sftpserver

An sftpserver is a server that provides access to files using the Secure File Transfer Protocol (SFTP), which runs over the SSH protocol. It enables secure transfer, listing, and management of files between a client and the server. Unlike FTP, SFTP encrypts both commands and data, helping protect credentials and sensitive information in transit.

SFTP is typically implemented as a subsystem of an SSH daemon. A client connects on port 22, authenticates via password or public-key authentication, and then issues file-related commands that are translated by the SSH server into file system operations. Many servers run a dedicated sftp-server binary or an internal SFTP subsystem to isolate and sandbox the file operations.

In common deployments, the OpenSSH server provides SFTP via the internal-sftp or sftp-server binaries configured in sshd_config. Administrators may restrict access with chroot jails and per-user restrictions using Match blocks, set file permissions, and enable logging. SFTP servers can enforce quotas, access controls, and directory restrictions to limit user exposure.

Other implementations exist for different platforms, including commercial and open-source SSH servers and specialized appliances. For Windows, OpenSSH can be installed, and third-party tools can provide SFTP functionality. Some environments use SFTP alongside other protocols or use alternatives like FTPS or SCP for file transfers.

Security considerations include using strong authentication (preferably public-key), disabling password logins when possible, keeping the SSH server updated, enabling audit logging, and restricting users to necessary directories. Sftpservers are commonly used for remote backups, automated deployments, and secure file exchange between organizations.