#!/bin/bash
HOST='ftp://windows.server:21'
USER='myuser'
PASS='mypass'
TARGETFOLDER='/linux-server-folder'
SOURCEFOLDER='/windows-server-folder'

lftp -f "
set ftps:initial-prot ""
set ftp:ssl-allow true
set ftp:ssl-force true
set ftp:ssl-protect-data true
set ftp:ssl-protect-list true
set ssl:verify-certificate true
open $HOST
login $USER $PASS
lcd $SOURCEFOLDER
"