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.

Report for golem.de:80

Info Ping HTTP TCP UDP MTR DNS

Check TCP golem.de:80

Checked Apr 23, 2026 18:55:56 UTC |

| Check again |

Location	Result	Time	IP Address
Albania, Tirana	Connected	85.0 ms	77.247.84.129
Australia, Sydney	Connected	290.0 ms	77.247.84.129
Bosnia and Herzegovina, Novi Travnik	Connected	31.0 ms	77.247.84.129
Bulgaria, Sofia	Connected	47.0 ms	77.247.84.129
Canada, Montreal	Connected	106.0 ms	77.247.84.129
Switzerland, Bern	Connected	16.0 ms	77.247.84.129
Chile, Santiago	Connected	206.0 ms	77.247.84.129
China, Hohhot	Connected	300.0 ms	77.247.84.129
Germany, Nuernberg	Connected	13.0 ms	77.247.84.129
Germany, Frankfurt am Main	Connected	9.0 ms	77.247.84.129
Germany, Frankfurt am Main	Connected	9.0 ms	77.247.84.129
Germany, Limburg	Connected	10.0 ms	77.247.84.129
Germany, Frankfurt am Main	Connected	9.0 ms	77.247.84.129
Germany, Duesseldorf	Connected	13.0 ms	77.247.84.129
Denmark, Glostrup Municipality	Connected	12.0 ms	77.247.84.129
Spain, Bilbao	Connected	56.0 ms	77.247.84.129
Finland, Helsinki	Connected	71.0 ms	77.247.84.129
Finland, Helsinki	Connected	32.0 ms	77.247.84.129
France, Paris	Connected	9.0 ms	77.247.84.129
United Kingdom, London	Connected	29.0 ms	77.247.84.129
Georgia, Tbilisi	ERROR	-	golem.de
Greece, Athens	ERROR	-	golem.de
Hong Kong, Hong Kong	Connected	16.0 ms	77.247.84.129
Croatia, Zagreb	Connected	27.0 ms	77.247.84.129
Hungary, Budapest	Connected	15.0 ms	77.247.84.129
Indonesia, Jakarta	Connected	250.0 ms	77.247.84.129
Israel, Petach Tikwa	Connected	68.0 ms	77.247.84.129
Israel, Netanja	Connected	66.0 ms	77.247.84.129
India, New Delhi	Connected	274.0 ms	77.247.84.129
Iceland, Reykjavik (Miðborg)	Connected	54.0 ms	77.247.84.129
Italy, Como	Connected	19.0 ms	77.247.84.129
Kuwait, Kuwait City	ERROR	-	golem.de
Lithuania, Pilaite	Connected	67.0 ms	77.247.84.129
Latvia, Riga	Connected	32.0 ms	77.247.84.129
Moldova, Chisinau	Connected	62.0 ms	77.247.84.129
Netherlands, Amsterdam	Connected	13.0 ms	77.247.84.129
Netherlands, Amsterdam	Connected	16.0 ms	77.247.84.129
Netherlands, Amsterdam	Connected	13.0 ms	77.247.84.129
Netherlands, Amsterdam	Connected	13.0 ms	77.247.84.129
Norway, Oslo	Connected	34.0 ms	77.247.84.129
Poland, Warsaw	ERROR	-	-
Romania, Bacău	Connected	45.0 ms	77.247.84.129
Romania, Bucharest	Connected	36.0 ms	77.247.84.129
Serbia, Belgrade	ERROR	-	-
Singapore, Singapore	Connected	173.0 ms	77.247.84.129
Turkey, Istanbul	Connected	44.0 ms	77.247.84.129
Taiwan, Taipei	Connected	249.0 ms	77.247.84.129
United States, Miami	Connected	131.0 ms	77.247.84.129
United States, Dallas	Connected	130.0 ms	77.247.84.129
United States, Kansas City	Connected	129.0 ms	77.247.84.129
United States, Dallas	Connected	135.0 ms	77.247.84.129
South Africa, Johannesburg	Connected	173.0 ms	77.247.84.129