Scan top 20 common ports on any host.
Port scanning identifies which network ports on a server are open and accepting connections. Every service listens on a specific port — web servers on 80/443, SSH on 22, email on 25/587, FTP on 21, databases on 3306 (MySQL) or 5432 (PostgreSQL).
Unnecessary open ports expand your attack surface. Attackers scan for exposed services running outdated or vulnerable software to gain unauthorized access. Regular port scanning helps verify firewall rules and ensure only required services are accessible.
This tool checks the top 20 most commonly targeted ports on any domain or IP, reporting which are open and identifying associated services.
We check a fixed set of commonly used ports (top 20 style), not a full 1–65535 sweep.
Only scan hosts you own or have permission to test. Unauthorized scanning can trigger abuse reports.
Firewalls often allow HTTPS (443) from the public internet while ICMP or other probes are filtered differently; results reflect reachability of the probed ports from our network.
Open ports are network entry points — each listening service (HTTP on 80, HTTPS on 443, SSH on 22, databases on 3306/5432) accepts connections. This tool probes the most common ports on a host and reports which are open, closed, or filtered. It helps administrators verify firewall rules, detect accidentally exposed services, and confirm only intended ports are reachable from the internet.
Open — a service accepted the connection; verify this is intentional. Closed — host responded with refusal; port is reachable but no service listens (good for unused ports). Filtered — firewall dropped packets; port state hidden from external view (typical for well-configured servers).
Unexpected open ports on 3306 (MySQL), 6379 (Redis), 27017 (MongoDB), or 3389 (RDP) are critical findings — these should never face the public internet without VPN or IP allowlisting.
A startup's API was "secure" behind authentication, but port scanning revealed PostgreSQL on 5432 open globally. An automated bot could have brute-forced credentials within hours. Closing the security group to application-tier IPs only eliminated the exposure.
Only scan systems you own or have written authorization to test. Unauthorized port scanning may violate computer misuse laws and our Terms of Service. This tool probes a fixed list of common ports — not a full 65535-port sweep.
Port Scanning Basics · Website Health Check (full mode) · Traceroute · Security Checklist