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 t1-tor-2.check-host.eu:80

Name: Check-Host t1-tor-2.check-host.eu:80 Kiểm Tra Kết Nối Cổng TCP
Author: Check-Host

Info Ping HTTP TCP UDP MTR DNS

Check TCP t1-tor-2.check-host.eu:80

Checked Apr 30, 2026 14:02:27 UTC |

| Check again |

Location	Result	Time	IP Address
Albania, Tirana	Connected	114.0 ms	85.195.253.142
Australia, Sydney	Connected	270.0 ms	85.195.253.142
Bosnia and Herzegovina, Novi Travnik	Connected	32.0 ms	85.195.253.142
Bulgaria, Sofia	Connected	32.0 ms	85.195.253.142
Canada, Montreal	Connected	99.0 ms	85.195.253.142
Switzerland, Bern	Connected	6.0 ms	85.195.253.142
Chile, Santiago	Connected	208.0 ms	85.195.253.142
China, Hohhot	ERROR	-	85.195.253.142
Germany, Nuernberg	Connected	11.0 ms	85.195.253.142
Germany, Frankfurt am Main	Connected	19.0 ms	85.195.253.142
Germany, Frankfurt am Main	Connected	9.0 ms	85.195.253.142
Germany, Limburg	Connected	12.0 ms	85.195.253.142
Germany, Frankfurt am Main	Connected	19.0 ms	85.195.253.142
Denmark, Glostrup Municipality	Connected	12.0 ms	85.195.253.142
Spain, Bilbao	Connected	60.0 ms	85.195.253.142
Finland, Helsinki	Connected	35.0 ms	85.195.253.142
Finland, Helsinki	Connected	41.0 ms	85.195.253.142
France, Gravelines	Connected	20.0 ms	85.195.253.142
France, Paris	Connected	9.0 ms	85.195.253.142
United Kingdom, London	Connected	24.0 ms	85.195.253.142
Georgia, Tbilisi	ERROR	-	t1-tor-2.check-host.eu
Hong Kong, Hong Kong	Connected	16.0 ms	85.195.253.142
Croatia, Zagreb	Connected	54.0 ms	85.195.253.142
Hungary, Budapest	Connected	15.0 ms	85.195.253.142
Indonesia, Jakarta	Connected	251.0 ms	85.195.253.142
Israel, Petach Tikwa	Connected	89.0 ms	85.195.253.142
Israel, Netanja	Connected	86.0 ms	85.195.253.142
India, New Delhi	Connected	265.0 ms	85.195.253.142
Iceland, Reykjavik (Miðborg)	Connected	54.0 ms	85.195.253.142
Italy, Como	Connected	19.0 ms	85.195.253.142
Lithuania, Pilaite	Connected	149.0 ms	85.195.253.142
Latvia, Riga	Connected	56.0 ms	85.195.253.142
Moldova, Chisinau	Connected	128.0 ms	85.195.253.142
Netherlands, Amsterdam	Connected	14.0 ms	85.195.253.142
Netherlands, Amsterdam	Connected	16.0 ms	85.195.253.142
Netherlands, Amsterdam	Connected	14.0 ms	85.195.253.142
Netherlands, Amsterdam	Connected	14.0 ms	85.195.253.142
Norway, Oslo	Connected	29.0 ms	85.195.253.142
Poland, Warsaw	Connected	22.0 ms	85.195.253.142
Romania, Bacău	Connected	45.0 ms	85.195.253.142
Romania, Bucharest	Connected	34.0 ms	85.195.253.142
Serbia, Belgrade	Connected	82.0 ms	85.195.253.142
Russia, Moscow	Connected	49.0 ms	85.195.253.142
Saudi Arabia, Riyadh	Connected	208.0 ms	85.195.253.142
Singapore, Singapore	Connected	173.0 ms	85.195.253.142
Tor, Onion	Connected	77.0 ms	t1-tor-2.check-host.eu
Tor, Onion	Connected	281.0 ms	t1-tor-2.check-host.eu
Tor, Onion	Connected	253.0 ms	t1-tor-2.check-host.eu
Turkey, Istanbul	Connected	44.0 ms	85.195.253.142
Taiwan, Taipei	Connected	255.0 ms	85.195.253.142
United States, Miami	Connected	120.0 ms	85.195.253.142
United States, Dallas	Connected	130.0 ms	85.195.253.142
United States, Kansas City	Connected	121.0 ms	85.195.253.142
United States, Dallas	Connected	130.0 ms	85.195.253.142
South Africa, Johannesburg	Connected	166.0 ms	85.195.253.142