FTP

FTP

Install Pure-FTPd
First, install Pure-FTPd using the following command line in Terminal:

sudo apt install pure-ftpd
Basic Configurations
We need to create a new user group named ftpgroup and a new user named ftpuser for FTP users, and make sure this "user" has no login privilege and no home directory:

sudo groupadd ftpgroup
sudo useradd ftpuser -g ftpgroup -s /sbin/nologin -d /dev/null
FTP Home Directory, Virtual User, and User Group
For instance, make a new directory named FTP for the first user:

sudo mkdir /home/$USER/FTP
Make sure the directory is accessible for ftpuser:

sudo chown -R ftpuser:ftpgroup /home/pi/FTP
Create a virtual user named upload, mapping the virtual user to ftpuser and ftpgroup, setting home directory /home/pi/FTP, and record password of the user in database:

sudo pure-pw useradd upload -u ftpuser -g ftpgroup -d /home/pi/FTP -m
A password of that virtual user will be required after this command line is entered. And next, set up a virtual user database by typing:

sudo pure-pw mkdb
Last but not least, define an authentication method by making a link of file /etc/pure-ftpd/conf/PureDB, the number 60 is only for demonstration, make it as small as necessary:

sudo ln -s /etc/pure-ftpd/conf/PureDB /etc/pure-ftpd/auth/60puredb
Restart the program:

sudo service pure-ftpd restart
Test it with an FTP client, like FileZilla.

More Detailed Configurations:
The configuration of Pure-FTPd is simple and intuitive. The administrator only needs to define the necessary settings by making files with option names, like ChrootEveryone, and typing yes, then storing in the directory /etc/pure-ftpd/conf, if all FTP users are to be locked in their FTP home directory (/home/pi/FTP). Here are some recommended settings:

sudo nano /etc/pure-ftpd/conf/ChrootEveryone
Type yes, and press Ctrl + X, Y, and Enter.

Likewise,

Make a file named NoAnonymous and type yes;

Make a file named AnonymousCantUpload and type yes;

Make a file named AnonymousCanCreateDirs and type no;

Make a file named DisplayDotFiles and type no;

Make a file named DontResolve and type yes;

Make a file named ProhibitDotFilesRead and type yes;

Make a file named ProhibitDotFilesWrite and type yes;

Make a file named FSCharset and typeUTF-8;

...

Restart pure-ftpd again and apply the above settings.

sudo service pure-ftpd restart