ftp file access security
Solution 1:
FTP is inherently insecure as it transmits everything en clair.
As you already have ssh then either use scp or sftp both of which leverage the ssh protocol. You can even use clients like filezilla to connect to your sftp server.
If not already enabled, you can add
Subsystem sftp /usr/lib/openssh/sftp-server
to your /etc/ssh/sshd_config file to to so.
You can further lock down the specific user by adding directives to the sshd_config (if that's needed)
Match User alice
# Force the connection to use SFTP and chroot to the required directory.
ForceCommand internal-sftp
ChrootDirectory /home/alice
# Disable tunneling, authentication agent, TCP and X11 forwarding.
PermitTunnel no
AllowAgentForwarding no
AllowTcpForwarding no
X11Forwarding no
That would only let alice connect using sftp and not ssh/scp.