Azure Ubuntu FTP Server: A Step-by-Step Guide to Setting Up a Secure FTP Connection

In today's digital landscape, securing file transfer protocol (FTP) connections is crucial for businesses and organizations that rely on data transmission over the internet. Azure provides a robust security framework to ensure the integrity of your FTP server, but setting up a secure connection can be challenging, especially when dealing with existing infrastructure. This article will guide you through the process of configuring an Azure Ubuntu FTP server, highlighting the importance of DNAT rules, NSGs, and Azure Firewall configuration.

To begin, I checked the Azure Firewall DNAT rules, ensuring they were in place and correct. However, directory listing issues persisted in about 50% of cases when browsing through folders. To troubleshoot this issue, I used WinSCP as an FTPS client, but the problem remained. Subsequently, I switched to Filezilla FTP client and tested Explicit FTPS connectivity, which initially worked smoothly.

After fixing IP configuration issues with the FTP site, I was ready to configure NSGs and Azure Firewall with necessary rules. This involved storing the original FTPS virtual machine (FTP via IIS on Windows Server 2022) in Azure using Veeam Backup and Recovery V12. The process is documented in the Inbound DNAT (FTP client on Internet, server in VNet) section of Microsoft's official documentation.

In this setup, the FTP server runs behind the Azure Firewall (a Secured Hub in Azure VWAN), with the client on the internet. This configuration falls under the Outbound VNet – Internet (FTP client in VNet, server on Internet) section of the Microsoft docs.

The key takeaway from this experience is the importance of configuring the FTP server to accept data and control channels from different source IP addresses. As confirmed by official Microsoft documentation, this requires DNAT rules for port 21 and the chosen port range for the FTP data channel.

Azure Firewall supports passive FTP over SSL, which can be achieved through a specific configuration. A quick internet search reveals that Azure Firewall does indeed support passive FTP, making it an ideal solution for organizations that require secure file transfer protocols.

In conclusion, setting up a secure Azure Ubuntu FTP server requires careful planning and configuration of DNAT rules, NSGs, and Azure Firewall settings. By following this guide, you can ensure a robust and secure FTP connection for your organization's data transmission needs.

Azure ubuntu ftp server