HOWTO: Setup SSH host aliases and paswordless access with RSA key pairs

a) Generate ED25519 public-private key pair

ssh-keygen -t ed25519 -C "<email_address>"    // modern system

OR

ssh-keygen -t rsa -b 4096 -C "email_address"  // legacy system

b) Skip passphrase entering (do not enter passphrase)

c) Copy public SSH key to remote server

scp -v ~/.ssh/<keyname>.pub <username>@<servername>:~/.ssh/authorized_keys

d) If necessary add new public keys by copying public key into new line of ~/.ssh/authorized_keys

e) Configure host aliases in ‘~/.ssh/config’ file

Host *
PreferredAuthentications publickey,keyboard-interactive
ServerAliveInterval 120
ServerAliveCountMax 30

Host hpdc
User <username>
HostName hpdc.eeecs
Port <port_no>
IdentityFile ~/.ssh/<keyname>  // no '.pub' extension required

f) Use ssh and scp as

ssh hpdc OR
scp file.txt hpdc:~

HOWTO: Enable SSH access on macOS

a) Open “System Preferences” -> “Sharing”

b) Tick box next to “Remote login”

https://knowledge.autodesk.com/support/smoke/troubleshooting/caas/sfdcarticles/sfdcarticles/Enabling-remote-SSH-login-on-Mac-OS-X.html

HOWTO: Change default SSH port number on macOS

a) Edit /etc/services file replacing default ssh port numbers with custom number

sudo vim /etc/services

b) Stop SSH daemon

sudo launchctl unload /System/Library/LaunchDaemons/ssh.plist

c) Start SSH daemon

sudo launchctl load -w /System/Library/LaunchDaemons/ssh.plist

http://www.artdecoded.net/blog/how-to-change-the-ssh-port-in-mac-os-x/

HOWTO: Remove entry from ‘known_hosts’ file

ssh-keygen -R *ip_address_or_hostname*

https://serverfault.com/questions/321167/add-correct-host-key-in-known-hosts-multiple-ssh-host-keys-per-hostname