How do I get lftp to use SSL/TLS security mechanis

Question

I'm trying to log into an ftps site. I've tried giving the login creds at the command line (and putting set parameters in ~/.lftprc, then opening an lftp session and typing those parameters with lftp job control statements. Regardless, I keep hitting the same roadblock:

 421 Sorry, cleartext sessions are not accepted on this server.
 Please reconnect using SSL/TLS security mechanisms.

I got furthest with the following parameters, but keep getting the error above.

How do I get lftp to use SSL/TLS security mechanism from the command line?

The objective is to script the access to this ftps site using bash (programming without using expect).

 lftp
 lftp :~> set ssl-allow false
 lftp :~> set passive-mode yes
 lftp :~> open ftp.abc.com
 lftp ftp.abc.com:~> login theuser
 Password:
 lftp [e-mail]:~> cd
  `cd' at 0 [Delaying before reconnect: 26]
 CTRL-C
 lftp [e-mail]:~> debug
 lftp [e-mail]:~> cd
 ---- Connecting to ftp.abc.com (XX.XXX.XX.XX) port 21
 <--- 220-Welcome to the Yahoo! Web Hosting FTP server
 <--- 220-Need help? Get all details at:
 <--- 220-http://help.yahoo.com/help/us/webhosting/gftp/
 <--- 220-
 <--- 220-No anonymous logins accepted.
 <--- 220-Yahoo!
 <--- 220-Local time is now 15:30. Server port: 21.
 <--- 220-This is a private system - No anonymous login
 <--- 220 You will be disconnected after 5 minutes of inactivity.
 ---> FEAT
 <--- 211-Extensions supported:
 <---  EPRT
 <---  IDLE
 <---  MDTM
 <---  SIZE
 <---  MFMT
 <---  REST STREAM
 <---  MLST type*;size*;sizd*;modify*;UNIX.mode*;UNIX.uid*;UNIX.gid*;unique*;
 <---  MLSD
 <---  XDBG
 <---  AUTH TLS
 <---  PBSZ
 <---  PROT
 <---  TVFS
 <---  ESTA
 <---  PASV
 <---  EPSV
 <---  SPSV
 <---  ESTP
 <--- 211 End.
 ---> OPTS MLST type;size;modify;UNIX.mode;UNIX.uid;UNIX.gid;
 <--- 200  MLST OPTS type;size;sizd;modify;UNIX.mode;UNIX.uid;UNIX.gid;unique;
 ---> USER theuser
 <--- 421 Sorry, cleartext sessions are not accepted on this server.
 Please reconnect using SSL/TLS security mechanisms.

Answer 1

lftp version must be >= 4.6.3 (Debian user)