Want to set up an SFTP server on Ubuntu? Configuring the SFTP protocol allows for a more secure transfer of files between the SFTP host and client machines. Unfortunately, as you may already know, FTP is inherently insecure, so most implementations are SFTP.
An even more secure implementation will be to enable chroot. A chroot isolates applications from the rest of your computer by putting them in jail.
When you enable chroot on a user account, that account is isolated and can only access its directory and files and nowhere else.
This brief tutorial will show students and new users how to set up sFTP on Ubuntu 16.04 / 17.10 and 18.04 with chroot enabled on Ubuntu home directories.
To get started, continue with the steps below
Install Open SSH Server
If you haven’t installed the Open SSH server, run the commands below to install it.
sudo apt update sudo apt install openssh-server
After installing, the commands below can stop, start, and enable the service to start when the server boots.
sudo systemctl stop ssh.service sudo systemctl start ssh.service sudo systemctl enable ssh.service
Now that OpenSSH Server is installed, open its default configuration file by running the commands below.
sudo nano /etc/ssh/sshd_config
Then edit the file and change highlighted line below. Add the # before the first line, then add the highlighted line below to enable SFTP. This will change the subsystem to internal-sftp only.
# override default of no subsystems #Subsystem sftp /usr/lib/openssh/sftp-server Subsystem sftp internal-sftp
Next, add the lines below at the end of the file or just below the highlighted line above.
# Example of overriding settings on a per-user basis #Match User anoncvs # X11Forwarding no # AllowTcpForwarding no # PermitTTY no # ForceCommand cvs server Match Group sftp_users X11Forwarding no AllowTcpForwarding no ChrootDirectory /home ForceCommand internal-sftp
Save the file and exit.
After editing the file, run the commands below to restart OpenSSH Server.
sudo systemctl restart ssh.service
Create SFTP Group
Now that you have defined your SFTP settings and set them to match the sftp_users. Create a sftp_users group, then add users you want to restrict via chroot. To create the group, run the commands below.
sudo groupadd sftp_users
Now add any user to the group by running the commands below.
sudo usermod -aG sftp_users richard
Replace user richard with your Ubuntu account name. This will add the user to the sftp_users group you created above.
That’s it! Your system should be configured for secure SFTP for your users.
Users can securely use their favorite FTP client Filezilla to connect to the server via SFTP protocol. Users will be restricted to their directories and nowhere else.
Make sure to select SFTP connection in Filezilla.
When you connect, you’ll be prompted to accept the server key. Accept it and continue.
Connect and use the SFTP service.