Install and Configure PureFTPd Ubuntu 18.04

Install the PureFTPd :

sudo apt-get install pure-ftpd -y

Edit /etc/inetd.conf file and comment out (add a # at the start of) the line containing ftp if such an entry exists:

sudo vi /etc/inetd.conf

Edit /etc/default/pure-ftpd-common and verify the STANDALONE_OR_INETD=standalone entry is set:

sudo vi /etc/default/pure-ftpd-common

Add a "ftpgroup" in the system:

sudo groupadd ftpgroup

Add a "ftpuser" user in the system:

sudo useradd -g ftpgroup -d /dev/null -s /etc ftpuser

Add a virtual pure-ftpd user. I'm going to use "joe" as an example:

sudo pure-pw useradd joe -u ftpuser -d /name/of/directory

where /name/of/directory is the directory where you want user joe to have FTP access. This directory is where user joe is going to be locked in once they log on the server with FTP. Whether you create a directory for joe to have access or you use an existing directory, ensure the user/group ftpuser/ftpgroup you created earlier is the owner of that directory as follows:

chown -R ftpuser:ftpgroup /name/of/directory

Now, create the PureFTPd virtual user database:

sudo pure-pw mkdb

Create the following symbolic links for Pure-FTPD to funtion properly:

sudo ln -s /etc/pure-ftpd/pureftpd.passwd /etc/pureftpd.passwd
sudo ln -s /etc/pure-ftpd/pureftpd.pdb /etc/pureftpd.pdb
sudo ln -s /etc/pure-ftpd/conf/PureDB /etc/pure-ftpd/auth/PureDB

Ensure that the file /etc/pure-ftpd/conf/UnixAuthentication file only contains the word no:

sudo vi /etc/pure-ftpd/conf/UnixAuthentication

Restart PureFTPd before changes take effect:

sudo /etc/init.d/pure-ftpd restart

Configure PureFTPd Options

PureFTPd on Ubuntu/Debian distros use the pure-ftpd-wrapper which will parse any properly named file in the "/etc/pure-ftpd/conf" directory and read the values and in turn pass to the pure-ftpd daemon. This eliminates the need editing long configuration files. There are a lot of files that can be placed in the "/etc/pure-ftpd/conf" directory for different configuration options, but I'm only going to concentrate on a handful. For a complete list of all the files refer to the following http://manpages.ubuntu.com/manpages/har ... per.8.html link.

Passive Mode Port Range

Passive mode can be enabled by simply issuing the following from the command line for setting a range of 30000 through 31000:

echo  30000 31000 > /etc/pure-ftpd/conf/PassivePortRange

Bind pure-ftpd daemon to specific address and port number

If you wish to set pure-ftpd to listen to a specific port number, issue the following from the command line. In this example we set port number "666" as the FTP port:

echo 192.168.xxx.xxx,666 > /etc/pure-ftpd/conf/Bind

Disable name resolution in PureFTPd

echo 'yes' > /etc/pure-ftpd/conf/DontResolve

Set passive IP in PureFTPd

If you are behind a NAT, it’s recommended you set the public IP address of your Pure-ftpd server as follows:

echo '1.2.3.4' > /etc/pure-ftpd/conf/ForcePassiveIP

Enable TLS on PureFTPd

The FTP protocol in general is very insecure. The username/passwords are sent using clear text and the data transfers are also insecure. Enabling TLS will allow you to secure your FTP sessions to include the username/passwords as well as the data transfers.

Install OpenSSL:

sudo apt-get install openssl -y

If you want to accept plain AND TLS sessions, issue the following on the command line:

echo 1 > /etc/pure-ftpd/conf/TLS

If you want to accept TLS sessions ONLY, issue the following on the command line:

echo 2 > /etc/pure-ftpd/conf/TLS

Create the SSL certificate for TLS

Create a "private" directory under "/etc/ssl/" if one doesn't exist yet:

mkdir /etc/ssl/private

Generate a self-signed certificate as follows:

openssl req -x509 -nodes -days 7300 -newkey rsa:2048 -keyout /etc/ssl/private/pure-ftpd.pem -out /etc/ssl/private/pure-ftpd.pem

Fill in the certificate information as required.

For 3rd party SSL certificates, enter the private key and corresponding chain certs in the following order inside /etc/ssl/private/pure-ftpd.pem:

-----BEGIN RSA PRIVATE KEY-----

(Private Key)

-----END RSA PRIVATE KEY-----

-----BEGIN CERTIFICATE-----

(Primary SSL certificate)

-----END CERTIFICATE-----

-----BEGIN CERTIFICATE-----

(Intermediate certificate)

-----END CERTIFICATE-----

-----BEGIN CERTIFICATE-----

(Root certificate)

-----END CERTIFICATE-----

Troubleshooting

You may see the following warning when trying to connect to your PureFTPd server:

[WARNING] Can't login as [joe]: account disabled
"Sorry, but I can't trust you" 
[WARNING] Can't login as [joe]: account disabled (uid < 1021)

These two warnings occur if your system set the UserID (UID) and/or GroupID (GID) associated with the ftpuser user are below 1000. To see what the current values are, type the following at a shell:

id ftpuser

Should output similar to below:

uid=572(ftpuser) gid=972(ftpgroup) groups=972(ftpgroup)

The actual numbers don't matter much, but they should be equal or higher than 1000 for Pure-FTPD to be happy. To fix the UserID (UID) portion, open a shell and type:

sudo usermod -u 1021 -p -U ftpuser

To fix the GroupID (GID):

sudo groupmod -g 1021 ftpgroup

Additionally, you can set the MinUID that PureFTPd expects by setting the following:

echo  1021 > /etc/pure-ftpd/conf/MinUID

Ensure to restart the Pure-FTPD daemon:

systemctl restart pure-ftpd

Manage PureFTPd Users

The commands below are for performing common tasks with the pure-ftpd user database. This assumes that "username" is the user you are managing and "/name/of/directory" is the directory you want that user to have FTP access. Remember that after every change in the pure-ftpd database, you MUST commit the changes by typing "sudo pure-pw mkdb" and always make sure that "ftpuser/ftpgroup" are the owners of whatever directory you want that user to have access:

Add Users:

sudo pure-pw useradd username -u ftpuser -d /name/of/directory

Change User Password:

sudo pure-pw passwd username

Show User Details:

sudo pure-pw show username

Delete user:

sudo pure-pw userdel username

Update PureFTPd Virtual User Database:

sudo pure-pw mkdb