Online Port Scanner: Which Ports Can It Check? (Safe Usage Tips)

In daily website security checks, server maintenance, and network troubleshooting, whether a port is open is often the first point many people want to verify.

So, what ports can online port scanning actually detect? Can it only scan common ports? Is full port scanning possible? How accurate is it?

Next, we will explain in detail which ports online port scanning tools can detect and how to use them more safely!

1.Which Ports Can Online Port Scanning Detect?

1. Common Port Quick Scan (Most Frequent)

This mainly targets the most commonly used basic service ports on the Internet, such as:

• 80 / 443 Website HTTP/HTTPS

• 21 / 22 FTP / SSH

• 25 / 465 / 587 Email SMTP

• 3306 MySQL

• 6379 Redis

• 8080 / 8443 Common web service extension ports

• 53 DNS

• 3389 Windows RDP Remote Desktop

This type of scan is fast, low-risk, and most suitable for basic checks by regular users.

2. Full Port Scan (1-65535)

Some professional platforms offer full port scanning, which can detect all TCP ports and even partially support UDP scans. However, because full port scans take longer and may be misidentified as abnormal traffic by certain security policies, they are more suitable for security administrators or developers to use within authorized scope.

2. What is the underlying logic of online port scanning tools?

Simply put, port scanning sends a series of network requests to the target IP to see if there is a response.

• If the port is open, handshake information or service identifiers are returned.

• If the port is closed, a connection refusal or timeout occurs.

• If blocked by a firewall, it may show as "filtered" or "no response."

Essentially, it is not mysterious; it is a network-level probing method.

3. Browser Detection + Fingerprinting: Modern Tools Are More Powerful Than You Think

Modern security tools go beyond simple "port scanning." The ToDetect fingerprint detection tool can not only check port services but also identify:

• Visitor’s browser type, system version, IP location, and whether a proxy/accelerator is used.

• Whether WebRTC, Canvas, or font rendering features are enabled, which is valuable for development debugging and security inspections.

4. What Scenarios Are Suitable for Online Port Scanning?

1. Checking if server ports are exposed

For example, after creating a cloud server, you may want to verify whether port 22 is correctly open, and whether ports 80 and 443 are functioning properly.

Are Redis or MySQL unintentionally exposed to the public network? Online port scanning can let you check this with one click.

2. Website Troubleshooting

When a website is inaccessible, you can scan port 80 to see if it is open and check whether reverse proxy ports are functioning.

Confirming whether the database is blocked is much more efficient than blindly troubleshooting.

3. Self-Check Before Security Hardening

During security inspections, organizations or individuals can compile a list of open ports:

Are there unnecessary ports, leftover services, or potential security risks? Simple but very important.

4. Network Anomaly Detection

When a remote service connection fails, scanning can help determine whether the issue is a port problem, an IP restriction, or firewall blocking.

5. How to Choose a ReliableOnline Port Scanning Platform?

• Does it support common port quick scans?

• Does it provide full port scanning functionality?

• Does it include browser detection, fingerprinting, and other extended features?

• Is the scanning speed stable?

• Does it specify that data will not be saved or leaked?

• Does it support HTTPS, IPv6, TCP/UDP, and other modes?

Some platforms integrate port scanning + browser detection + fingerprinting, such as the ToDetect tool series, making the inspection process more efficient.

Summary:

Online port scanning not only quickly checks the status of common ports but also works with browser detection and fingerprinting tools (such as ToDetect fingerprint detection tool) to thoroughly uncover the basic information of servers and websites.

Whether you are a developer, cross-border e-commerce operator, or a regular user, online scanning is the fastest way to check ports or troubleshoot network issues.