Netstat is a command-line utility available on Windows operating systems that allows you to display information about network connections, routing tables, interface statistics, masquerade connections, etc. You can use netstat -ano to see active network connections and their associated process IDs (PIDs), which can help you identify potential rogue connections to your machine.
Here’s a step-by-step tutorial on how to use netstat and the most common switches (-ano).
Step 1: Open Command Prompt
- Press
Win + Rto open the Run dialog. - Type “cmd” and press Enter to open the Command Prompt.
Step 2: Run netstat -ano
In the Command Prompt window, type the following command and press Enter:
netstat -ano
This command will display a list of active network connections and associated PIDs.
Step 3: Analyze the Output
The output of netstat -ano will have several columns:
- Proto: Indicates the protocol used (e.g., TCP, UDP).
- Local Address: Shows the local IP address and port.
- Foreign Address: Displays the remote IP address and port.
- State: Shows the state of the connection (e.g., ESTABLISHED, TIME_WAIT).
- PID: Indicates the Process ID associated with the connection.
Here’s how to analyze the output:
- Look for any unfamiliar or suspicious IP addresses in the “Foreign Address” column. These could potentially be rogue connections.
- Check the “State” column to see if any connections are in unusual states (e.g., TIME_WAIT for a long time).
- Identify the PID associated with each connection in the “PID” column. You can cross-reference this PID with the Task Manager to determine which process is responsible for the connection.
Step 4: Investigate Suspicious Connections
If you find any connections that you suspect are rogue or unwanted, take the following actions:
- Identify the Process: Use the PID from the “PID” column to locate the associated process in Task Manager. Right-click the Taskbar, select “Task Manager,” go to the “Details” tab, and find the process with the matching PID.
- Research the Process: If the process is unfamiliar or suspicious, research it online to determine if it’s legitimate or potential malware. Be cautious before terminating any processes.
- Terminate Suspicious Processes: If you’re certain that a process is malicious or unwanted, you can end the process in Task Manager by right-clicking the process and selecting “End Task.” However, exercise caution, as terminating critical system processes can cause system instability; know what you’re doing.
- Firewall and Antivirus: Ensure that you have a firewall and antivirus software installed and updated. They can help detect and block unwanted network connections and malware.
For more switches and details, visit Microsoft’s documentation on Netstat here. You may also like our article on detecting malware on your machine.
