VsFTPD ” Very Secure FTP Daemon”
VsFTPD “very secure FTP daemon” is an open source FTP server for Linux systems, in this quick guide we will install VsFTPD on a Ubuntu server and secure the FTP server with SSL/TLS. Please visit the official website of VsFTPD if you need more information about the application.
Requirements
- Ubuntu Server 18.04
- User with sudo privileges.
- Static IP address
- Configured firewall
- Server connected to internet
For more information on how to create a sudo and configure a static IP please see the quick guides Create Sudo User , Set Static IP address and Configure Ubuntu Firewall.
Install VsFTPD
Vsftpd is available in Ubuntu 18.04 default repository and do not require any extra pre configuration. to start installing Vsftpd run the following command.
sudo apt-get install vsftpd -y
Wait for the application to finish installing, once it is installed start the Vsftpd service and enable it to start on boot.
sudo systemctl start vsftpd sudo systemctl enable vsftpd
Verify that the VsFTPD is up and running.
sudo systemctl status vsftpd
root@iphone:~# sudo systemctl status vsftpd
● vsftpd.service - vsftpd FTP server
Loaded: loaded (/lib/systemd/system/vsftpd.service; enabled; vendor preset: enabled)
Active: active (running) since Sat 2019-06-08 18:17:39 UTC; 2min 54s ago
Main PID: 2311 (vsftpd)
Tasks: 1 (limit: 2214)
CGroup: /system.slice/vsftpd.service
Jun 08 18:17:39 iphone systemd[1]: Starting vsftpd FTP server...
Jun 08 18:17:39 iphone systemd[1]: Started vsftpd FTP server.
Configure The Firewall
We need to open port 20 and 21 for active FTP and ports 40000-50000 for passive FTP.
sudo ufw allow 20/tcp
sudo ufw allow 21/tcp
sudo ufw allow 40000:50000/tcp
Display the firewall rules.
sudo ufw status
root@iphone:~# sudo ufw status Status: active To Action From -- ------ ---- 22/tcp ALLOW Anywhere OpenSSH ALLOW Anywhere 21/tcp ALLOW Anywhere 40000:50000/tcp ALLOW Anywhere 22/tcp (v6) ALLOW Anywhere (v6) OpenSSH (v6) ALLOW Anywhere (v6) 21/tcp (v6) ALLOW Anywhere (v6) 40000:50000/tcp (v6) ALLOW Anywhere (v6) root@iphone:~#
Create FTP User
Create a low privileges user that can be used to access the FTP server. When prompted enter password and user information for the user.
sudo adduser ftpuser
root@iphone:~# sudo adduser ftpuser
Adding user `ftpuser' ...
Adding new group `ftpuser' (1001) ...
Adding new user `ftpuser' (1001) with group `ftpuser' ...
Creating home directory `/home/ftpuser' ...
Copying files from `/etc/skel' ...
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully
Changing the user information for ftpuser
Enter the new value, or press ENTER for the default
Full Name []:
Room Number []:
Work Phone []:
Home Phone []:
Other []:
Is the information correct? [Y/n] y
root@iphone:~#
Create a FTP Directory For The FTP User
First we want to create a FTP folder for the ftpuser.
sudo mkdir /home/ftpuser/ftp
Next we want to set the folder ownership.
sudo chown nobody:nogroup /home/ftpuser/ftp
Remove write permissions to the ftp folder.
sudo chmod a-w /home/ftpuser/ftp
Verify FTP folder permissions.
sudo ls -la /home/ftpuser/ftp
root@iphone:/home/ftpuser# sudo ls -la /home/ftpuser/ftp total 8 dr-xr-xr-x 2 nobody nogroup 4096 Jun 8 19:01 . drwxr-xr-x 3 ftpuser ftpuser 4096 Jun 8 19:02 .. root@iphone:/home/ftpuser#
Create a directory for file uploads and assign ownership to ftpuser.
sudo mkdir /home/ftpuser/ftp/files sudo chown ftpuser:ftpuser /home/ftpuser/ftp/files
Verify the new folder permission.
