Log in locally and remotely

• On a server without a graphical desktop you get a text login prompt: server1 login:.
• On a server with a desktop you log in on the graphical login screen; a terminal window then gives you a shell.
• The text in /etc/issue is shown before the login prompt.

After login, check who you are and where:

$whoami
$tty
/dev/tty3
$hostname

On a server without a desktop, Alt+F1 … Alt+F6 switch between text consoles. As root you can also use chvt N.

#chvt 3

$tty
/dev/pts/0
$who
student  tty2         2026-10-25 08:10 (tty2)
student  pts/0        2026-10-25 09:02 (192.168.122.1)
$w

• tty shows your own terminal.
• who lists who is logged in, on which terminal and from where.
• w shows the same plus what each user is doing now and the load of the system.

#systemctl reboot
#systemctl poweroff
#shutdown -r +5 "Reboot for kernel update in 5 minutes"
#shutdown -c
#shutdown -h now

• systemctl reboot / systemctl poweroff = restart / switch off now. reboot and poweroff are short forms.
• shutdown can wait (+5 = in 5 minutes, 22:00 = at a time) and sends a message to logged-in users. shutdown -c cancels it.
• systemctl halt stops the system but does not switch off the power.

$ssh student@server2
$ssh server2
$ssh -p 2222 student@server2
$ssh root@server2 'df -h /'
$exit

• ssh user@host logs in as that user. Without user@, your own user name is used.
• The first time, SSH shows the fingerprint of the server and asks you to trust it. Answer yes only when you are sure it is the right server. It is then saved in ~/.ssh/known_hosts.
• A command after the host runs on the remote system and SSH ends at once.
• -X (or -Y) lets you start graphical programs from the remote server on your screen.

$scp /etc/hosts student@server2:/tmp/
$scp student@server2:/var/log/messages ./server2-messages
$scp -r ~/project server2:/home/student/
$scp -P 2222 backup.tar.gz server2:/srv/

• -r copies folders.
• -P (capital) sets the port. (In ssh it is a small -p.)
• -p (small) keeps times and permissions.

$sftp student@server2

The l in front means "local". Everything else works on the remote side.

1. Make a key pair on the client (your computer or server1).

   $ssh-keygen -t ed25519

2. Copy the public key to the server.

   $ssh-copy-id student@server2

3. Log in: no password is asked any more (only the passphrase of the key, if you set one).

   $ssh student@server2

$ssh server2 'ls -ld ~/.ssh; ls -l ~/.ssh/authorized_keys'

$ssh-keygen -t ed25519 -C "student@server1"
$eval "$(ssh-agent)"
$ssh-add
$ssh-add -l

• With a passphrase: safer, but you must unlock the key.
• Without a passphrase: needed for automatic jobs (cron, scripts), but protect the key file well and limit what it can do on the server.

$su - root
#exit
$sudo -i
#exit

Chapter 6 explains su and sudo in detail.

1. Install it and start the socket.

   #dnf install -y cockpit
   #systemctl enable --now cockpit.socket

2. Open the firewall (often already open on RHEL).

   #firewall-cmd --add-service=cockpit --permanent
   #firewall-cmd --reload

3. Open https://server1:9090 in a browser and log in with a normal user. Choose "administrative access" to make changes.

• Local logins use virtual consoles (Ctrl+Alt+F1…F6, or chvt); remote shells use pseudo terminals (/dev/pts/N).
• Reboot with systemctl reboot and stop with systemctl poweroff; never just pull the power.
• ssh user@host opens a remote shell; the first connection asks you to trust the host key (saved in ~/.ssh/known_hosts).
• scp and sftp copy files over SSH; rsync copies only what changed and can keep permissions (-a).
• Key-based login: ssh-keygen makes a key pair, ssh-copy-id puts the public key in ~/.ssh/authorized_keys on the server.
• A passphrase protects the private key; ssh-agent and ssh-add keep it unlocked for a session.
• su - switches to another user with a full login environment.
• Cockpit is the web console (port 9090) for many admin tasks.