagreb	ERROR	-	176.65.139.108
Hungary, Budapest	Connected	15.0 ms	176.65.139.108
Indonesia, Jakarta	ERROR	-	176.65.139.108
Israel, Petach Tikwa	ERROR	-	176.65.139.108
Israel, Netanja	ERROR	-	176.65.139.108
India, New Delhi	ERROR	-	176.65.139.108
Iceland, Reykjavik (Miðborg)	ERROR	-	176.65.139.108
Italy, Como	ERROR	-	176.65.139.108
Kuwait, Kuwait City	ERROR	-	hk-hon-storm.check-host.eu
Lithuania, Pilaite	ERROR	-	176.65.139.108
Latvia, Riga	Connected	31.0 ms	176.65.139.108
Moldova, Chisinau	Connected	35.0 ms	176.65.139.108
Netherlands, Amsterdam	ERROR	-	176.65.139.108
Netherlands, Amsterdam	ERROR	-	176.65.139.108
Netherlands, Amsterdam	ERROR	-	176.65.139.108
Netherlands, Amsterdam	ERROR	-	176.65.139.108
Norway, Oslo	ERROR	-	176.65.139.108
Poland, Warsaw	Connected	15.0 ms	176.65.139.108
Romania, Bacău	ERROR	-	176.65.139.108
Romania, Bucharest	ERROR	-	176.65.139.108
Serbia, Belgrade	Connected	58.0 ms	176.65.139.108
Russia, St Petersburg	ERROR	-	176.65.139.108
Singapore, Singapore	ERROR	-	176.65.139.108
Turkey, Istanbul	ERROR	-	176.65.139.108
Taiwan, Taipei	ERROR	-	176.65.139.108
United States, Miami	ERROR	-	176.65.139.108
United States, Dallas	ERROR	-	176.65.139.108
United States, Kansas City	ERROR	-	176.65.139.108
United States, Dallas	ERROR	-	176.65.139.108
South Africa, Johannesburg	ERROR	-	176.65.139.108