ubuntu ftp server

Reference link: <http://www.krizna.com/ubuntu/setup-ftp-server-on-ubuntu-14-04-vsftpd/>

FTP is used to transfer files from one host to another over a TCP network. This article explains how to set up an FTP server on Ubuntu 14.04.

There are three popular FTP server packages: Pure-FTPd, vsftpd, and ProFTPD. This guide uses vsftpd, which is lightweight and has a smaller attack surface.

Setup FTP server on Ubuntu 14.04

Step 1: Update repositories.

sudo apt-get update

Step 2: Install the vsftpd package.

sudo apt-get install vsftpd

Step 3: Open /etc/vsftpd.conf and make the following changes.

Uncomment these lines:

write_enable=YES
local_umask=022

Uncomment this line to prevent users from accessing folders outside their home directories:

chroot_local_user=YES

Add the following line at the end of the file:

allow_writeable_chroot=YES

Add these lines to enable passive mode:

pasv_enable=Yes
pasv_min_port=40000
pasv_max_port=40100

Step 4: Restart the vsftpd service.

sudo service vsftpd restart

Step 5: The FTP server will now listen on port 21. Create a user with the following commands. Use the /usr/sbin/nologin shell to prevent FTP users from accessing a normal shell session.

sudo useradd -m john -s /usr/sbin/nologin
sudo passwd john

Step 6: Allow login access for the nologin shell. Open /etc/shells and add this line at the end:

/usr/sbin/nologin

Now try to connect to the FTP server with this username on port 21 using WinSCP or the FileZilla client. Confirm that the user cannot access folders outside the home directory.

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Using plain FTP on port 21 is a significant security risk. It is highly recommended to use SFTP instead. Continue below for SFTP configuration.

Secure FTP (SFTP)

SFTP is commonly called “Secure FTP” and uses the SSH File Transfer Protocol. It requires the openssh-server package. Install it if it is not already installed:

sudo apt-get install openssh-server

Step 7: Create a new group named ftpaccess for FTP users.

sudo groupadd ftpaccess

Step 8: Edit /etc/ssh/sshd_config.

Find and comment out this line:

Subsystem sftp /usr/lib/openssh/sftp-server

Add these lines at the end of the file:

Subsystem sftp internal-sftp
Match group ftpaccess
ChrootDirectory %h
X11Forwarding no
AllowTcpForwarding no
ForceCommand internal-sftp

Step 9: Restart the SSH service.

sudo service ssh restart

Step 10: Follow these steps when creating users for SFTP access.

Create the user john with the ftpaccess group and the /usr/sbin/nologin shell:

sudo useradd -m john -g ftpaccess -s /usr/sbin/nologin
sudo passwd john

Change ownership of the home directory:

sudo chown root /home/john

Create a writable folder inside the home directory and change ownership of that folder:

sudo mkdir /home/john/www
sudo chown john:ftpaccess /home/john/www

Now try to connect to the server using SFTP on port 22. Confirm that users can upload files to the www directory and cannot access folders outside the home directory.

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If you want to use both FTP and SFTP together, follow Step 10 when creating users. For existing users, move them to the ftpaccess group and create the folder structure with the correct ownership:

sudo usermod john -g ftpaccess -s /usr/sbin/nologin
sudo chown root /home/john
sudo mkdir /home/john/www
sudo chown john:ftpaccess /home/john/www

Now john can upload files to the www folder using both FTP and SFTP.