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.

es-bil-24racks.check-host.eu:80 のレポート

Name: Check-Host es-bil-24racks.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 es-bil-24racks.check-host.eu:80

Apr 20, 2026 21:54:04 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	-	92.113.12.126
Australia, Sydney	ERROR	-	92.113.12.126
Bosnia and Herzegovina, Novi Travnik	ERROR	-	92.113.12.126
Bulgaria, Sofia	ERROR	-	92.113.12.126
Canada, Montreal	ERROR	-	92.113.12.126
Switzerland, Bern	ERROR	-	92.113.12.126
Chile, Santiago	ERROR	-	92.113.12.126
China, Hohhot	ERROR	-	92.113.12.126
Germany, Nuernberg	ERROR	-	92.113.12.126
Germany, Frankfurt am Main	ERROR	-	92.113.12.126
Germany, Frankfurt am Main	ERROR	-	92.113.12.126
Germany, Limburg	ERROR	-	92.113.12.126
Germany, Frankfurt am Main	ERROR	-	92.113.12.126
Germany, Duesseldorf	ERROR	-	92.113.12.126
Denmark, Glostrup Municipality	Connected	12.0 ms	92.113.12.126
Spain, Bilbao	ERROR	-	92.113.12.126
Finland, Helsinki	ERROR	-	92.113.12.126
Finland, Helsinki	ERROR	-	92.113.12.126
France, Gravelines	ERROR	-	92.113.12.126
France, Paris	Connected	9.0 ms	92.113.12.126
United Kingdom, London	ERROR	-	92.113.12.126
Georgia, Tbilisi	ERROR	-	es-bil-24racks.check-host.eu
Greece, Athens	ERROR	-	es-bil-24racks.check-host.eu
Hong Kong, Hong Kong	ERROR	-	92.113.12.126
Croatia, Zagreb	ERROR	-	92.113.12.126
Hungary, Budapest	Connected	15.0 ms	92.113.12.126
Indonesia, Jakarta	ERROR	-	92.113.12.126
Israel, Petach Tikwa	ERROR	-	92.113.12.126
Israel, Netanja	ERROR	-	92.113.12.126
India, New Delhi	ERROR	-	92.113.12.126
Iceland, Reykjavik (Miðborg)	ERROR	-	92.113.12.126
Italy, Como	ERROR	-	92.113.12.126
Kuwait, Kuwait City	ERROR	-	es-bil-24racks.check-host.eu
Lithuania, Pilaite	ERROR	-	92.113.12.126
Latvia, Riga	Connected	31.0 ms	92.113.12.126
Moldova, Chisinau	Connected	35.0 ms	92.113.12.126
Netherlands, Amsterdam	ERROR	-	92.113.12.126
Netherlands, Amsterdam	ERROR	-	92.113.12.126
Netherlands, Amsterdam	ERROR	-	92.113.12.126
Netherlands, Amsterdam	ERROR	-	92.113.12.126
Norway, Oslo	ERROR	-	92.113.12.126
Poland, Warsaw	Connected	16.0 ms	92.113.12.126
Romania, Bacău	ERROR	-	92.113.12.126
Romania, Bucharest	ERROR	-	92.113.12.126
Serbia, Belgrade	Connected	50.0 ms	92.113.12.126
Russia, St Petersburg	ERROR	-	92.113.12.126
Singapore, Singapore	ERROR	-	92.113.12.126
Turkey, Istanbul	ERROR	-	92.113.12.126
Taiwan, Taipei	ERROR	-	92.113.12.126
United States, Miami	ERROR	-	92.113.12.126
United States, Dallas	ERROR	-	92.113.12.126
United States, Kansas City	ERROR	-	92.113.12.126
United States, Dallas	ERROR	-	92.113.12.126
South Africa, Johannesburg	ERROR	-	92.113.12.126