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.

Bericht für 8.8.8.8:53

Info Ping HTTP TCP UDP MTR DNS

TCP prüfen 8.8.8.8:53

Geprüft am Oct 24, 2026 02:29:16 UTC |

| Erneut prüfen |

Standort	Ergebnis	Zeit	IP-Adresse
Albania, Tirana	Connected	212.0 ms	8.8.8.8
Australia, Sydney	Connected	1.0 ms	8.8.8.8
Bosnia and Herzegovina, Novi Travnik	Connected	17.0 ms	8.8.8.8
Bulgaria, Sofia	Connected	2.0 ms	8.8.8.8
Canada, Montreal	Connected	2.0 ms	8.8.8.8
Switzerland, Bern	Connected	1.0 ms	8.8.8.8
Switzerland, Zurich	Connected	19.0 ms	8.8.8.8
China, Hohhot	Connected	208.0 ms	8.8.8.8
Cyprus, Larnaca	Connected	9.0 ms	8.8.8.8
Germany, Nuernberg	Connected	5.0 ms	8.8.8.8
Germany, Frankfurt am Main	Connected	0.0 ms	8.8.8.8
Germany, Frankfurt am Main	Connected	1.0 ms	8.8.8.8
Germany, Frankfurt am Main	Connected	1.0 ms	8.8.8.8
Germany, Koblenz	Connected	20.0 ms	8.8.8.8
Germany, Frankfurt am Main	Connected	4.0 ms	8.8.8.8
Denmark, Glostrup Municipality	Connected	29.0 ms	8.8.8.8
Spain, Bilbao	Connected	38.0 ms	8.8.8.8
Spain, Barcelona	Connected	22.0 ms	8.8.8.8
Finland, Helsinki	Connected	4.0 ms	8.8.8.8
Finland, Helsinki	Connected	11.0 ms	8.8.8.8
France, Gravelines	Connected	4.0 ms	8.8.8.8
France, Paris	Connected	59.0 ms	8.8.8.8
United Kingdom, London	Connected	8.0 ms	8.8.8.8
Hong Kong, Hong Kong	Connected	1.0 ms	8.8.8.8
Croatia, Zagreb	Connected	24.0 ms	8.8.8.8
Hungary, Budapest	Connected	131.0 ms	8.8.8.8
Israel, Petach Tikwa	Connected	2.0 ms	8.8.8.8
Israel, Netanja	Connected	2.0 ms	8.8.8.8
Iran, Tehran	Connected	1.0 ms	8.8.8.8
Iran, Tehran	Connected	3.0 ms	8.8.8.8
Iceland, Reykjavik (Miðborg)	Connected	22.0 ms	8.8.8.8
Italy, Como	Connected	1.0 ms	8.8.8.8
Japan, Tokyo	ERROR	-	-
South Korea, Seoul	Connected	34.0 ms	8.8.8.8
Kazakhstan, Almaty	Connected	85.0 ms	8.8.8.8
Lithuania, Pilaite	Connected	86.0 ms	8.8.8.8
Latvia, Riga	Connected	133.0 ms	8.8.8.8
Moldova, Chisinau	Connected	88.0 ms	8.8.8.8
Netherlands, Amsterdam	Connected	1.0 ms	8.8.8.8
Netherlands, Amsterdam	Connected	3.0 ms	8.8.8.8
Netherlands, Amsterdam	Connected	1.0 ms	8.8.8.8
Netherlands, Amsterdam	Connected	1.0 ms	8.8.8.8
Netherlands, Eygelshoven	Connected	4.0 ms	8.8.8.8
Norway, Oslo	Connected	31.0 ms	8.8.8.8
Poland, Warsaw	Connected	35.0 ms	8.8.8.8
Romania, Bacău	Connected	53.0 ms	8.8.8.8
Romania, Bucharest	Connected	8.0 ms	8.8.8.8
Serbia, Belgrade	Connected	13.0 ms	8.8.8.8
Russia, Moscow	Connected	28.0 ms	8.8.8.8
Singapore, Singapore	Connected	2.0 ms	8.8.8.8
Tor, Onion	Connected	56.0 ms	8.8.8.8
Tor, Onion	Connected	35.0 ms	8.8.8.8
Tor, Onion	Connected	103.0 ms	8.8.8.8
Turkey, Istanbul	Connected	9.0 ms	8.8.8.8
Ukraine, Khmelnytskyi	Connected	32.0 ms	8.8.8.8
United States, Dallas	Connected	7.0 ms	8.8.8.8
United States, Los Angeles	Connected	35.0 ms	8.8.8.8
United States, Houston	Connected	39.0 ms	8.8.8.8
United States, Miami	Connected	1.0 ms	8.8.8.8
South Africa, Johannesburg	Connected	2.0 ms	8.8.8.8