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.

pl-war-fns.check-host.eu:80 のレポート

Name: Check-Host pl-war-fns.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 pl-war-fns.check-host.eu:80

Apr 21, 2026 04:49:53 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	-	85.237.212.100
Australia, Sydney	ERROR	-	85.237.212.100
Bosnia and Herzegovina, Novi Travnik	ERROR	-	85.237.212.100
Bulgaria, Sofia	ERROR	-	85.237.212.100
Canada, Montreal	ERROR	-	85.237.212.100
Switzerland, Bern	ERROR	-	85.237.212.100
Chile, Santiago	ERROR	-	85.237.212.100
China, Hohhot	ERROR	-	85.237.212.100
Germany, Nuernberg	ERROR	-	85.237.212.100
Germany, Frankfurt am Main	ERROR	-	85.237.212.100
Germany, Frankfurt am Main	ERROR	-	85.237.212.100
Germany, Limburg	ERROR	-	85.237.212.100
Germany, Frankfurt am Main	ERROR	-	85.237.212.100
Germany, Duesseldorf	ERROR	-	85.237.212.100
Denmark, Glostrup Municipality	Connected	12.0 ms	85.237.212.100
Spain, Bilbao	ERROR	-	85.237.212.100
Finland, Helsinki	ERROR	-	85.237.212.100
Finland, Helsinki	ERROR	-	85.237.212.100
France, Gravelines	ERROR	-	85.237.212.100
France, Paris	Connected	9.0 ms	85.237.212.100
United Kingdom, London	ERROR	-	85.237.212.100
Georgia, Tbilisi	ERROR	-	pl-war-fns.check-host.eu
Greece, Athens	ERROR	-	pl-war-fns.check-host.eu
Hong Kong, Hong Kong	ERROR	-	85.237.212.100
Croatia, Zagreb	ERROR	-	85.237.212.100
Hungary, Budapest	Connected	29.0 ms	85.237.212.100
Indonesia, Jakarta	ERROR	-	85.237.212.100
Israel, Petach Tikwa	ERROR	-	85.237.212.100
Israel, Netanja	ERROR	-	85.237.212.100
India, New Delhi	ERROR	-	85.237.212.100
Iceland, Reykjavik (Miðborg)	ERROR	-	85.237.212.100
Italy, Como	ERROR	-	85.237.212.100
Kuwait, Kuwait City	ERROR	-	pl-war-fns.check-host.eu
Lithuania, Pilaite	ERROR	-	85.237.212.100
Latvia, Riga	Connected	65.0 ms	85.237.212.100
Moldova, Chisinau	Connected	70.0 ms	85.237.212.100
Netherlands, Amsterdam	ERROR	-	85.237.212.100
Netherlands, Amsterdam	ERROR	-	85.237.212.100
Netherlands, Amsterdam	ERROR	-	85.237.212.100
Netherlands, Amsterdam	ERROR	-	85.237.212.100
Norway, Oslo	ERROR	-	85.237.212.100
Poland, Warsaw	Connected	15.0 ms	85.237.212.100
Romania, Bacău	ERROR	-	85.237.212.100
Romania, Bucharest	ERROR	-	85.237.212.100
Serbia, Belgrade	Connected	59.0 ms	85.237.212.100
Russia, St Petersburg	ERROR	-	85.237.212.100
Singapore, Singapore	ERROR	-	85.237.212.100
Turkey, Istanbul	ERROR	-	85.237.212.100
Taiwan, Taipei	ERROR	-	85.237.212.100
United States, Miami	ERROR	-	85.237.212.100
United States, Dallas	ERROR	-	85.237.212.100
United States, Kansas City	ERROR	-	85.237.212.100
United States, Dallas	ERROR	-	85.237.212.100
South Africa, Johannesburg	ERROR	-	85.237.212.100