Open Port Checker
Reference guide for well-known TCP/UDP port numbers and their associated services.
About Open Port Checker
TCP and UDP port numbers identify specific services running on a host. Ports 0-1023 are well-known ports reserved for common services. Ports 1024-49151 are registered ports for applications. Ports 49152-65535 are dynamic/ephemeral ports. This tool provides a searchable reference of the most important port assignments, useful when configuring firewalls, diagnosing connectivity issues, and understanding network traffic.
FAQ
Which ports should I open in my firewall?
Only open ports that are necessary for your application. Minimum for a web server: 80 (HTTP) and 443 (HTTPS). Add 22 (SSH) for administration but restrict to specific IP ranges. Never expose database ports (3306, 5432, 27017) to the internet — use a VPN or bastion host for database access.