How to Setup SFTP Server on AlmaLinux 9

To set up an SFTP server on AlmaLinux 9, follow these steps:

Step 1 : Check if SSH is Running

Run the following command to ensure the SSH service is active:

systemctl status sshd

Step 2 : Configure SSH for SFTP

Edit the SSH configuration file:

nano /etc/ssh/sshd_config

Add or modify the following lines at the end of the file:

Subsystem sftp internal-sftp

Match Group sftp
        ChrootDirectory %h
        X11Forwarding no
        AllowTcpForwarding no
        ForceCommand internal-sftp

Step 3 : Enable Password Authentication (Optional)

If you want to allow password-based login, ensure the following line is set to yes:

PasswordAuthentication yes

Step 4 : Restart SSH Service

Apply the changes by restarting the SSH service:

systemctl restart sshd

Step 5 : Create an SFTP Group

Create a dedicated group for SFTP users:

groupadd sftp

Step 6 : Create an SFTP User

Add a new user and assign them to the SFTP group:

sudo adduser sftpuser

Step 7 : Set a Password for the User

Assign a password to the SFTP user:

passwd sftpuser

Step 8 : Assign User to SFTP Group

Ensure the user is part of the sftpgroup:

sudo usermod -aG sftp sftpuser

Step 9 : Configure Permissions

Set proper permissions to restrict user access:

sudo chown root:root /home/sftpuser
sudo chmod 755 /home/sftpuser
sudo mkdir /home/sftpuser/upload
sudo chown sftpuser:sftpuser /home/sftpuser/upload
sudo chmod 755 /home/sftpuser/upload

Step 10 : Restart SSH Service

Restart the SSH service again to apply the changes:

systemctl restart sshd

Step 11 : Test SFTP Connection

- Open an SFTP Client (e.g., FileZilla)

- Add a New Site

Enter "Host" (Server IP or Domain)

Select "SFTP - SSH File Transfer Protocol"

Set "Port" to 22

Choose "Normal" and enter username & password

- Click "Connect"

- If prompted with an "Unknown Host Key" warning, click "OK"

Congratulations! You have successfully set up an SFTP server on AlmaLinux 9.