Re: ange-ftp and explicit/implicit TLS

[Eli Zaretskii]

> From: "David Diem" <david.diem@uni-konstanz.de>
> Date: Sat, 26 Dec 2020 20:35:09 +0100
> 
> I'm trying to connect to a FTP server that requires TLS -- that is, FTPS. I 
> learned that /bin/ftp cannot do this, so I changed ange-ftp-ftp-program-name 
> to lftp. Ange-ftp still responds with "550 - TLS required on the control 
> channel". In a shell outside of emacs, "lftp myuser@myserver.com" can 
> succesfully log in (the TLS information is given on stdout) -- however, that 
> is not the case for the command "lftp myserver.com" (without the "user@") and 
> a subsequent "DIR" or similar. The difference of the non-emacs (non-ange-ftp) 
> shell's output differs to that of ange-ftp in that the first says "AUTH TLS" 
> at an early point.
> 
> Is this what is called explicit TLS? How could one tell ange-ftp to say "AUTH 
> TLS" early on? My real question, though, is why do the outputs of ange-ftp 
> and non-ange-ftp "plain" lftp differ anyway? As I understand the 
> ange-ftp-name-format regexp, ange starts by saying something in the form of 
> user@server.com, that is, it does include the user right form the beginning.

If you look at defcustoms in ange-ftp.el, you will see that it allows
to customize the name of the program to use; "ftp" is just the
default.  Maybe this will help you solve your problem.