ssh create user+key

ssh_key.sh

# ssh to server

# ---

# add new user

sudo adduser user
# sudo cp /etc/sudoers /etc/sudoers.bak
# echo "user ALL=(ALL) ALL" | sudo tee -a /etc/sudoers
# or
# usermod -aG sudo user
# gpasswd -d user sudo
su - user

# ---

# on new user 
# create key and key.pub

mkdir -p $HOME/.ssh
chmod 0700 $HOME/.ssh
touch $HOME/.ssh/authorized_keys
chmod 600 $HOME/.ssh/authorized_keys

# ssh-keygen -t rsa -b 4096 -f ~/.ssh/key
ssh-keygen -t ed25519 -f ~/.ssh/key
cat ~/.ssh/key.pub >> ~/.ssh/authorized_keys

cat ~/.ssh/key # copy

# ---

# switch login by pkey + passwd
echo 'PasswordAuthentication yes' >> /etc/ssh/sshd_config
echo 'AuthenticationMethods "publickey,password"' >> /etc/ssh/sshd_config

# ---

sudo systemctl restart ssh

# --- home pc

nano pkey.pem # paste
chmod 400 ./pkey.pem
ssh -i "pkey.pem" user@ip