Proftpd is one of the most popular FTP servers for Linux. Easy to configure - it's usable right after installation.
WARNING:After installing proftpd we get full access to files and directories on the server!!! That's why I would advise against leaving proftpd in its default configuration.
Before discussing the basic configuration, we need to ask ourselves: "who should our file server serve, and what resources should it expose?"
We have a choice of:

• system users - users who have shell account access on our server (trusted)
• ftp users - users who only have access to an FTP account (less trusted)
• anonymous users - users with access to so-called anonymous FTP, i.e. usually able to download files made available by the administrator without providing a login or password

# Include the configs of any activated modules.
Include /etc/proftpd/modules.conf

# Server operating mode, run as a standalone process.
ServerType                      standalone
# Set this configuration as the default one
DefaultServer                   on

# If we don't use IPv6.
UseIPv6                         off

# These 3 options significantly shorten login time.
UseReverseDNS                   off
IdentLookups                    off
ServerIdent                     off

# We set our server name; we don't give its name or version.
ServerName                      "ftp by ulos.pl"

# Welcome message.
DisplayLogin                    welcome.msg

# We allow the welcome message only after logging in.
DeferWelcome                    on

MultilineRFC2228                on

# We allow displaying symlinks.
ShowSymlinks                    on

# Time after which the connection to the server will be terminated.
TimeoutNoTransfer               600
TimeoutStalled                  600
TimeoutIdle                     1200


DisplayChdir                    .message true

DenyFilter                      \*.*/

# Block root login.
RootLogin                       off

# Trap the user in a designated directory they can't escape from.
# the ~ sign is the home directory on Linux.
DefaultRoot                     ~

# Options for listing files in binary mode:
# "-a"="ls -a" , "+a"=block the a parameter, i.e. hidden files (starting with a dot).
ListOptions "+a"

# We check whether the user logging in
# has a shell assigned in /etc/shells (a quick way to block them).
RequireValidShell               on

# The port on which proftpd listens.
Port                            21

# Passive mode port configuration used by browsers (ftp://host.pl).
# PassivePorts                  49152 65534

# A useful option if our computer is behind NAT.
# MasqueradeAddress             1.2.3.4

# This is useful for masquerading address with dynamic IPs:
# refresh any configured MasqueradeAddress directives every 8 hours

# DynMasqRefresh 28800


# Maximum number of FTP daemon processes. 
# Thanks to this directive we can protect ourselves against DoS-type attacks. 
MaxInstances                    30

# The user and group the server process will belong to.
User                            proftpd
Group                           nogroup

# Setting owner access rights for modifying files and directories.
# 022 => 755 , 077 => 700 , 002 =>  775
Umask                           022  022

# Allow overwriting files.
AllowOverwrite                  on

# Log configuration.
TransferLog /var/log/proftpd/xferlog
SystemLog   /var/log/proftpd/proftpd.log

This is an example of a basic proftpd configuration while maintaining certain security standards for system users.
It's worth mentioning one more important thing: the FTP protocol sends passwords and logins in unencrypted form , i.e. as so-called plain text, which makes it possible to eavesdrop on this fairly important information.

Now we'll deal with virtual users, who will only have an FTP account.

• The first step will be to create a directory for virtual users and give it the appropriate permissions.
mkdir /home/ftp
chown proftpd:nobody /home/ftp
chmod 751 /home/ftp
• We create users using the ftpasswd tool:

ftpasswd --passwd --file /etc/proftpd/ftpd.passwd --name username  --home /home/ftp/directory_name -p  --uid ftp_user_id  --gid ftp_group_id --shell /bin/false


where: ftp_user_id and ftp_group_id come from the proftpd.conf directives: User and Group
We can use a simple script that will save us from tediously typing so many parameters:

• mcedit ftpcreate.sh

#!/bin/sh
if [ $# -lt 2 ] ; then
echo "pass the username as the first parameter, and their folder as the second parameter"
else
ftpasswd --passwd --file /etc/proftpd/.ftpd.passwd --name $1  --home /home/ftp/$2 -p  --uid 106  --gid 65534 --shell /bin/false
mkdir -p /home/ftp/$2
chown -R proftpd:nogroup /home/ftp/$2
chmod 751 /home/ftp/$2
fi


We set the appropriate permissions: chmod 700 ftpcreate.sh We use it as follows: ./ftpcreate.sh username their_folder, after which it will ask for a password...
Let's also remember to modify the permissions of the ftpd.passwd file: chmod 600 .ftpd.passwd
• Next, we need to slightly modify the main configuration file proftpd.conf
We add the path to the file with users and passwords, in our case: AuthUserFile /etc/proftpd/ftpd.passwd
We change the directive: RequireValidShell on to RequireValidShell off

At this point, the server handles both virtual and system users.