📖 Description

Since servers are typically deployed in data centers or the cloud, conducting an "external health check" is crucial:

Verify Firewall Policies: Confirm whether the port blocking rules you set on cloud platforms (e.g., Alibaba Cloud Security Groups, AWS SG) are truly effective.
Troubleshoot Application Connectivity: When unable to access a website or database, use scanning to confirm if ports like 80, 443, or 3306 are blocked by your ISP or firewall.
Identify Exposure Risks: Check if any ports that should not be public (e.g., Redis 6379, RDP 3389) are exposed to the internet due to misconfiguration.
Service Availability Monitoring: Quickly confirm if specific services on a remote server (e.g., port 25 for a mail server) are running.

This site's port scanner provides comprehensive support from "Quick Scan" to "Deep Customization":

Quick Scan for Common Ports: One-click detection of the top 20 most commonly used service ports (e.g., 21, 22, 80, 443, 8080).
Custom Range Scan: Supports specifying specific port numbers (e.g., 3000, 9000) or port ranges (e.g., 1-1000).

Open: The target port responds well, and the service is accessible.
Closed/Filtered: The target port refuses the connection or is blocked by a firewall, with no response.

The tool has a built-in port-to-service mapping table. Common service names (e.g., SSH for port 22) are automatically annotated in the scan results.

Genuine External Perspective: Scan requests are initiated from this site's cloud servers, simulating the access path of a real hacker or external user. The results are more valuable for reference than local localhost testing.

Enter Target: Input the target server's IP address or domain name (e.g., 123.123.123.123 or example.com) in the address field.
Set Ports: * Select "Common Ports" for an instant report.
- Or enter specific ports in the custom field, separated by commas.
Start Scan: Click the "Start Probe" button.
View Results: The results list will display the port number, status, and corresponding service suggestion in a table format.
Security Assessment: If unexpected open ports are found, immediately log into the server to harden the firewall.

Port Number	Common Service	Security Recommendation
21	FTP	Recommend closing; use SFTP (22) instead.
22	SSH	Recommend opening only to specific IPs to avoid brute-force attacks.
80 / 443	HTTP / HTTPS	Essential for websites; ensure SSL is configured.
3306	MySQL	High Risk! Never expose fully to the public internet; recommend internal network access only.
6379	Redis	Extremely High Risk! Must set a strong password and bind to a private IP.

Legal Use Only: This tool is intended solely for scanning servers you own or targets for which you have explicit authorization.
Scan Frequency: To prevent the target server from misinterpreting scans as attacks, this tool implements reasonable scan frequency limits.
Firewall False Positives: Some advanced firewalls may identify and block scan requests, resulting in a "Closed" status. Please assess results in conjunction with your actual business situation.

Port Scanner