FTP-сервером я выбрал proftpd, потому что pure-ftp мне для моих нужд не нужен и этот вышел первый в поиске. В рунете куча мануалов, но мне толком ни один не помог.Установка, как обычно, не таит в себе никакого подвоха:

sudo  aptitude install proftpd

В процессе установки он спросит, как будем запускать сервер — через initd или standalone, я выбрал второй вариант, ибо мне так удобнее. Отличия в вариантах описаны в том же диалоге, так что каждый может выбрать вариант, удобный для себя.

Далее нужно изобразить шелл для пользователя FTP:

sudo nano /etc/shells

там в конце добавим строчку

/bin/false

Теперь создадим папку для файлов:

sudo mkdir /home/FTPsess

и в ней папки:

sudo mkdir /home/FTPsess/upload
sudo mkdir /home/FTPsess/public

и раздадим права на запись в эти папки:

sudo chmod 755 /home/FTPsess
sudo chmod 755 /home/FTPsess/public
sudo chmod 777 /home/FTPsess/upload

Для того, чтобы proftpd мог работать с этими папками, создадим пользователя:

sudo useradd userftp -p MYPASSWORD -d /home/FTPsess -s /bin/false

Соответственно, вместо MYPASWORD пишем свой пароль для этого пользователя.

Делаем себе копию конфига, с которой будем работать, чтобы не поломать оригинальный конфиг:

sudo cp /etc/proftpd/proftpd.conf /etc/proftpd/proftpd.conf.sample

ну и правим его:

sudo nano /etc/proftpd/proftpd.conf

А вот тут случилась засада. Прилагаю свой конфиг:

#
# /etc/proftpd/proftpd.conf -- This is a basic ProFTPD configuration file.
# To really apply changes, reload proftpd after modifications, if
# it runs in daemon mode. It is not required in inetd/xinetd mode.
#

# Includes DSO modules
Include /etc/proftpd/modules.conf

# Set off to disable IPv6 support which is annoying on IPv4 only boxes.
UseIPv6 off
# If set on you can experience a longer connection delay in many cases.
IdentLookups off

ServerName "Debian"
ServerType standalone
DeferWelcome off

MultilineRFC2228 on
DefaultServer on
ShowSymlinks on

TimeoutNoTransfer 600
TimeoutStalled 600
TimeoutIdle 1200

DisplayLogin welcome.msg
DisplayChdir .message true
ListOptions "-l"

DenyFilter \*.*/

# делаем /home/FTP директорию домашней
DefaultRoot /home/FTPsess

# вводим запрет на выход пользователей за пределы своей домашней директории
DefaultRoot ~

# Users require a valid shell listed in /etc/shells to login.
# Use this directive to release that constrain.
# RequireValidShell off

# Port 21 is the standard FTP port.
Port 21

# In some cases you have to specify passive ports range to by-pass
# firewall limitations. Ephemeral ports can be used for that, but
# feel free to use a more narrow range.
# PassivePorts 49152 65534

# If your host was NATted, this option is useful in order to
# allow passive tranfers to work. You have to use your public
# address and opening the passive ports used on your firewall as well.
# MasqueradeAddress 1.2.3.4

# This is useful for masquerading address with dynamic IPs:
# refresh any configured MasqueradeAddress directives every 8 hours
<IfModule mod_dynmasq.c>
# DynMasqRefresh 28800
</IfModule>

# 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

# Set the user and group that the server normally runs at.
User proftpd
Group nogroup

# Umask 022 is a good standard umask to prevent new files and dirs
# (second parm) from being group and world writable.
Umask 022 022
# Normally, we want files to be overwriteable.
AllowOverwrite on

# Uncomment this if you are using NIS or LDAP via NSS to retrieve passwords:
# PersistentPasswd off

# This is required to use both PAM-based authentication and local passwords
# AuthOrder mod_auth_pam.c* mod_auth_unix.c

# Be warned: use of this directive impacts CPU average load!
# Uncomment this if you like to see progress and transfer rate with ftpwho
# in downloads. That is not needed for uploads rates.
#
# UseSendFile off

TransferLog /var/log/proftpd/xferlog
SystemLog /var/log/proftpd/proftpd.log

# In order to keep log file dates consistent after chroot, use timezone info
# from /etc/localtime. If this is not set, and proftpd is configured to
# chroot (e.g. DefaultRoot or <Anonymous>), it will use the non-daylight
# savings timezone regardless of whether DST is in effect.
#SetEnv TZ :/etc/localtime

<IfModule mod_quotatab.c>
QuotaEngine off
</IfModule>

<IfModule mod_ratio.c>
Ratios off
</IfModule>

# Delay engine reduces impact of the so-called Timing Attack described in
# http://security.lss.hr/index.php?page=details&ID=LSS-2004-10-02
# It is on by default.
<IfModule mod_delay.c>
DelayEngine on
</IfModule>

<IfModule mod_ctrls.c>
ControlsEngine off
ControlsMaxClients 2
ControlsLog /var/log/proftpd/controls.log
ControlsInterval 5
ControlsSocket /var/run/proftpd/proftpd.sock
</IfModule>

<IfModule mod_ctrls_admin.c>
AdminControlsEngine off
</IfModule>

#
# Alternative authentication frameworks
#
#Include /etc/proftpd/ldap.conf
#Include /etc/proftpd/sql.conf

#
# This is used for FTPS connections
#
#Include /etc/proftpd/tls.conf

#
# Useful to keep VirtualHost/VirtualRoot directives separated
#
#Include /etc/proftpd/virtuals.con

# Этой опцией задается alias пользователю (в моем примере это userftpalias)
UserAlias userftpalias userftp

# A basic anonymous configuration, no upload directories.

# <Anonymous ~ftp>
# User ftp
# Group nogroup
# # We want clients to be able to login with "anonymous" as well as "ftp"
# UserAlias anonymous ftp
# # Cosmetic changes, all files belongs to ftp user
# DirFakeUser on ftp
# DirFakeGroup on ftp
#
# RequireValidShell off
#
# # Limit the maximum number of anonymous logins
# MaxClients 10
#
# # We want 'welcome.msg' displayed at login, and '.message' displayed
# # in each newly chdired directory.
# DisplayLogin welcome.msg
# DisplayChdir .message
#
# # Limit WRITE everywhere in the anonymous chroot
# <Directory *>
# <Limit WRITE>
# DenyAll
# </Limit>
# </Directory>
#
# # Uncomment this if you're brave.
# # <Directory incoming>
# # # Umask 022 is a good standard umask to prevent new files and dirs
# # # (second parm) from being group and world writable.
# # Umask 022 022
# # <Limit READ WRITE>
# # DenyAll
# # </Limit>
# # <Limit STOR>
# # AllowAll
# # </Limit>
# # </Directory>
#
# </Anonymous>

# Include other custom configuration files

После этого всего, я смог зайти на мой FTP с логином и паролем моего пользователя Ubuntu.