Install mc

apt-get update && apt-get upgrade -y && apt-get install -y mc && apt-get install -y git

Create user, setup ssh

sudo adduser fivem
usermod -aG sudo fivem
su fivem
mkdir /home/fivem/.ssh -m 0700

Generate ssh key on the local machine:

ssh-keygen -o -t ed25519 -f id_hh

Copy public key from id_hh.pub file on the local machine

And

Paste it to /home/fivem/.ssh/authorized_keys file on the server

nano /home/fivem/.ssh/authorized_keys

Setup ssh

sudo tee /etc/ssh/sshd_config <<EOF
Port 22022
HostKey /etc/ssh/ssh_host_ed25519_key
PermitRootLogin no
PubkeyAuthentication yes
PasswordAuthentication no
ChallengeResponseAuthentication no
#AllowUsers username1 username2 username3
#AllowUsers fivem

UsePAM no
X11Forwarding yes
PrintMotd no
AcceptEnv LANG LC_*
Subsystem sftp  /usr/lib/openssh/sftp-server
EOF

Restart ssh server

sudo systemctl restart ssh

Setup firewall

sudo ufw allow 22022/tcp
sudo ufw allow 443/tcp
sudo ufw allow 80/tcp
sudo ufw enable
sudo ufw status verbose