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 google.com:80

Info Ping HTTP TCP UDP MTR DNS

Check TCP google.com:80

Checked Apr 23, 2026 16:50:42 UTC |

| Check again |

Location	Result	Time	IP Address
Albania, Tirana	Connected	49.0 ms	172.217.22.238
Australia, Sydney	Connected	0.0 ms	172.217.25.174
Bosnia and Herzegovina, Novi Travnik	Connected	48.0 ms	142.251.140.78
Bulgaria, Sofia	Connected	10.0 ms	192.178.25.238
Canada, Montreal	Connected	1.0 ms	142.250.69.142
Switzerland, Bern	Connected	2.0 ms	74.125.29.139
Chile, Santiago	Connected	1.0 ms	172.217.192.100
China, Hohhot	ERROR	-	142.251.188.102
Germany, Nuernberg	Connected	5.0 ms	142.251.20.138
Germany, Frankfurt am Main	Connected	0.0 ms	142.250.154.139
Germany, Frankfurt am Main	Connected	0.0 ms	142.251.20.100
Germany, Limburg	Connected	2.0 ms	142.251.13.139
Germany, Frankfurt am Main	Connected	1.0 ms	142.251.127.138
Germany, Duesseldorf	Connected	8.0 ms	74.125.133.101
Denmark, Glostrup Municipality	Connected	12.0 ms	192.178.25.14
Spain, Bilbao	Connected	36.0 ms	142.251.13.138
Finland, Helsinki	Connected	51.0 ms	192.178.25.78
Finland, Helsinki	Connected	7.0 ms	172.217.19.238
France, Paris	Connected	9.0 ms	172.217.22.14
United Kingdom, London	Connected	6.0 ms	142.251.29.102
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	24.0 ms	142.251.110.113
Hungary, Budapest	Connected	15.0 ms	172.217.171.174
Indonesia, Jakarta	Connected	1.0 ms	64.233.170.102
Israel, Petach Tikwa	Connected	2.0 ms	142.250.75.46
Israel, Netanja	Connected	3.0 ms	142.250.75.110
India, New Delhi	Connected	1.0 ms	142.250.183.206
Iceland, Reykjavik (Miðborg)	Connected	36.0 ms	172.217.23.238
Italy, Como	Connected	10.0 ms	172.217.23.78
Kuwait, Kuwait City	ERROR	-	google.com
Lithuania, Pilaite	Connected	56.0 ms	172.217.19.238
Latvia, Riga	Connected	31.0 ms	142.250.102.139
Moldova, Chisinau	Connected	36.0 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	142.251.142.206
Norway, Oslo	Connected	33.0 ms	209.85.203.100
Poland, Warsaw	Connected	22.0 ms	142.251.98.139
Romania, Bacău	Connected	33.0 ms	142.251.20.102
Romania, Bucharest	Connected	8.0 ms	172.217.168.110
Serbia, Belgrade	Connected	31.0 ms	142.251.110.102
Singapore, Singapore	Connected	1.0 ms	142.251.10.113
Turkey, Istanbul	Connected	10.0 ms	142.251.142.110
Taiwan, Taipei	Connected	1.0 ms	142.250.204.46
United States, Miami	Connected	1.0 ms	142.251.218.46
United States, Dallas	Connected	18.0 ms	142.251.186.101
United States, Kansas City	Connected	31.0 ms	142.250.152.113
United States, Dallas	Connected	1.0 ms	142.251.186.113
South Africa, Johannesburg	Connected	1.0 ms	142.251.47.14