sudo ls -la /home/ftpuser/ftp
root@iphone:/home/ftpuser/ftp/files# sudo ls -la /home/ftpuser/ftp total 12 dr-xr-xr-x 3 nobody nogroup 4096 Jun 8 19:08 . drwxr-xr-x 3 ftpuser ftpuser 4096 Jun 8 19:02 .. drwxr-xr-x 2 ftpuser ftpuser 4096 Jun 8 19:08 files root@iphone:/home/ftpuser/ftp/files#
Create and add txt file to the files folder we created in the step above.
echo "Test create txt file" | sudo tee /home/ftpuser/ftp/files/txt01.txt
Configuring VsFTPD
Edit the VsFTPD configuration file vsftpd.conf
cd etc/ sudo nano vsftpd.conf
## # Allow anonymous FTP? (Disabled by default). anonymous_enable=NO # # Uncomment this to allow local users to log in. local_enable=YES ##
Enable uploading to the FTP server by uncomment the write_enable parameter.
## write_enable=YES ##
Prevent the FTP users from accessing files or to run commands outside there directory by uncomment the chroot_local_user=YES parameter.
## chroot_local_user=YES ##
Scroll down to the bottom and add the the port range for passive FTP.
pasv_min_port=40000 pasv_max_port=50000
Previously we created a ftp/file directory and folder for the ftpsuser, now we need to configure VsFTPD to log the ftpuser to home ftp directory we created by adding the line bellow.
user_sub_token=$USER local_root=/home/$USER/ftp
Restart the daemon.
sudo systemctl restart vsftpd
Testing The FTP Access
You can use a ftp client like FileZilla or the command line to confirm that you can access the ftp server and that you can see the txt file you created in the ftpuser ftp directory.
I am using the command line on the FTP server in this example to confirm that i can access the FTP and that i can download the txt01.txt.
root@iphone:/# ftp 127.0.0.1 Connected to 127.0.0.1. 220 (vsFTPd 3.0.3) Name (127.0.0.1:toor): ftpuser 331 Please specify the password. Password: 230 Login successful. Remote system type is UNIX. Using binary mode to transfer files. ftp>
Lets confirm that we can change to the “files” directory.
ls cd files
ftp> ls 200 PORT command successful. Consider using PASV. 150 Here comes the directory listing. drwxr-xr-x 2 1001 1001 4096 Jun 08 19:17 files 226 Directory send OK. ftp> cd files 250 Directory successfully changed. ftp>
List the directory and use the get command to transfer the test file.
ls get txt01.txt
ftp> ls 200 PORT command successful. Consider using PASV. 150 Here comes the directory listing. -rw-r--r-- 1 0 0 21 Jun 08 19:16 txt01.txt 226 Directory send OK. ftp> get txt01.txt local: txt01.txt remote: txt01.txt 200 PORT command successful. Consider using PASV. 150 Opening BINARY mode data connection for txt01.txt (21 bytes). 226 Transfer complete. 21 bytes received in 0.00 secs (259.5926 kB/s) ftp>
Upload the file with a new name to test users write permissions. To upload a file we use the put command.
put txt01.txt txt01-upload.txt
ftp> put txt01.txt txt01-upload.txt local: txt01.txt remote: txt01-upload.txt 200 PORT command successful. Consider using PASV. 150 Ok to send data. 226 Transfer complete. 21 bytes sent in 0.00 secs (1.0541 MB/s) ftp>
Listing the files directory should show two files now.
ls
ftp> ls 200 PORT command successful. Consider using PASV. 150 Here comes the directory listing. -rw------- 1 1001 1001 21 Jun 08 21:00 txt01-upload.txt -rw-r--r-- 1 0 0 21 Jun 08 19:16 txt01.txt 226 Directory send OK. ftp>
(Optional) Secure The FTP Server With TLS
Lets start adding the firewall rule for TLS traffic, add port 990 to the firewall access list.
