extensions

SFTP protocol extensions the server advertised as extension-name/extension-data pairs trailing its SSH_FXP_VERSION reply (draft-ietf-secsh-filexfer-02 section 3). Only the names are kept; extension-specific data (if any) is discarded.

Common OpenSSH extensions found here: "copy-data" (see copyData), "posix-rename@openssh.com", "hardlink@openssh.com", "fsync@openssh.com", "statvfs@openssh.com". Empty if the server advertised none (or a server this old predates extensions entirely).