1. Check for existing SSH Key

ls -al ~/.ssh/id_*.pub

if there are existing keys, u can either those ans skip the next step.

if u got an output with „No such file or directory or no matches found“ that means that u do not have an SSH Key . U must generate a new one., proceed with the next step

2. Generate a new SSH Key pair

// this generates a 4096 bits SSH Key pair
ssh-keygen -t rsa -b 4096 -C "your_email@domain.com"

// Press Enter to accept the default location and name
# Output: 
# Enter file in which to save the key (/home/yourusername/.ssh/id_rsa):

// Press Enter otherwise u can't startup fully automated processes 
# Output:
# Enter passphrase (empty for no passphrase):

//to be sure that SSH Keey are generated
ls ~/.ssh/id_*

# Output:
# /home/yourusername/.ssh/id_rsa 
# /home/yourusername/.ssh/id_rsa.pub

3. Copy the public Key

//The easy was to copy:
ssh-copy-id remote_username@server_ip_address

//The hard way to copy 
cat ~/.ssh/id_rsa.pub | ssh remote_username@server_ip_address "mkdir -p ~/.ssh && chmod 700 ~/.ssh && cat >> ~/.ssh/authorized_keys && chmod 600 ~/.ssh/authorized_keys"

4. Login in your Server using SSH Keys

ssh remote_username@server_ip_address