Port 22 checker
Check whether SSH on port 22 is reachable from the public internet and understand the usual reasons it is blocked.
Ports
Popular ports and service references.
Jump straight into the dedicated checker flow for the port you care about, then open the reference page when you need service context and failure patterns.
Port 80 checker
Check whether HTTP on port 80 is reachable and understand why some sites keep it open only for redirects.
Port 443 checker
Check whether HTTPS on port 443 is externally reachable and why TCP openness does not guarantee TLS or application health.
Port 3389 checker
Check whether Remote Desktop on port 3389 is visible publicly and why exposing it directly is often a deliberate security risk.
Port 25565 checker
Check whether the default Minecraft Java server port is externally reachable and understand the usual router and firewall failure modes.