Raspberry Pi: Set up an FTP server under Debian with ProFTPd

Raspberry Pi: Set up an FTP server under Debian with ProFTPd

In the following tutorial we will install an FTP server on the Raspberry Pi and set up a user for it. My tutorial actually works, unlike other tutorials, because my tutorials are live tested and not just blindly written.

Part 1: Install and set up FTP server

First we install ProFTPd as FTP server

apt-get install proftpd

After that we get an ID which we remember for later on

id www-data

We open the configuration

nano /etc/proftpd/proftpd.conf

and extend it at the end with the following code:

DefaultRoot ~
AuthOrder mod_auth_file.c mod_auth_unix.c
AuthUserFile /etc/proftpd/ftpd.passwd
AuthPAM off
RequireValidShell off

We save the file with Ctrl + X and create a directory

mkdir /home/ftpuser
chmod 775 /home/ftpuser
chown -R www-data:www-data /home/ftpuser

and change to the ProFTPd directory

cd /etc/proftpd/

In the following command the ID determined above will be required again, here in the example as ID 33

ftpasswd --passwd --name ftpuser --uid 33 --gid 33 --home /home/ftpuser --shell /bin/false

Important: If the hostname is not set, an error will occur, therefore we set a hostname

Tip: To delete just add “–delete-user” in front.

hostnamectl set-hostname debian

Now we restart the FTPd server

/etc/init.d/proftpd restart

Part 2: Raspberry Pi FTP server with USB hard drive

You want to set up a Raspberry Pi FTP server with a USB hard disk? Then the following part of my tutorial might help you. First you have to connect the USB harddisk, then you can set the name of the harddisk with

fdisk -l

can be read out. In our example the USB hard disk is /dev/sda1. In the following example we create a new partition table with fdisk on the harddisk

fdisk /dev/sda1
g
n
1
ENTER
ENTER
w

and submit the changes to the kernel

partx /dev/sda1

then we can create a file system

mke2fs -j /dev/sda1

We now mount the disk to the path of the previously created directory

mount -v -o rw /dev/sda1 /home/ftpuser

To be on the safe side we set the appropriate file permissions again

chmod 775 /home/ftpuser
chown -R www-data:www-data /home/ftpuser

And extend the boot table with

nano /etc/fstab/

with the following content

/dev/sda1 /home/ftpuser auto rw 0 0

Finally we restart the FTPd

/etc/init.d/proftpd restart

Part 3: Own service for autostart or automount

An alternative to the boot table would be an own service as shellscript. The advantage of this is that the boot process is not interrupted unnecessarily in case of errors.

For this we change into the Systemd directory:

cd /etc/systemd/system

and create a new simple service with nano

nano automountusb.service

Here we enter all details of our shellscript

[Unit]
Description=Automount USB by lautenbacher.ch

[Service]
Type=simple
ExecStart=/bin/bash /home/automount.sh

[Install]
WantedBy=multi-user.target

Then we generate our shell script with nano

nano /home/automount.sh

and the following content

mount -v -o rw /dev/sda1 /home/ftpuser
chmod 775 /home/ftpuser
chown -R www-data:www-data /home/ftpuser

We make the shell script executable

chmod 777 /home/automount.sh

and enable the newly created service

systemctl enable automountusb.service

After a reboot with

reboot

the output per

df

should show that /dev/sda1/ is mounted to the path /home/ftpuser/:

Automounted USB on Raspberry PI

Part 4: TLS/SSL Encryption

First, two new packages need to be installed

apt-get install ssl-cert
apt-get install proftpd-mod-crypto

After that we generate the certificate:

make-ssl-cert generate-default-snakeoil -force-overwrite

and change the modules.conf by removing the comment (#) from the “mod_tls” module

nano /etc/proftpd/modules.conf

then we create a custom configuration

nano /etc/proftpd/conf.d/proftp-custom.conf

under store the following content:


    RequireValidShell off

# Default directory is ftpusers home
DefaultRoot ~ ftpuser
# Limit login to the ftpuser group

    DenyGroup !ftpuser



        TLSEngine on
        TLSLog /var/log/proftpd/tls.log
        TLSProtocol TLSv1
        TLSRSACertificateFile /etc/ssl/certs/ssl-cert-snakeoil.pem
        TLSRSACertificateKeyFile /etc/ssl/private/ssl-cert-snakeoil.key
        TLSVerifyClient off
        TLSRequired on
TLSOptions NoSessionReuseRequired

After that we change to the ProFTPd directory

cd /etc/proftpd

and create a new system user (note that this differs from the above)

adduser ftpuser -shell /bin/false -home /home/ftpuser

Since the uid and gid changed by creating a system user we have to assume corresponding adjustments here as well, so we change the password configuration of ProFTPd as well (again):

ftpasswd --passwd --name ftpuser --uid 1000 --gid 1000 --home /home/ftpuser --shell /bin/false

Of course, the owner must then be changed as well

chown ftpuser:ftpuser /home/ftpuser

and then restart the service

/etc/init.d/proftpd restart

If you have set up the automount service above you have to change the shellscript accordingly (remove “-R” for part 5)

nano /home/automount.sh

Part 5: Create subaccounts

The code below should speak for itself, the only important thing here is that the new user is assigned to the group ftpuser.

cd /etc/proftpd
mkdir /home/ftpuser/ftpusera
adduser ftpusera -shell /bin/false -home /home/ftpuser/ftpusera
ftpasswd --passwd --name ftpusera --uid 1001 --gid 1000 --home /home/ftpuser/ftpusera --shell /bin/false
chown -R ftpusera:ftpuser /home/ftpuser/ftpusera
usermod -a -G ftpuser ftpusera
/etc/init.d/proftpd restart

Part 6: Other settings / Passive ports

In order to make the FTP(S) server reachable from the outside, some settings regarding the passive ports and IP have to be made. Otherwise we get e.g. the error message “unroutable address” or the directory content can not be read.

First we create a new configuration file

nano /etc/proftpd/passive.conf

with the following content:


PassivePorts 49152 65535

We then execute the following commands

/sbin/modprobe nf_conntrack_ftp
/sbin/modprobe nf_nat_ftp
echo nf_nat_ftp >> /etc/modules-load.d/modules.conf
echo nf_conntrack_ftp >> /etc/modules-load.d/modules.conf

To be on the safe side we also change the original configuration file again

nano /etc/proftpd/proftpd.conf

Here we enter the public IP address as DefaultAddress and – often forgotten – as Masquerade Address. Additionally we enter the passive ports here.

DefaultAddress 1.1.1.1
MasqueradeAddress 1.1.1.1
PassivePorts 49152 65535

After that we restart the service and can check the NAT settings with the last command.

service proftpd restart
lsmod | grep nf_nat_ftp

After these settings the FTPS server is reachable cleanly even behind an iptables firewall.

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