What is a Port Scanner?
A port scanner scans a host by name or address to find out which ports are open, closed or filtered. A communication endpoint (like port 80 for HTTP, port 443 for HTTPS, port 22 for SSH, and so on) on which different services run.
Our Port Scanner is used to connect to a list of common ports used and report if they are accepting connections. It is a fast method to test the reachability of a service, confirm the firewall rules, or troubleshoot connecting to a service.
Which Ports Does the Scanner Scan?
The tool scans ports number 12 such as:
- Port 21 — FTP — File transfer.
- Port 25 — SMTP — Simple mail transfer protocol for sending emails.
- Port 25 — SMTP — Send Email
- Port 53 — DNS — Hostname resolution.
- Port 80 — HTTP — Web traffic.
- Port 110 — POP3 — Retrieval of email.
- Port 143 — IMAP — Email access.
- Port 443 — HTTPS — Encrypted Web traffic.
- Port 8080 — Web server — Database server.
- Port 3389 — RDP — Windows remote desktop.
- Port 8080 — HTTP Alt — Alternate Web server port.
- Port 8443 — HTTPS Alt — Alternative secure web services.
Using the Port Scanner:
- Enter a hostname (e.g. example.com) or an IP address.
- Click Scan Ports.
- Review results – each port will be displayed as Open or Closed.
Port Scan Results
- Open — A service is listening, accepted the connection. The service can be accessed from the scanner's location.
- Closed — No service is listening or a firewall is denying access.
We set the timeout to 2 seconds per port with our tool. A silent firewall that drops packets will display ports as closed as the connection will not timeout, because nothing is received.
What is the purpose of Open Ports check?
Services need to be open at least in order to work, but any open port that isn't necessary is a potential attack surface. Here are some of the benefits of regular port scanning:
- Verify services — Ensure that the web, mail, or database servers are “listening” on the appropriate port numbers.
- Identify unauthorized services — Identify services running on unexpected ports.
- Check Firewall Rules — Ensure Firewalls allow and deny correct ports.
- Troubleshoot connectivity — Indicate if a service is down or blocked at the network level.
- Security auditing — Only allow the necessary ports to be exposed to the Internet.
There are some tips to keep in mind when dealing with open ports.
- Close unnecessary ports—Any port that is not being used by an active service should be closed or firewalled.
- Use strong authentication — SSH (22) and RDP (3389) should use key-based authentication, strong password and IP restrictions.
- Update services — Update any services that are vulnerable to attack or are exposed.
- Monitor regularly — Conduct scheduled port scans to detect any changes where they don't need to be.
Privacy
Our Port Scanner makes direct TCP connections from our server to the target host. No scan results, hostnames or IP addresses are saved, logged or shared. There are no accounts, rate limits, or captchas.
Frequently Asked Questions
What is a port?
A port is a numbered endpoint (0 to 65535) which allows different services on a common host to be distinguished. An IP address and a port number specify a particular service, such as the 192.168.1.1:80 web server.
Is the port scanner free of any cost?
Yes. There are no limits, sign-up, captchas or anything else at all. Scan the number of hosts you require.
What does open/closed mean?
Open indicates that the TCP connection was accepted by the service, Closed indicates that the TCP connection was refused, timed out or no service was listening. A silent drop firewall will also cause ports to appear as closed.
What is the mechanism of action of the tool?
It tries to connect to all ports of the target host with the PHP fsockopen function. Successful connections are reported as open and timed out/failed connections are reported closed. No third party APIs are utilized.
Why only 12 ports?
A web-based tool would not be capable of performing a complete scan of all 65,535 ports, and would consequently not be able to identify all of the hidden ports. Here are the 12 most popular services. To get a thorough report on the status of a system use command-line tools, such as nmap.
Is it possible to scan my own server?
Yes. A typical use case for scanning is to ensure that only intended services are exposed when scanning own servers and network.
Is it OK to scan?
It is generally okay to scan your own hosts. Hosts that are not scanned or to which you do not have permission to scan may be scanned in violation of network terms of service. Never scan any host without permission.