Open Port Checker
Check if common ports (SSH 22, HTTP 80, HTTPS 443, MySQL 3306, Postgres 5432) are open and accepting connections.
Understanding Port Statuses
• Open: The server is listening on this port and completed the TCP handshake.
• Closed: The server actively rejected the connection (RST packet received).
• Filtered: No response received within 1.8s. A firewall (like Cloudflare, AWS Security Group, or iptables) dropped the SYN packet.