Port Scanner
Scan the TCP ports of one host from your computer: a common list, 1–1024, all 65535 or your own ranges.
The scan runs on your computer through the local agent. The host and the results stay on this page.
Scan
Agent disconnectedConnection settings
Local agent
The connection is remembered in this browser until the session expires or the agent restarts. Disconnect removes it.
Set up the agent
Download and start the local agent, then come back to this page.
About the agent and download- Start MyDevTools Agent. To scan a private or loopback address, turn on “Allow local network and this PC as targets” in the agent window.
- Copy the pairing code from the agent window.
- Paste the code below. If the browser asks for local-network access, allow it for this connection.
The browser sends the host, the port list and the timeout only to the agent on 127.0.0.1. The agent opens TCP connections to that one host and closes each one at once. It sends no data and reads no banners. The scan does not go to a MyDevTools server. This browser remembers the preset, your port list, the timeout and the parallel count. It does not store the host or the results.
Results
Scan a host to see its ports.
| Port | Usual service | Status | Time |
|---|
On this page
Port Scanner asks the local agent on your Windows computer to try TCP connections to one host and reports each port as open, closed or filtered. Choose 70 common service ports, the well-known range 1–1024, all 65535 ports or your own list of ports and ranges. Results stream in as the scan runs, and Stop ends it in the agent. The grant is port.scan, separate from tcp.connect and the other network tools.
Detailed Functionality
This is a connect scan: the agent completes the TCP handshake and closes the socket at once, without sending data or reading a banner. A refused connection is closed, no answer within the timeout is filtered, and no route is unreachable. Up to 64 connections run at once, and each port waits 200 to 5000 milliseconds. For up to 1024 ports every port is listed; for a larger scan only the open ones are, with counts for the rest. The agent applies the same destination rules as its other tools: private and loopback addresses only when “Allow local network and this PC as targets” is on in the agent window, metadata, link-local and multicast addresses never, and its own listening port is shown as blocked. At most two scans run at once. Scan only hosts you own or are allowed to test.
Practical Examples
127.0.0.1with the common list shows what is listening on your own PC (turn on local-network access in the agent window first).192.168.1.1with 1–1024 lists the services your router exposes.example.comwith80, 443, 8080-8090checks a web server and its alternate ports.
How to Use This Tool
Start the local agent
Download the agent, start it, and copy the pairing code.
Pair the port scanner
Paste the code and connect. The page asks for port.scan and keeps capabilities this browser already holds.
Choose the host and ports
Enter one host, pick a port preset or type your own list, and set the timeout and the parallel count.
Scan and read the results
Press Scan. Open ports appear as they are found with their usual service. Press Stop to end early, and copy the results as text.
Tips and Best Practices
- Filtered usually means a firewall drops the packets. A longer timeout tells a slow host from a filtered port.
- A full 1–65535 scan with a 1000 ms timeout can take several minutes against a filtered host; lower the timeout for a host on your own network.
- The usual service is the port's common assignment, not what the host actually runs.
- The published Windows download may be older than this page. The scanner needs an agent that advertises port.scan.