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I needed to set up an FTPS server.

After trying a couple of servers and not having any joy I asked on #debian and was recommended to try ProFTPD.

It's easy to configure and does all the things we needed...

NOTE: FTPS is NOT the same thing as SFTP (which is part of SSH). FTPS is FTP over SSL (TLS).

I used this to set up the SSL:

I used this to create the certificates I needed:

These were the new/changed files I ended up with:

-rw-r--r-- 1 root root 1124 2009-03-11 13:49 /etc/inetd.conf
-rw-r--r-- 1 root root 1108 2009-03-12 22:30 /etc/proftpd/local.conf
-rw-r--r-- 1 root root  738 2009-03-12 22:24 /etc/proftpd/modules.conf
-rw-r--r-- 1 root root 3808 2009-03-12 22:38 /etc/proftpd/proftpd.conf
-rw-r--r-- 1 root root 2538 2009-03-12 22:30 /etc/proftpd/server.crt
-rw-r--r-- 1 root root  655 2009-03-12 22:30 /etc/proftpd/server.csr
-rw-r--r-- 1 root root  963 2009-03-12 22:30 /etc/proftpd/server.key
-rwxr-xr-x 1 root root 1563 2009-03-11 14:45 /etc/proftpd/sign.sh
-rw-r--r-- 1 root root 2538 2009-03-11 14:50 /etc/ssl/ca.db.certs/01.pem
-rw-r--r-- 1 root root 2538 2009-03-11 14:52 /etc/ssl/ca.db.certs/02.pem
-rw-r--r-- 1 root root 184  2009-03-11 14:52 /etc/ssl/ca.db.index
-rw-r--r-- 1 root root 20   2009-03-11 14:52 /etc/ssl/ca.db.index.attr
-rw-r--r-- 1 root root 92   2009-03-11 14:50 /etc/ssl/ca.db.index.old
-rw-r--r-- 1 root root 3    2009-03-11 14:52 /etc/ssl/ca.db.serial
-rw-r--r-- 1 root root 1155 2009-03-11 14:38 /etc/ssl/certs/ca.crt
-rw-r--r-- 1 root root 951  2009-03-11 14:37 /etc/ssl/private/ca.key

NB: For the purposes of testing I created my own CA with a self-signed certificate to sign the certificates as needed.

I found copies of sign.sh here:

I used the tldp version.

I used this to set up the Chrooted environment:

I added this line:

Include /etc/proftpd/local.conf

to the bottom of /etc/proftpd/proftpd.conf

The local.conf file:

-rw-r--r-- 1 root root 953  2009-03-11 14:57 /etc/proftpd/local.conf


# Chroot everyone to their home directory
DefaultRoot ~
# Configure server for SSL only:
<IfModule mod_tls.c>
    TLSEngine on
    TLSLog /var/log/proftpd/tls.log
    # Support both SSLv3 and TLSv1
    TLSProtocol SSLv3 TLSv1
    # Are clients required to use FTP over TLS when talking to this server?
    # Require SSL/TLS on both channels.
    TLSRequired on
    # Server's certificate
    TLSRSACertificateFile /etc/proftpd/server.crt
    TLSRSACertificateKeyFile /etc/proftpd/server.key
    # CA the server trusts
    TLSCACertificateFile /etc/ssl/certs/ca.crt
    # Authenticate clients that want to use FTP over TLS?
    TLSVerifyClient off
    # Allow SSL/TLS renegotiations when the client requests them, but
    # do not force the renegotations.  Some clients do not support
    # SSL/TLS renegotiations; when mod_tls forces a renegotiation, these
    # clients will close the data connection, or there will be a timeout
    # on an idle data connection.
    TLSRenegotiate required off
    # new
    TLSOptions NoCertRequest
    # TLSTimeoutHandshake 60

In the end it didn't work, and I went to #proftpd on irc.freenode.net where I found castaglia (TJ Saunders) who debugged it with me and got it working.

I found that the version that currently installs on Etch (1.3.0 stable) seems to be configured for the wrong version of SSL.

curl: (35) Unknown SSL protocol error in connection to localhost.localdomain:21

What I did to get it working...

Download the latest source:

$ wget -N ftp://ftp.proftpd.org/distrib/source/proftpd-1.3.2.tar.gz
$ tar xvzf proftpd-1.3.2.tar.gz
$ cd proftpd-1.3.2
$ ./configure --sysconfdir=/etc/proftpd --localstatedir=/var/log --with-modules=mod_tls
$ make

I then had a copy of the latest version of proftpd with TLS support compiled in.

I found some of the 1.3.0 config was incompatible with 1.3.2 (or maybe with the configure options I'd used) so I commented out things to get it working:

These were my changes to /etc/proftpd/proftpd.conf

# diff /etc/proftpd/proftpd.conf.orig /etc/proftpd/proftpd.conf
< Include /etc/proftpd/modules.conf
> # Include /etc/proftpd/modules.conf
< UseIPv6                               on
> UseIPv6                               off
< DisplayFirstChdir               .message
> # DisplayFirstChdir               .message
< <IfModule mod_tls.c>
< TLSEngine off
< </IfModule>
> # <IfModule mod_tls.c>
> # TLSEngine off
> # </IfModule>
> Include /etc/proftpd/local.conf

  • Test it with:

# ./proftpd -nd6

Which gives you lots of debug.

And ended up with:

$ curl --ftp-ssl-reqd --insecure -u <user>:<password> -o i.got.this.file ftp://<server>/dir/test.file

One of the problems that TJ fixed for me was that I'd been trying to run it on port 990.

He got me to change it back to port 21 for Explicit FTPS rather than Implicit FTPS.

(Explicit means you can use either FTP or FTPS on the same port - Implicit tries to hard-wire it to FTPS only on that port, but that's no longer compliant with the RFC.)

Further reading: