Proftpd - SFTP with Virtual Users

Question

I'm trying to configure a SFTP with Proftpd. I've successfully configured the SFTP with Unix Users, but now I'd like to use virtual users, as I'll have an important amount of users to add/delete. I want the users to login with username/password.

For this, I've first followed the tutorial Using SFTP with ProFTPd then tried others.

Here is the configuration for the SFTP server :

Include /etc/proftpd/modules.conf


ServerName                      "Nom du FTP"
ServerType                      standalone
DefaultServer                   on

# Umask 022 is a good standard umask to prevent new dirs and files
# from being group and world writable.
Umask                           022

# To prevent DoS attacks, set the maximum number of child processes
# to 30.  If you need to allow more than 30 concurrent connections
# at once, simply increase this value.  Note that this ONLY works
# in standalone mode, in inetd mode you should use an inetd server
# that allows you to limit maximum number of processes per service
# (such as xinetd).
MaxInstances                    30

RequireValidShell               off

# Set the user and group under which the server will run.
User                            proftpd
Group                           nogroup

SFTPEngine         on

Port               2222
SFTPLog            /var/log/proftpd/sftp.log
TransferLog        /var/log/proftpd/sftp-xferlog

# Host Keys
SFTPHostKey        /etc/ssh/ssh_host_rsa_key
SFTPHostKey        /etc/ssh/ssh_host_dsa_key

# Auth methods
SFTPAuthMethods    password
AuthUserFile       /etc/proftpd/sftp.passwd
AuthGroupFile      /etc/proftpd/sftp.group

# SFTP specific configuration
DefaultRoot        ~

# Normally, we want files to be overwriteable.
<Directory />
  AllowOverwrite                on
</Directory>

I've generated the passwords using the command ftpasswd --hash.

But, when I try to connect using FileZilla, I've got the message :

Authentification failed
Critical error
Can't establish a connection to the server

When I look into the logs of proftpd :

2014-09-08 15:13:53,636 mod_sftp/0.9.9[6343]: error using DisplayLogin 'welcome.msg': No such file or directory

2014-09-08 15:13:53,637 mod_sftp/0.9.9[6343]: sent server version 'SSH-2.0-mod_sftp/0.9.9'

2014-09-08 15:13:53,704 mod_sftp/0.9.9[6343]: received client version 'SSH-2.0-PuTTY_Local:_Jun__1_2014_11:08:49'

2014-09-08 15:13:53,704 mod_sftp/0.9.9[6343]: handling connection from SSH2 client 'PuTTY_Local:_Jun__1_2014_11:08$

2014-09-08 15:13:53,711 mod_sftp/0.9.9[6343]:  + Session key exchange: diffie-hellman-group-exchange-sha256

2014-09-08 15:13:53,711 mod_sftp/0.9.9[6343]:  + Session server hostkey: ssh-rsa

2014-09-08 15:13:53,711 mod_sftp/0.9.9[6343]:  + Session client-to-server encryption: aes256-ctr

2014-09-08 15:13:53,711 mod_sftp/0.9.9[6343]:  + Session server-to-client encryption: aes256-ctr

2014-09-08 15:13:53,711 mod_sftp/0.9.9[6343]:  + Session client-to-server MAC: hmac-sha2-256

2014-09-08 15:13:53,711 mod_sftp/0.9.9[6343]:  + Session server-to-client MAC: hmac-sha2-256

2014-09-08 15:13:53,711 mod_sftp/0.9.9[6343]:  + Session client-to-server compression: none

2014-09-08 15:13:53,711 mod_sftp/0.9.9[6343]:  + Session server-to-client compression: none

2014-09-08 15:13:54,142 mod_sftp/0.9.9[6343]: sending acceptable userauth methods: password

2014-09-08 15:13:56,764 mod_sftp/0.9.9[6343]: sending userauth failure; remaining userauth methods: password

2014-09-08 15:13:56,764 mod_sftp/0.9.9[6343]: client sent SSH_MSG_IGNORE message (160 bytes)

2014-09-08 15:13:56,832 mod_sftp/0.9.9[6343]: error reading from client (fd 0): Connection reset by peer

2014-09-08 15:13:56,832 mod_sftp/0.9.9[6343]: disconnecting client (Connection reset by peer)

I don't understand why it doesn't work. If I simply delete the lines :

AuthUserFile       /etc/proftpd/sftp.passwd
AuthGroupFile      /etc/proftpd/sftp.group

The connection works perfectly with the Unix users. Have I forgotten anything ?

I'm using Ubuntu server 14.04.

Answer 1

What happens if you use the following in your proftpd.conf:

# Tell proftpd to only use the AuthUserFile/AuthGroupFile
AuthOrder mod_auth_file.c

and, in addition, remove this from your proftpd.conf:

SFTPAuthMethods password

The mod_sftp module automatically discovers what auth methods it can provide to clients. Specifically, the 'keyboard-interactive' auth method is often something that clients want to use over 'password', and 'keyboard-interactive' can also use the AuthUserFile you have configured.

Hope this helps!