Open Port Test
Test multiple common TCP ports on a host at once to see which are open, closed or filtered.
About Open Port Testing
An open port test attempts a TCP connection to a specific port on a host to determine whether the port is reachable and accepting connections from the outside. This is particularly useful for verifying firewall rules, confirming that a service is accessible externally, or troubleshooting connectivity issues.
Port states
- Open — The TCP connection succeeded. A service is listening on that port and accepting connections from the test source.
- Closed — The host is reachable but actively refused the connection (TCP RST). The port is closed at the application level but the host is up.
- Filtered / Timed out — No response was received. A firewall, router, or network ACL is dropping packets silently without sending an RST. The host may or may not be up.
Common ports reference
- 80 — HTTP
- 443 — HTTPS
- 22 — SSH
- 25 / 465 / 587 — SMTP (email sending)
- 110 / 995 — POP3 / POP3S (email retrieval)
- 143 / 993 — IMAP / IMAPS
- 3306 — MySQL
- 5432 — PostgreSQL
- 3389 — RDP (Remote Desktop)
This test connects from the ToolForge server. It checks external reachability — useful for confirming that your server is accessible from the internet, or that your firewall/NAT rules are working correctly.
Frequently asked questions
What ports are tested?
The tool tests a set of commonly used ports covering web, email, SSH, database and remote access services. You can also select a custom set of ports to test.