Is This Port Open?

What is a port checker?

A port checker tests whether a specific TCP port on a remote host is accepting connections. When a port is "open", it means there is a service listening on that port and it is reachable from your current network. When a port is "closed" or "filtered", either no service is running on that port or a firewall is blocking the connection.

Common ports and their services

• Port 22 — SSH (Secure Shell). Used for secure remote server access.
• Port 80 — HTTP. Standard unencrypted web traffic.
• Port 443 — HTTPS. Encrypted web traffic (TLS/SSL).
• Port 3306 — MySQL database. Check if your database is accessible.
• Port 5432 — PostgreSQL database.
• Port 27017 — MongoDB. Default port for MongoDB connections.
• Port 6379 — Redis. In-memory data store.
• Port 8080 — HTTP alternative, commonly used for development servers.

Why would a port appear closed?

A port can appear closed for several reasons: no service is listening on that port, a firewall (like AWS Security Groups, UFW, or iptables) is blocking the connection, or the host is offline. If you expect a port to be open, use our IP Whitelist Config Generator to add your IP to the relevant firewall rules.