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 20, 2026 22:04:42 UTC |

| Erneut prüfen |

Standort	Ergebnis	Zeit	IP-Adresse
Albania, Tirana	Connected	94.0 ms	192.178.24.174
Australia, Sydney	Connected	0.0 ms	142.250.195.142
Bosnia and Herzegovina, Novi Travnik	Connected	48.0 ms	142.251.140.78
Bulgaria, Sofia	Connected	0.0 ms	192.178.25.238
Canada, Montreal	Connected	1.0 ms	142.250.69.142
Switzerland, Bern	Connected	2.0 ms	74.125.29.102
Chile, Santiago	Connected	1.0 ms	64.233.190.100
China, Hohhot	ERROR	-	142.250.73.142
Germany, Nuernberg	Connected	5.0 ms	142.251.14.138
Germany, Frankfurt am Main	Connected	0.0 ms	142.251.20.102
Germany, Frankfurt am Main	Connected	1.0 ms	142.251.20.139
Germany, Limburg	Connected	1.0 ms	142.251.110.139
Germany, Frankfurt am Main	Connected	0.0 ms	192.178.183.138
Germany, Duesseldorf	Connected	7.0 ms	142.251.168.138
Denmark, Glostrup Municipality	Connected	12.0 ms	192.178.25.14
Spain, Bilbao	Connected	37.0 ms	142.251.13.100
Finland, Helsinki	Connected	136.0 ms	192.178.155.102
Finland, Helsinki	Connected	8.0 ms	142.251.143.142
France, Gravelines	Connected	11.0 ms	142.251.14.101
France, Paris	Connected	9.0 ms	142.251.39.110
United Kingdom, London	Connected	6.0 ms	142.250.129.113
Georgia, Tbilisi	ERROR	-	google.com
Greece, Athens	ERROR	-	google.com
Hong Kong, Hong Kong	Connected	4.0 ms	172.217.171.110
Croatia, Zagreb	Connected	25.0 ms	142.251.110.101
Hungary, Budapest	Connected	61.0 ms	172.217.171.174
Indonesia, Jakarta	Connected	0.0 ms	172.253.118.100
Israel, Petach Tikwa	Connected	1.0 ms	142.250.75.46
Israel, Netanja	Connected	1.0 ms	142.250.75.46
India, New Delhi	Connected	1.0 ms	172.217.24.238
Iceland, Reykjavik (Miðborg)	Connected	36.0 ms	172.217.23.238
Italy, Como	Connected	30.0 ms	142.251.209.46
Kuwait, Kuwait City	ERROR	-	google.com
Lithuania, Pilaite	Connected	59.0 ms	172.217.19.238
Latvia, Riga	Connected	40.0 ms	142.250.102.100
Moldova, Chisinau	Connected	113.0 ms	192.178.24.174
Netherlands, Amsterdam	Connected	1.0 ms	142.251.142.206
Netherlands, Amsterdam	Connected	3.0 ms	192.178.25.206
Netherlands, Amsterdam	Connected	1.0 ms	172.217.23.238
Netherlands, Amsterdam	Connected	1.0 ms	172.217.23.238
Norway, Oslo	Connected	32.0 ms	209.85.203.100
Poland, Warsaw	Connected	16.0 ms	142.251.98.101
Romania, Bacău	Connected	34.0 ms	142.251.20.102
Romania, Bucharest	Connected	9.0 ms	172.217.21.206
Serbia, Belgrade	Connected	88.0 ms	142.251.20.139
Russia, St Petersburg	Connected	12.0 ms	142.251.143.142
Singapore, Singapore	Connected	1.0 ms	172.217.194.138
Turkey, Istanbul	Connected	9.0 ms	142.251.142.110
Taiwan, Taipei	Connected	1.0 ms	142.250.204.46
United States, Miami	Connected	61.0 ms	142.251.210.78
United States, Dallas	Connected	18.0 ms	142.250.115.139
United States, Kansas City	Connected	31.0 ms	142.251.184.139
United States, Dallas	Connected	2.0 ms	142.251.116.102
South Africa, Johannesburg	Connected	0.0 ms	142.251.47.142