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WinSCP Supported Transfer Protocols
Since version 3.0, WinSCP supports two secure transfer protocols, SFTP and SCP. Currently, many of the SSH servers support both protocols. Either of them have both advantages and disadvantages. This document contains their comparison to help you to decide which is most appropriate for your needs. The comparison lists either features that are characteristic to the specific protocol as-is, or features that are caused by the implementation of the protocol in WinSCP.
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The default mode of operation is to use SFTP and fall back to SCP. Both protocols have advantages and disadvantages.
SCP (Secure Copy Protocol)
SCP is mostly used with SSH1. SCP is an older protocol but almost universally supported as part of an SSH protocol suite. SCP is a descendant of the ancient “rcp”.
Protocol itself allows only file transfers in both directions. Other features of WinSCP are realized using common shell commands, like cd, ls, pwd, rm, ln, etc. For this, WinSCP, unlike command-line SCP clients, which allow only file transfers, requires full shell access and permission to execute other commands in addition to scp (see requirements). For access to non-UNIX operation system, it is necessary to have at least UNIX-like shell. One like that is for example available with OpenSSH for Windows.
SFTP (SSH File Transfer Protocol)
SFTP is mostly operated as subsystem of SSH2. SFTP is a newer and more modern protocol, designed to perform in a manner similar to FTP. It is widely supported, but not nearly as universally so as SCP.
WinSCP supports version 0 (since 3.4), version 1 (since 3.4), version 2 (since 3.1), version 3 (since 3.0 beta), version 4 (since 3.2) and version 5 (since 3.6.7) of the protocol. Support for version 5 is experimental as no server supporting the version is known and currently does not bring any new functionality. Unlike SCP, for connection with SSH server, you do not need access to shell. Thus it is more independent on remote operation system.