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.

Report for il-pet-cloudlease.check-host.eu:80

Name: Check-Host il-pet-cloudlease.check-host.eu:80 TCP Port Connectivity Test
Author: Check-Host

Info Ping HTTP TCP UDP MTR DNS

Check TCP il-pet-cloudlease.check-host.eu:80

Checked Oct 22, 2026 22:02:00 UTC |

| Check again |

Location	Result	Time	IP Address
Australia, Sydney	ERROR	-	94.154.123.222
Bosnia and Herzegovina, Novi Travnik	ERROR	-	94.154.123.222
Bulgaria, Sofia	ERROR	-	94.154.123.222
Canada, Montreal	ERROR	-	94.154.123.222
Switzerland, Bern	ERROR	-	94.154.123.222
Switzerland, Zurich	ERROR	-	94.154.123.222
China, Hohhot	ERROR	-	94.154.123.222
Cyprus, Larnaca	ERROR	-	94.154.123.222
Germany, Nuernberg	ERROR	-	94.154.123.222
Germany, Frankfurt am Main	ERROR	-	94.154.123.222
Germany, Frankfurt am Main	ERROR	-	94.154.123.222
Germany, Frankfurt am Main	ERROR	-	94.154.123.222
Germany, Koblenz	ERROR	-	94.154.123.222
Germany, Frankfurt am Main	ERROR	-	94.154.123.222
Denmark, Glostrup Municipality	ERROR	-	94.154.123.222
Spain, Bilbao	ERROR	-	94.154.123.222
Spain, Barcelona	ERROR	-	94.154.123.222
Finland, Helsinki	ERROR	-	94.154.123.222
Finland, Helsinki	ERROR	-	94.154.123.222
France, Gravelines	ERROR	-	94.154.123.222
France, Paris	ERROR	-	94.154.123.222
United Kingdom, London	ERROR	-	94.154.123.222
Hong Kong, Hong Kong	ERROR	-	94.154.123.222
Croatia, Zagreb	ERROR	-	94.154.123.222
Hungary, Budapest	ERROR	-	94.154.123.222
Israel, Petach Tikwa	ERROR	-	94.154.123.222
Israel, Netanja	ERROR	-	94.154.123.222
Iran, Tehran	ERROR	-	94.154.123.222
Iran, Tehran	ERROR	-	94.154.123.222
Iceland, Reykjavik (Miðborg)	ERROR	-	94.154.123.222
Italy, Como	ERROR	-	94.154.123.222
Japan, Tokyo	ERROR	-	-
South Korea, Seoul	ERROR	-	94.154.123.222
Kazakhstan, Almaty	ERROR	-	94.154.123.222
Lithuania, Pilaite	ERROR	-	94.154.123.222
Latvia, Riga	ERROR	-	94.154.123.222
Netherlands, Amsterdam	ERROR	-	94.154.123.222
Netherlands, Amsterdam	ERROR	-	94.154.123.222
Netherlands, Amsterdam	ERROR	-	94.154.123.222
Netherlands, Amsterdam	ERROR	-	94.154.123.222
Netherlands, Eygelshoven	ERROR	-	94.154.123.222
Norway, Oslo	ERROR	-	94.154.123.222
Poland, Warsaw	ERROR	-	94.154.123.222
Romania, Bacău	ERROR	-	94.154.123.222
Romania, Bucharest	ERROR	-	94.154.123.222
Serbia, Belgrade	ERROR	-	94.154.123.222
Russia, Moscow	ERROR	-	94.154.123.222
Singapore, Singapore	ERROR	-	94.154.123.222
Tor, Onion	ERROR	-	il-pet-cloudlease.check-host.eu
Tor, Onion	ERROR	-	il-pet-cloudlease.check-host.eu
Tor, Onion	ERROR	-	il-pet-cloudlease.check-host.eu
Turkey, Istanbul	ERROR	-	94.154.123.222
Ukraine, Khmelnytskyi	ERROR	-	94.154.123.222
United States, Dallas	ERROR	-	94.154.123.222
United States, Los Angeles	ERROR	-	94.154.123.222
United States, Houston	ERROR	-	94.154.123.222
United States, Miami	ERROR	-	94.154.123.222
South Africa, Johannesburg	ERROR	-	94.154.123.222