FTP and FTPS support in SFTPPlus MFT

SFTPPlus as an FTP Server ​

SFTPPlus can function as a secure and reliable FTP server, allowing external clients to connect and exchange files. The solution supports a range of FTP security levels:

• Legacy FTP: Unencrypted FTP for environments where security is not a primary concern or for compatibility with older systems.
• Implicit FTPS: The entire connection is secured with TLS (Transport Layer Security) from the outset, typically on a dedicated port.
• Explicit FTPS: The connection starts as a plain FTP session, and the client explicitly requests a secure connection using the AUTH TLS command.

All secure FTP transfers are protected by TLS, ensuring the confidentiality and integrity of data in transit. SFTPPlus supports both active and passive FTP transfer modes, accommodating various network configurations and firewall rules.

Customize the FTP and FTPS identity ​

The welcome banner shown when an FTP or FTPS client connects can contain any text. It can display an authorized-use notice, a partner-specific greeting, or an organization's own service name without identifying SFTPPlus.

SFTPPlus does not include its product version in the FTP protocol handshake. Together, these controls reduce software fingerprinting and support white-labelled transfer services.

SFTPPlus as an FTP Client ​

For SAP workflows, SFTPPlus can collect partner files into an import folder or deliver SAP exports to a remote FTPS server. See the SAP file transfer guide for the shared SFTP and FTPS workflow, SOAP notifications, and licence choices.

In addition to its server capabilities, SFTPPlus can act as an FTP client. This functionality enables automated file transfers to and from remote FTP servers. Users can configure SFTPPlus to automatically upload or download files on a schedule or based on specific events. The client-side support mirrors the server-side security features, including connections to both legacy FTP and secure FTPS servers.

Handle private addresses in passive FTP responses ​

In passive mode, an FTP server uses its PASV response to advertise the IP address and port for the data connection. Some legacy servers behind network address translation advertise a private IP address that is not reachable by the SFTPPlus client. SFTPPlus can ignore that address and connect to the address used for the FTP command connection instead.

Other environments deliberately advertise a different private IP address, for example when an internal load balancer routes the data connection. For these deployments, SFTPPlus can be configured to accept and use the IP address from the PASV response.

Directory Listings Built for Automation ​

The traditional FTP LIST command returns directory information intended for people, without a single standardized format. SFTPPlus avoids fragile parsing when modern FTP commands are available.

As a server, SFTPPlus supports the RFC 3659 MLSD and MLST commands to provide standardized, machine-readable directory and file information. As a client, it can use MLSD for directory listings and MLST for individual paths when the remote server supports them, then fall back to LIST when necessary.

When connecting to older servers, the SFTPPlus client recognizes both Unix-style and MS-DOS-style LIST responses. It handles common MS-DOS variations, including localized date formats and dates that use either two-digit or four-digit years. This allows automated transfers to process listings from a wider range of legacy FTP and FTPS servers.

Authentication and Security ​

Security is a core component of SFTPPlus's design. For FTP and FTPS transfers, SFTPPlus provides multiple authentication methods:

• Username and Password: Standard authentication using credentials.
• Mutual TLS Authentication: A higher level of security where both the client and the server verify each other's identity using digital certificates. This prevents man-in-the-middle attacks and ensures only trusted parties can connect.
• Password and TLS certificates for highly sensitive transfers.

Load Balancer Integration ​

SFTPPlus is designed to operate effectively behind a load balancer, providing scalability and high availability for your file transfer services. A key feature is its ability to handle passive FTP connections in a load-balanced environment. To manage this, SFTPPlus keeps the passive port connections on each node in the load balancer. This ensures that passive mode data connections, which are crucial for many FTP transfers, are correctly routed to the appropriate server instance, maintaining session integrity and performance. This capability is essential for large-scale deployments where traffic must be distributed across multiple servers to handle high volumes of transfers.

File Transfer Bridging Capabilities ​

SFTPPlus's client functionality allows it to act as a protocol bridge, facilitating automated file transfers between different systems. This means SFTPPlus can be configured to move files from a source server using one protocol to a destination server using FTP or FTPS. For example, a transfer task can be set up to:

• Download a file from an SFTP server and upload it to an FTP server.
• Retrieve documents from a Web server (HTTP/S) and transfer them to an FTP location.
• Synchronize data from Azure Blob Storage to an FTP server.
• Migrate files from SharePoint Online to a remote FTP site.
• Process email attachments from an email server and deliver them to a specific FTP directory.

This bridging capability simplifies complex data workflows by centralizing them within a single MFT solution, eliminating the need for custom scripting or multiple applications.

Get help from experts for implementation or migration ​

SFTPPlus MFT offers complete and secure support for the FTP protocol, making it a versatile solution for a wide range of file transfer needs. It provides the flexibility to support legacy systems while also meeting modern security requirements through its robust implementation of FTPS and mutual TLS authentication.

With over 20 years of experience, our support team has successfully assisted our customers in implementing secure FTP transfers and migrating from legacy FTP to modern FTPS, SFTP, or cloud-based solutions.

If you are looking to secure legacy systems, bridge different protocols, or scale your transfers with a load-balanced architecture, our team is ready to assist.

Contact us to discuss how SFTPPlus can be tailored to meet your specific file transfer requirements and help you implement a robust and reliable solution.