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.

Bericht für google.com:80

Info Ping HTTP TCP UDP MTR DNS

TCP prüfen google.com:80

Geprüft am Apr 22, 2026 18:36:50 UTC |

| Erneut prüfen |

Standort	Ergebnis	Zeit	IP-Adresse
Albania, Tirana	Connected	49.0 ms	192.178.24.174
Australia, Sydney	Connected	0.0 ms	142.250.195.238
Bosnia and Herzegovina, Novi Travnik	Connected	50.0 ms	142.251.140.78
Bulgaria, Sofia	Connected	1.0 ms	172.217.21.238
Canada, Montreal	Connected	1.0 ms	142.250.69.142
Switzerland, Bern	Connected	3.0 ms	74.125.29.102
Chile, Santiago	Connected	0.0 ms	142.250.0.113
China, Hohhot	ERROR	-	142.250.73.110
Germany, Nuernberg	Connected	5.0 ms	142.251.20.113
Germany, Frankfurt am Main	Connected	1.0 ms	142.251.127.138
Germany, Frankfurt am Main	Connected	0.0 ms	142.250.154.100
Germany, Limburg	Connected	2.0 ms	142.251.13.139
Germany, Frankfurt am Main	Connected	0.0 ms	142.251.110.138
Germany, Duesseldorf	Connected	8.0 ms	74.125.133.100
Denmark, Glostrup Municipality	Connected	12.0 ms	142.251.143.142
Spain, Bilbao	Connected	37.0 ms	142.251.13.102
Finland, Helsinki	Connected	35.0 ms	192.178.25.78
Finland, Helsinki	Connected	16.0 ms	216.58.198.206
France, Gravelines	Connected	11.0 ms	192.178.183.139
France, Paris	Connected	9.0 ms	172.217.22.14
United Kingdom, London	Connected	6.0 ms	142.250.151.139
Georgia, Tbilisi	ERROR	-	google.com
Greece, Athens	ERROR	-	google.com
Hong Kong, Hong Kong	Connected	4.0 ms	216.58.198.14
Croatia, Zagreb	Connected	25.0 ms	142.251.110.139
Hungary, Budapest	Connected	15.0 ms	172.217.171.174
Indonesia, Jakarta	Connected	0.0 ms	74.125.68.139
Israel, Petach Tikwa	Connected	1.0 ms	142.250.75.110
Israel, Netanja	Connected	2.0 ms	142.250.75.110
India, New Delhi	Connected	1.0 ms	142.251.223.206
Iceland, Reykjavik (Miðborg)	Connected	25.0 ms	209.85.202.101
Italy, Como	Connected	26.0 ms	192.178.203.139
Kuwait, Kuwait City	ERROR	-	google.com
Lithuania, Pilaite	Connected	56.0 ms	172.217.19.238
Latvia, Riga	Connected	31.0 ms	142.250.102.100
Moldova, Chisinau	Connected	36.0 ms	192.178.24.174
Netherlands, Amsterdam	Connected	1.0 ms	142.251.142.206
Netherlands, Amsterdam	Connected	2.0 ms	172.217.23.238
Netherlands, Amsterdam	Connected	1.0 ms	172.217.23.238
Netherlands, Amsterdam	Connected	1.0 ms	142.251.209.238
Norway, Oslo	Connected	48.0 ms	209.85.203.100
Poland, Warsaw	Connected	22.0 ms	142.251.98.101
Romania, Bacău	Connected	35.0 ms	142.251.20.101
Romania, Bucharest	Connected	8.0 ms	172.217.168.110
Serbia, Belgrade	Connected	36.0 ms	142.251.110.102
Singapore, Singapore	Connected	1.0 ms	142.250.4.102
Turkey, Istanbul	Connected	10.0 ms	142.251.208.110
Taiwan, Taipei	Connected	1.0 ms	142.250.204.46
United States, Miami	Connected	1.0 ms	192.178.50.78
United States, Dallas	Connected	18.0 ms	173.194.208.100
United States, Kansas City	Connected	40.0 ms	142.251.184.102
United States, Dallas	Connected	2.0 ms	142.250.26.100
South Africa, Johannesburg	Connected	0.0 ms	192.178.54.46