In this article, we'll see how to enable passive ports on an FTP server using Microsoft IIS FTP Server. Passive mode is essential to allow FTP connections, especially if the server is behind a firewall. For this guide, we'll use Windows Server 2025 Datacenter, but the process is similar in other Windows Server versions.
Configure Passive Port Range in IIS
Access Server Manager, click Tools in the top-right corner, and select Internet Information Services (IIS) Manager from the dropdown menu:
A new window will open. Select your server in the left-side panel and double-click the FTP Firewall Support icon:
In the Data Channel Port Range field, enter your desired port range (e.g., 49152-65534), and in External IP Address of Firewall enter your server's public IP. Click Apply to save changes:
Note
The valid port range is 1024-65535 (ports 1-1023 are reserved for system services). However, we recommend using a narrower range within this interval, e.g., 50000-51000, to enhance security and simplify firewall management.
Restart FTP Service
To apply configuration changes, restart the FTP service. Open the services console by pressing Win+R and typing services.msc. Click OK:
The Services window will open. Locate and select Microsoft FTP Service in the services list, then click Restart:
After configuring the IIS firewall settings and restarting the service, you must also open the same port range in the Clouding firewall:
Following these steps, your server will now accept passive FTP connections in your IIS FTP server.
Important
Windows Server includes a built-in firewall. If enabled, remember to configure it as well.
We hope this article has been helpful! 🙂 Remember, if you have questions about this or any other Clouding server-related matter, feel free to contact us at support@clouding.io We're here to help with anything you need!