How to use WhenIP Port Check
WhenIP Port Check is designed for quick and safe checks against the public IP your current browser session is presenting. It is intentionally narrow so it can stay useful without becoming an abuse surface.
- How to enter a valid port.
- How to read open, closed, and filtered results.
- What to try next after the check finishes.
Step 1: confirm the target IP
The port checker always works against the public IP your browser currently presents to the selected family.
If you are testing through a VPN, you are testing the VPN-facing public IP, not necessarily the local device.
Step 2: enter one allowed port
Use a single numeric port from the safe allowlist.
Examples include 80, 443, 22, 53, 8080, and 8443 depending on the configured allowlist.
Step 3: read the summary first
The status strip gives a plain-English result such as open, closed, or filtered.
The console provides the supporting details and timing.
Step 4: use the right follow-up
Open: verify the application is the one you expect.
Closed: check whether the service is listening.
Filtered: review firewalls, NAT, upstream ACLs, or path issues.
Why can I only enter one port?
Because the public tool is intentionally restricted for safety.
Why does filtered not tell me exactly which firewall blocked it?
Because a timeout only shows that no clear response came back.
Last updated: March 29, 2026