To log in to a remote server without entering a password, we need SSH keys. Let's start generating them:
ssh-keygen -t rsa
When prompted for a passphrase, leave it empty; otherwise, you will have to enter it every time you connect. The save path can be arbitrary.
Before copying the public key to the server, rename it to authorized_keys:
cd ~/.ssh
cp id_rsa.pub authorized_keys
Copy the public key to the remote machine:
cd ~/.ssh scp authorized_keys user@host.servername.com:/root/.ssh/
You can also copy the key using ssh-copy-id, specifying the port with the -p option.
ssh-copy-id '-p 11000 user@host.servername.com'
Now you can log in without entering a password:
ssh user@host.servername.com