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 65+ 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.

تقرير النطاق br-sao-serversp.check-host.eu:80

Name: Check-Host br-sao-serversp.check-host.eu:80 اختبار اتصال منفذ TCP
Author: Check-Host

Info Ping HTTP TCP UDP MTR DNS

فحص TCP br-sao-serversp.check-host.eu:80

تم الفحص بتوقيت Jul 21, 2026 16:36:28 UTC |

| إعادة الفحص |

الموقع	النتيجة	الوقت	عنوان IP
Albania, Tirana	ERROR	-	153.76.114.145
Australia, Sydney	ERROR	-	153.76.114.145
Bosnia and Herzegovina, Novi Travnik	ERROR	-	153.76.114.145
Bulgaria, Sofia	ERROR	-	153.76.114.145
Brazil, São Paulo	ERROR	-	153.76.114.145
Canada, Montreal	ERROR	-	153.76.114.145
Switzerland, Bern	ERROR	-	153.76.114.145
Switzerland, Zurich	ERROR	-	153.76.114.145
Chile, Santiago	ERROR	-	153.76.114.145
China, Hohhot	ERROR	-	153.76.114.145
Germany, Nuernberg	ERROR	-	153.76.114.145
Germany, Frankfurt am Main	ERROR	-	153.76.114.145
Germany, Limburg	ERROR	-	153.76.114.145
Germany, Frankfurt am Main	ERROR	-	153.76.114.145
Germany, Frankfurt am Main	ERROR	-	153.76.114.145
Germany, Frankfurt am Main	ERROR	-	153.76.114.145
Germany, Koblenz	ERROR	-	153.76.114.145
Denmark, Glostrup Municipality	ERROR	-	-
Spain, Bilbao	ERROR	-	153.76.114.145
Spain, Barcelona	ERROR	-	153.76.114.145
Finland, Helsinki	ERROR	-	153.76.114.145
Finland, Helsinki	ERROR	-	153.76.114.145
France, Gravelines	ERROR	-	153.76.114.145
France, Paris	ERROR	-	153.76.114.145
United Kingdom, London	ERROR	-	153.76.114.145
Georgia, Tbilisi	ERROR	-	br-sao-serversp.check-host.eu
Hong Kong, Hong Kong	ERROR	-	153.76.114.145
Croatia, Zagreb	ERROR	-	153.76.114.145
Hungary, Budapest	ERROR	-	153.76.114.145
Israel, Petach Tikwa	ERROR	-	153.76.114.145
Israel, Netanja	ERROR	-	153.76.114.145
India, New Delhi	ERROR	-	153.76.114.145
Iceland, Reykjavik (Miðborg)	ERROR	-	153.76.114.145
Italy, Como	ERROR	-	153.76.114.145
South Korea, Seoul	ERROR	-	153.76.114.145
Lithuania, Pilaite	ERROR	-	153.76.114.145
Latvia, Riga	ERROR	-	153.76.114.145
Moldova, Chisinau	ERROR	-	153.76.114.145
Netherlands, Amsterdam	ERROR	-	153.76.114.145
Netherlands, Amsterdam	ERROR	-	153.76.114.145
Netherlands, Amsterdam	ERROR	-	153.76.114.145
Netherlands, Amsterdam	ERROR	-	153.76.114.145
Netherlands, Eygelshoven	ERROR	-	153.76.114.145
Norway, Oslo	ERROR	-	153.76.114.145
Poland, Warsaw	ERROR	-	153.76.114.145
Romania, Bacău	ERROR	-	153.76.114.145
Romania, Bucharest	ERROR	-	153.76.114.145
Serbia, Belgrade	ERROR	-	153.76.114.145
Russia, Moscow	ERROR	-	153.76.114.145
Singapore, Singapore	ERROR	-	153.76.114.145
Tor, Onion	ERROR	-	br-sao-serversp.check-host.eu
Tor, Onion	ERROR	-	br-sao-serversp.check-host.eu
Tor, Onion	ERROR	-	br-sao-serversp.check-host.eu
Turkey, Istanbul	ERROR	-	153.76.114.145
Turkey, Istanbul	ERROR	-	153.76.114.145
Taiwan, Taipei	ERROR	-	153.76.114.145
Ukraine, Khmelnytskyi	ERROR	-	153.76.114.145
United States, Dallas	ERROR	-	153.76.114.145
United States, Dallas	ERROR	-	153.76.114.145
United States, Los Angeles	ERROR	-	153.76.114.145
United States, Houston	ERROR	-	153.76.114.145
United States, Miami	ERROR	-	153.76.114.145
South Africa, Johannesburg	ERROR	-	153.76.114.145
South Africa, Johannesburg	ERROR	-	153.76.114.145