Port Scanner
Scan network ports to check connectivity and security status of any host or IP address.
Port Status Types
- • Open: Service is accepting connections
- • Closed: Port is reachable but no service listening
- • Filtered: Firewall blocking the port
Common Ports
- • 21: FTP • 22: SSH
- • 80: HTTP • 443: HTTPS
- • 3306: MySQL • 5432: PostgreSQL
- • 3389: RDP • 8080: Alt HTTP
Port Scanner by Host
Port scanning tests TCP connections to specific ports on a host or IP address, revealing which services are reachable from the internet — essential for network security audits.
Every server exposes services on numbered ports. Port 80 serves HTTP, port 443 serves HTTPS, port 22 serves SSH. A port scanner tests these connections to determine which ports are open, closed, or filtered by a firewall. Open ports represent running services; closed ports are reachable but idle; filtered ports are blocked by a firewall and return no response. Knowing which ports are exposed is the first step in any security assessment.
What is Port Scanning?
Port scanning probes a host's TCP or UDP ports to identify which services are accepting connections — the foundational technique for network diagnostics and security assessments.
Port scanning works by attempting TCP connections to each target port. The response — a SYN-ACK (open), RST (closed), or timeout (filtered) — tells you the port's state. Our scanner performs TCP connect scans on up to 20 ports per request. These scans are intended for hosts you own or have explicit permission to test. Never scan hosts you do not own or control without written authorization.
Open, Closed & Filtered Ports
An open port means a service is running and accepting connections. A closed port is reachable but idle. A filtered port is blocked by a firewall and returns no response.
Understanding port states helps you map your attack surface. Open ports are the primary concern: each one represents a service that could have vulnerabilities. Closed ports are not a risk but confirm network reachability. Filtered ports indicate firewall rules are blocking access — generally the desired state for any port not intentionally exposed. Security teams use port scan results to verify firewall rules are enforced correctly and to identify unintended service exposure.
Port Scanning for Security Audits
Security auditors use port scanning to enumerate exposed services, verify firewall rules, and identify unauthorized services running on production hosts.
Regular port scanning is a core practice in vulnerability management. By scanning your own perimeter periodically, you can detect misconfigured firewalls, accidentally exposed services (like a test database or internal API), and rogue processes listening on unexpected ports. Our presets for Web, Email, Database, and Remote Access make routine checks fast. For full assessments, combine port scanning with vulnerability scanning using tools like Nmap or Nessus.
Verify firewall rules and detect exposed services on any host instantly.
Scan ports nowUse Cases
SysAdmins use port scanning to verify that only intended services are exposed after firewall rule changes. Security teams use it as part of perimeter audits to confirm that databases (3306, 5432) and admin interfaces (8080, 9200) are not accessible from the internet. DevOps engineers use it in CI pipelines to catch unintended port exposure in staging environments before production deployment.
Popular Port Scan Targets
Related Tools
How to Use This Tool
- What to Enter
- Enter a hostname or IP address to scan for open TCP ports.
- What You Get
- Lists open, closed, and filtered ports with detected service names.
How to Interpret Results
Open ports indicate running services. Unexpected open ports may signal security risks. Filtered ports suggest a firewall is blocking access.
Common Issues & Troubleshooting
Firewalls may block scan traffic, showing all ports as filtered. Cloud providers may rate-limit port scans. Some ports may appear closed but respond to specific protocols.