Softonic

Open Port Scanner

Step 1 / 2 Host
Only scan hosts you own or have explicit permission to probe. The scan checks ~20 well-known TCP ports.
Next

Enter a hostname or IP and this scanner tries to open a TCP connection to a fixed list of 18 well-known ports, from SSH and the web ports to the common mail and database ports, and reports which ones accept a connection (are open). It is a quick, light-touch check for confirming that an SSH box is reachable, a site is answering on 443, or a firewall rule really does block what it should. It only reaches public internet hosts and does not probe custom ports, so treat it as a fast sanity check, not a replacement for a full scanner like nmap.

How the scanner checks ports

  1. 1

    Enter a public host

    A hostname or IP on the public internet. Private, loopback and reserved addresses are rejected, and there is no custom port field: the 18 ports are fixed.

  2. 2

    TCP connect probe

    The scanner opens a TCP connection to each of the 18 ports from a shared public source address, with a short timeout (about 2 seconds) per port.

  3. 3

    Collect the open ports

    A port that accepts the connection is recorded as open. Ports that are closed, filtered or on an unreachable host are skipped; this basic scan does not tell those cases apart.

  4. 4

    Read the list

    Each open port is shown with its usual service name, for example 22 as SSH or 443 as HTTPS.

The ports this scanner checks

This basic scanner probes a fixed list of 18 well-known ports, all over TCP. You cannot add your own.

Port Service
21 FTP
22 SSH
23 Telnet
25 SMTP
53 DNS
80 HTTP
110 POP3
143 IMAP
443 HTTPS
465 SMTPS
587 SMTP (submission)
993 IMAPS
995 POP3S
3306 MySQL
5432 PostgreSQL
6379 Redis
8080 HTTP-alt
8443 HTTPS-alt

How to read the result

The scanner lists only the ports that accepted a TCP connection, the open ones, each with its usual service name. A port that is closed, filtered by a firewall, or on an unreachable host simply does not appear: this basic scanner does not tell those cases apart. An empty result means none of the 18 ports accepted a connection (or the host was unreachable), which for a hardened host is the expected, safe outcome.

Public hosts only

The scan runs from a shared public source address and only accepts public internet hostnames or IPs. Private, loopback and reserved ranges (for example 127.0.0.1, 10.x, 192.168.x, ::1) are rejected, so you cannot use it to reach machines inside your own LAN. Run a scanner on your own network for that.

Legitimate vs problematic uses

Scanning your own hosts, or hosts you have explicit written permission to test, is routine operations work. Scanning someone else’s host is a different matter:

  • It is often lawful in the US under Computer Fraud and Abuse Act case law, as long as you do not attempt to exploit anything, but this is not legal advice.
  • It can breach the terms of service of many cloud providers and ISPs.
  • It is a criminal offence in some jurisdictions (the UK Computer Misuse Act, for example, treats unauthorised access broadly).
  • It is always logged. The target records the connection attempts with your source IP and a timestamp.

Defensive notes

An open port is not automatically a way in: the service behind it may still require authentication. Modern hosts pair a closed-by-default firewall with authenticated services, so a scan reveals reachability, not access. If you find an unexpected open port on your own host, check which service is bound to it and whether it should face the internet at all.

Tips

  • Scan from outside your network. An internal scan misses the firewall and NAT rules that shape what the public internet actually sees.
  • Keep it to hosts you are allowed to test. Never point a scanner at third-party infrastructure without permission.
  • This is a basic TCP check. It does not cover UDP, custom ports, service-version detection or OS fingerprinting. Use a full local scanner such as nmap when you need depth.

Frequently Asked Questions

Scanning your own hosts is unambiguously legal in most jurisdictions. Scanning hosts you do not own sits in a grey zone: rarely prosecuted as long as no exploit follows, but often against the terms of service of cloud providers and ISPs, and a criminal offence in some countries. This is general information, not legal advice.

This scanner lists only ports that accept a TCP connection. If a port you expected is missing, it is closed, filtered by a firewall, or the host was unreachable. This basic tool does not label the reason, and it only checks its fixed set of 18 ports, so a port outside that list is never tested at all.

This tool opens a plain TCP connection to a fixed list of 18 ports from a shared public address and reports only the open ones. Nmap is a full scanner: custom and full port ranges, UDP, the closed-versus-filtered distinction, service-version and OS detection, stealth modes and scripting. Use this for a quick reachability check; run nmap locally when you need depth.

Because your router almost certainly uses NAT and forwards nothing inbound. Unless you deliberately set up port forwarding, incoming connections from the internet are blocked at the router, so the scan finds nothing open. That is the default, safe state.

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