Secure SSH on Ubuntu

Change Root Password

passwd

Create a User

adduser admin
su admin
mkdir ~/.ssh
chmod 700 ~/.ssh
touch ~/.ssh/authorized_keys
chmod 600 ~/.ssh/authorized_keys
cat > ~/.ssh/authorized_keys
* Paste the public key here, Then press ctrl-D *
exit

Secure SSH access

listen on non-standard port
do not allow root access
only allow key login

Edit config

vi /etc/ssh/sshd_config

Port 55000
PermitRootLogin no
PasswordAuthentication no

Restart SSHD

service sshd restart

Update Firewall

ufw allow 55000/tcp
ufw delete allow 22/tcp
ufw status verbose