sudo ufw allow 990/tcp
root@iphone:/# sudo ufw allow 990/tcp Rule added Rule added (v6) root@iphone:/#
Confirm firewall status
sudo ufw status
root@iphone:/# sudo ufw status Status: active To Action From -- ------ ---- 22/tcp ALLOW Anywhere OpenSSH ALLOW Anywhere 21/tcp ALLOW Anywhere 40000:50000/tcp ALLOW Anywhere 990/tcp ALLOW Anywhere 22/tcp (v6) ALLOW Anywhere (v6) OpenSSH (v6) ALLOW Anywhere (v6) 21/tcp (v6) ALLOW Anywhere (v6) 40000:50000/tcp (v6) ALLOW Anywhere (v6) 990/tcp (v6) ALLOW Anywhere (v6) root@iphone:/#
Create a OpenSSL certificate for TLS/SSL encryption, first make a directory where you can save the certificate.
sudo mkdir /etc/ftpcert
Now we will create a new certificate, use the -days flag to make it valid for two years, 730 days. Next set the bit value of the RSA key, i am running with a 2048-bit RSA key.
Type in the -keyout and the -out flag, the flags will set the key values for the private key and the certificate, setting both flags with the same value will create both the private key and the certificate in the same file.
You will be asked to enter details like country, state, etc. You don’t have to fill in the information. Just keep pressing ENTER for defaults.
sudo openssl req -x509 -nodes -days 730 -newkey rsa:2048 -keyout /etc/ftpcert/vsftpd.pem -out /etc/ftpcert/vsftpd.pem
Confirm that the private key and the certificate is the ftpscert directory.
root@iphone:/# cd /etc/ftpcert/ root@iphone:/etc/ftpcert# ls vsftpd.pem root@iphone:/etc/ftpcert#
Next we need to configure vsftpd to allow TLS/SSL traffic and point out the directory of the private key and the certificate , open the vsftpd configuration file with a editor.
cd etc/ sudo nano vsftpd.conf
Scroll down until you find the rsa parameters, Comment them out and replace them with new lines that points out the privet key and the certificate we created.
## # rsa_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem # rsa_private_key_file=/etc/ssl/private/ssl-cert-snakeoil.key ## rsa_cert_file=/etc/ftpcert/vsftpd.pem rsa_private_key_file=/etc/ftpcert/vsftpd.pem
Configure FTP connections to use use SSL/TLS, change the ssl_enable=NO parameter to YES.
## ssl_enable=YES ##
Now add the following lines to deny anonymous connections over SSL and to require SSL for logging and transferring data.
## allow_anon_ssl=NO force_local_data_ssl=YES force_local_logins_ssl=YES ##
Configure the server to use the TLS protocol
## ssl_tlsv1=YES ssl_sslv2=NO ssl_sslv3=NO ##
Last configure SSL reuse parameter to NO due that it can have conflicts with FTP clients, next we need to use high encryption cipher suite, which means that the key lengths is equal to or greater than 128 bits. Paste thee lines below.
## require_ssl_reuse=NO ssl_ciphers=HIGH ##
The configuration should have the below entry’s configured.
# rsa_cert_file=/etc/ftpcert/vsftpd.pem rsa_private_key_file=/etc/ftpcert/vsftpd.pem # # ssl_enable=YES # allow_anon_ssl=NO force_local_data_ssl=YES force_local_logins_ssl=YES ## ssl_tlsv1=YES ssl_sslv2=NO ssl_sslv3=NO # require_ssl_reuse=NO ssl_ciphers=HIGH #
Restart the VsFTPD to load the new configuration.
sudo systemctl restart vsftpd
Confirm FTP TLS Configuration
Download a FTP client like FileZilla, you grab the FileZilla client from the official site https://filezilla-project.org/
Run and install the FTP client, when connecting to the FTP server use “Require explicit FTP over TLS”. If everything is configured correct you should be grated with a pop up windows that displays the server certificate we created.
If you try to connect to the FTP server with just plain FTP protocol, you will get an error and you wont be able to connect to the server.
Status: Connection established, waiting for welcome message... Response: 220 (vsFTPd 3.0.3) Command: USER ftpuser Response: 530 Non-anonymous sessions must use encryption. Error: Could not connect to server
Conclusion
In this quick guide we have installed a FTP server on Ubuntu18.04.02, generated a certificate with OpenSSL and secured the server connectivity with TLS.