Checking the ssh connection:

Configure the SSH Client

hostname: print the hostname
ssh:
- ssh 192.168.56.105: ssh to remote machine with ip 192.168.56.105 and with the user as current hostname
  - Public key must be accepted, so it can encrypt the ssh connection with it
  - It'll copy the pub_key to the .ssh/known_hosts directory
Add aliases for remote ssh hosts
- aliases are stored in .ssh/config file
- Example: You can access server1 as the root user by just ssh server1
```
Host server1
  Hostname 192.168.103.99
  Port 22
  User root
```

You can generate ssh private key by running ssh-key -t rsa
Authenticate certain ssh host, we copy the public key to the target user of the server
- ssh-copy-id -i id_rsa.pub server1
We can pre-authenticate to the private key by:
- ssh-agent
- ssh-add: add the cached credentials to the ssh-agent. When run without arguments, it adds the files ~/.ssh/*
- On server you can change PermitRootLogin in /etc/ssh/sshd_config to without-password to only allow root logins if they're pre-authenticated

You can copy files securely through machines via SCP
- From host to server1: scp /etc/hosts server1:/tmp
- From server2 to host: scp server2:/tmp/hosts /tmp