Choosing a protocol

linscp talks to five kinds of servers. You pick one in the File protocol box of the Site Manager. Your server usually decides for you: use what it offers, and prefer an encrypted option when there is a choice.

Quick comparison

Protocol	Encrypted	Default port	Pick it when
SFTP	Always (SSH)	22	The server runs OpenSSH or another SSH server. The best default.
SCP	Always (SSH)	22	The SSH server has no SFTP subsystem.
FTP	No	21	Only on a trusted network, or for public anonymous downloads.
FTP with TLS/SSL	Yes	21 or 990	The host offers FTP only, but supports FTPS.
WebDAV	Optional (HTTPS)	80 or 443	The files sit behind a web server, such as Nextcloud or Apache mod_dav.
Amazon S3	Usually (HTTPS)	443	You store objects in AWS S3 or an S3-compatible service.

SFTP

SFTP runs inside an SSH connection. Logins, file data and listings are all encrypted, and the server’s identity is checked with its host key. It supports permissions, ownership, symbolic links, resumable transfers and server-side renames. If you are not sure what to pick, pick SFTP.

SCP

SCP also uses SSH, but linscp drives it through the remote shell: it runs commands such as ls and scp and reads their output. That makes it sensitive to the shell’s startup scripts and to unusual ls output. Use it only when SFTP is not available. With SFTP selected, linscp can switch to SCP by itself when the SFTP subsystem is missing; see Allow SCP fallback in SSH, SFTP and SCP settings.

FTP and FTPS

Plain FTP sends your password and your files in clear text. With FTP chosen, the Encryption box offers two TLS variants:

• TLS/SSL Explicit encryption connects on the normal FTP port and then asks the server to switch to TLS. This is what most servers expect.
• TLS/SSL Implicit encryption starts TLS at once, normally on port 990. It is an older style.

FTP opens a second connection for each listing and transfer, which is where passive and active mode matter. See FTP and FTPS settings.

WebDAV

WebDAV extends HTTP with file operations. Choose TLS/SSL Implicit encryption in Encryption to use HTTPS; without it, everything travels unencrypted. WebDAV servers can lock files, and linscp can show and set those locks. See WebDAV and S3 settings.

Amazon S3

S3 stores objects in buckets rather than files in directories. linscp shows buckets as top-level folders and object key prefixes as subfolders. Your S3 credentials (an access key ID plus a secret access key) replace the user name and password, or linscp can read them from your AWS environment. Many other storage services speak the S3 API too; give their endpoint as the host name.

Protocols in session URLs

Each protocol has a URL scheme, used on the command line, in the Open URL box and by links in a browser: sftp://, scp://, ftp://, ftps:// (implicit TLS), ftpes:// (explicit TLS), dav://, davs:// and s3://. An ssh:// URL opens SFTP. See Session URLs for the full syntax.