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.

ge-tbi-9.check-host.eu:80 のレポート

Name: Check-Host ge-tbi-9.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 ge-tbi-9.check-host.eu:80

Apr 21, 2026 07:52:52 UTC に確認 |

| 再チェック |

拠点	結果	応答時間	IP アドレス
Albania, Tirana	Connected	114.0 ms	188.93.91.194
Australia, Sydney	Connected	317.0 ms	188.93.91.194
Bosnia and Herzegovina, Novi Travnik	Connected	79.0 ms	188.93.91.194
Bulgaria, Sofia	Connected	75.0 ms	188.93.91.194
Canada, Montreal	Connected	193.0 ms	188.93.91.194
Switzerland, Bern	Connected	72.0 ms	188.93.91.194
Chile, Santiago	Connected	295.0 ms	188.93.91.194
China, Hohhot	Connected	294.0 ms	188.93.91.194
Germany, Nuernberg	Connected	74.0 ms	188.93.91.194
Germany, Frankfurt am Main	Connected	62.0 ms	188.93.91.194
Germany, Frankfurt am Main	Connected	65.0 ms	188.93.91.194
Germany, Limburg	Connected	65.0 ms	188.93.91.194
Germany, Frankfurt am Main	Connected	69.0 ms	188.93.91.194
Germany, Duesseldorf	Connected	74.0 ms	188.93.91.194
Denmark, Glostrup Municipality	Connected	12.0 ms	188.93.91.194
Spain, Bilbao	Connected	112.0 ms	188.93.91.194
Finland, Helsinki	Connected	93.0 ms	188.93.91.194
Finland, Helsinki	Connected	100.0 ms	188.93.91.194
France, Gravelines	Connected	83.0 ms	188.93.91.194
France, Paris	Connected	9.0 ms	188.93.91.194
United Kingdom, London	Connected	85.0 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	79.0 ms	188.93.91.194
Croatia, Zagreb	Connected	75.0 ms	188.93.91.194
Hungary, Budapest	Connected	15.0 ms	188.93.91.194
Indonesia, Jakarta	Connected	300.0 ms	188.93.91.194
Israel, Petach Tikwa	Connected	125.0 ms	188.93.91.194
Israel, Netanja	Connected	113.0 ms	188.93.91.194
India, New Delhi	Connected	328.0 ms	188.93.91.194
Iceland, Reykjavik (Miðborg)	Connected	114.0 ms	188.93.91.194
Italy, Como	Connected	77.0 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	74.0 ms	188.93.91.194
Netherlands, Amsterdam	Connected	79.0 ms	188.93.91.194
Netherlands, Amsterdam	Connected	81.0 ms	188.93.91.194
Netherlands, Amsterdam	Connected	85.0 ms	188.93.91.194
Norway, Oslo	Connected	76.0 ms	188.93.91.194
Poland, Warsaw	Connected	15.0 ms	188.93.91.194
Romania, Bacău	Connected	93.0 ms	188.93.91.194
Romania, Bucharest	Connected	83.0 ms	188.93.91.194
Serbia, Belgrade	Connected	30.0 ms	188.93.91.194
Russia, St Petersburg	Connected	109.0 ms	188.93.91.194
Singapore, Singapore	Connected	313.0 ms	188.93.91.194
Turkey, Istanbul	Connected	106.0 ms	188.93.91.194
Taiwan, Taipei	Connected	303.0 ms	188.93.91.194
United States, Miami	Connected	193.0 ms	188.93.91.194
United States, Dallas	Connected	183.0 ms	188.93.91.194
United States, Kansas City	Connected	204.0 ms	188.93.91.194
United States, Dallas	Connected	187.0 ms	188.93.91.194
South Africa, Johannesburg	Connected	225.0 ms	188.93.91.194